WO2021042653A1 - 路径切换方法、通信装置和通信系统 - Google Patents

路径切换方法、通信装置和通信系统 Download PDF

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Publication number
WO2021042653A1
WO2021042653A1 PCT/CN2020/070752 CN2020070752W WO2021042653A1 WO 2021042653 A1 WO2021042653 A1 WO 2021042653A1 CN 2020070752 W CN2020070752 W CN 2020070752W WO 2021042653 A1 WO2021042653 A1 WO 2021042653A1
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transport layer
layer connection
network element
proxy network
connection
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PCT/CN2020/070752
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English (en)
French (fr)
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余芳
李岩
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华为技术有限公司
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Priority to EP20860253.2A priority Critical patent/EP4024955A4/en
Priority to CN202080059709.2A priority patent/CN114270942A/zh
Publication of WO2021042653A1 publication Critical patent/WO2021042653A1/zh
Priority to US17/687,195 priority patent/US20220225211A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W40/00—Communication routing or communication path finding
    • H04W40/34—Modification of an existing route
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W40/00—Communication routing or communication path finding
    • H04W40/34—Modification of an existing route
    • H04W40/36—Modification of an existing route due to handover
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/22—Alternate routing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L47/00—Traffic control in data switching networks
    • H04L47/10—Flow control; Congestion control
    • H04L47/19—Flow control; Congestion control at layers above the network layer
    • H04L47/193—Flow control; Congestion control at layers above the network layer at the transport layer, e.g. TCP related
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/10—Architectures or entities
    • H04L65/1016—IP multimedia subsystem [IMS]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/10—Architectures or entities
    • H04L65/1045—Proxies, e.g. for session initiation protocol [SIP]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/10—Architectures or entities
    • H04L65/1063—Application servers providing network services
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/1066—Session management
    • H04L65/1069—Session establishment or de-establishment
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/80—Responding to QoS
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/0268—Traffic management, e.g. flow control or congestion control using specific QoS parameters for wireless networks, e.g. QoS class identifier [QCI] or guaranteed bit rate [GBR]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/02—Buffering or recovering information during reselection ; Modification of the traffic flow during hand-off
    • H04W36/026—Multicasting of data during hand-off
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/12—Reselecting a serving backbone network switching or routing node
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W40/00—Communication routing or communication path finding
    • H04W40/02—Communication route or path selection, e.g. power-based or shortest path routing
    • H04W40/12—Communication route or path selection, e.g. power-based or shortest path routing based on transmission quality or channel quality
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
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    • H04W40/00—Communication routing or communication path finding
    • H04W40/24—Connectivity information management, e.g. connectivity discovery or connectivity update
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W40/00—Communication routing or communication path finding
    • H04W40/24—Connectivity information management, e.g. connectivity discovery or connectivity update
    • H04W40/28—Connectivity information management, e.g. connectivity discovery or connectivity update for reactive routing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W76/00—Connection management
    • H04W76/10—Connection setup
    • H04W76/12—Setup of transport tunnels
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/16—Multipoint routing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/302—Route determination based on requested QoS
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0011—Control or signalling for completing the hand-off for data sessions of end-to-end connection
    • H04W36/0033—Control or signalling for completing the hand-off for data sessions of end-to-end connection with transfer of context information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0055—Transmission or use of information for re-establishing the radio link
    • H04W36/0069—Transmission or use of information for re-establishing the radio link in case of dual connectivity, e.g. decoupled uplink/downlink
    • H04W36/00695—Transmission or use of information for re-establishing the radio link in case of dual connectivity, e.g. decoupled uplink/downlink using split of the control plane or user plane
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W80/00—Wireless network protocols or protocol adaptations to wireless operation
    • H04W80/06—Transport layer protocols, e.g. TCP [Transport Control Protocol] over wireless

Definitions

  • This application relates to the field of communication, and more specifically, to a path switching method, communication device, and communication system.
  • an air interface handover is triggered, that is, the base station of the terminal device is switched from the original base station to the current base station.
  • the terminal device is still accessing the original user plane network element at this time.
  • the user plane network element closest to the terminal device may have changed at this time, but the terminal device is still
  • the message is transmitted with the original user plane network element. In this case, the transmission path is longer. Accordingly, the transmission delay of the message will increase, which affects the user experience.
  • the present application provides a path switching method, communication device, and communication system.
  • the path switching process since the status interaction situation of the service layer is fully considered, the service delay can be reduced and the user experience can be improved.
  • a path switching method including: if a source transport layer proxy network element determines that path switching is required, the source transport layer proxy network element receives a complete service request sent by a first application server. After the service responds to the message, the data transmission path is switched from the first path to the second path.
  • the first path is a path established between the terminal device and the first application server, the first path includes a first transport layer connection and a second transport layer connection, and the first transport layer connection is The transmission layer connection between the source transport layer proxy network element and the terminal device, the second transmission layer connection is the transmission layer connection between the source transport layer proxy network element and the first application server, and The second path includes a third transmission layer connection and a fourth transmission layer connection, the third transmission layer connection is a transmission layer connection between a target transmission layer proxy network element and the terminal device, and the fourth transmission layer connection It is the transport layer connection between the target transport layer proxy network element and the second application server.
  • the terminal device can establish a transport layer connection with the source transport layer proxy network element and the target transport layer proxy network element.
  • the source transport layer proxy network element can After receiving the complete service response message for the service request sent by the terminal device, the data transmission path is switched from the transmission layer connection between the terminal device and the source transmission layer agent network element to the terminal device and the target transmission layer agent Transport layer connection between network elements. In this way, it is possible to avoid the problem that the same service request needs to be repeatedly initiated after the path switch because the complete service response message for the service request sent by the terminal device is not received.
  • the method provided in this application fully considers the status interaction situation of the service layer, thereby being able to reduce service delay and improve user experience.
  • the first transport layer connection can be a multipath transmission control protocol (MPTCP) connection or a transmission control protocol (multipath transmission control protocol, TCP) connection
  • the second transport layer connection can be a TCP connection.
  • the first transport layer connection may also be a quick UDP Internet Connections (QUIC)
  • the second transport layer connection may be a user datagram protocol (UDP) connection.
  • the third transport layer connection can be an MPTCP connection or a TCP connection
  • the fourth transport layer connection can be a TCP connection.
  • the third transport layer connection may also be a Quick UDP Internet Connections (QUIC)
  • the fourth transport layer connection may be a user datagram protocol (UDP) connection.
  • the first transport layer connection is an MPTCP connection
  • the third transport layer connection is also an MPTCP connection
  • the first transport layer connection is a TCP connection
  • the third transport layer connection is also a TCP connection.
  • the switching the data transmission path from the first path to the second path includes: the source transport layer proxy network element instructs the terminal device
  • the data transmission path is switched from the first transmission layer connection to the third transmission layer connection, and the first transmission layer connection and the third transmission layer connection are a multipath transmission control protocol (multipath transmission control protocol). protocol, MPTCP) connection, the first transport layer connection and the third transport layer connection belong to the same MPTCP session.
  • MPTCP multipath transmission control protocol
  • the terminal device can switch the data transmission path from the first transmission layer connection to the third transmission layer connection according to the instruction of the source transmission layer proxy network element.
  • the method further includes: the source transport layer proxy network element sends the first transport layer connection context to the target transport layer proxy network element, The context is used for the establishment of the third transport layer connection.
  • the source transport layer proxy network element After the establishment of the first transport layer connection is completed, the source transport layer proxy network element sends the first transport layer connection context to the target transport layer proxy network element, so that the target transport layer proxy network element can establish a third transport layer connection.
  • the switching the data transmission path from the first path to the second path includes: the source transport layer proxy network element transmits to the target The layer proxy network element sends the context of the first transport layer connection, where the context includes a first transport layer connection parameter and a transmission state parameter, and the first transport layer connection parameter is used for generating the third transport layer connection,
  • the transmission state parameter is used to indicate the data transmission state of the first transport layer connection.
  • both the first transport layer connection and the third transport layer connection are TCP connections.
  • the source transport layer proxy network element instructs the terminal device to switch the data transmission path from the first transport layer connection to the third
  • the transport layer connection includes: the source transport layer proxy network element adjusts the priority of the first transport layer connection so that the priority of the third transport layer connection is higher than the priority of the first transport layer connection.
  • the source transport layer proxy network element sending the context of the first transport layer connection to the target transport layer proxy network element includes: the source transport layer proxy The network element sends the context to the session management network element and sends the context to the target transport layer proxy network element.
  • the source transport layer proxy network element determining that a path switch needs to be performed includes: the source transport layer proxy network element receives a message sent by the session management network element Path switch indication message.
  • the source transport layer proxy network element determining that a path switch needs to be performed includes: the source transport layer proxy network element receives a third transport layer connection establishment complete message The third transport layer connection establishment complete message is used to indicate that the third transport layer connection establishment is complete.
  • the source transport layer proxy network element and the target transport layer proxy network element are both user plane network elements, or the source transport layer proxy network element Both the target transport layer proxy network elements and the target transport layer proxy network elements are mobile edge computing (mobile edge computing, MEC) platform network elements.
  • MEC mobile edge computing
  • the source transport layer proxy network element and the target transport layer proxy network element are both mobile edge computing MEC platforms.
  • the method further includes: the source transport layer proxy network element receives the session management network element sent The data network access identifier (DNAI) change notification of the data network access identifier (DNAI), the DNAI change notification includes a target DNAI; the source transport layer proxy network element determines the target transport layer proxy network element according to the target DNAI.
  • DNAI data network access identifier
  • DNAI change notification includes a target DNAI
  • the source transport layer proxy network element determines the target transport layer proxy network element according to the target DNAI.
  • the context includes some or more of the following: the internet protocol address (internet protocol, used by the terminal device for the first transport layer connection) IP) address and port number, hash encryption algorithm information used by the first transport layer connection, key (Key) information, data sequence number (DSN) and subflow sequence number (subflow sequence number, SSN) ) Mapping relationship and initial subflow sequence number (ISSN).
  • IP internet protocol address
  • Key hash encryption algorithm information used by the first transport layer connection
  • Key key
  • DSN data sequence number
  • subflow sequence number subflow sequence number
  • SISN initial subflow sequence number
  • the first application server and the second application server provide the same application service.
  • a path switching method including: a target transport layer proxy network element receives a context of a first transport layer connection, and the first transport layer connection is a transmission between a source transport layer proxy network element and a terminal device Layer connection; the target transport layer proxy network element establishes a third transport layer connection with the terminal device according to the context; after completing the establishment of the third transport layer connection, the target transport layer proxy The network element sends a third transport layer connection establishment complete message to the session management network element or the source transport layer proxy network element, where the third transport layer connection establishment complete message is used to indicate that the third transport layer connection establishment is complete.
  • the target transport layer proxy network element can establish the third transport layer connection according to the context of the first transport layer connection. Therefore, when the terminal device needs to perform path switching, the data transmission path can be switched from the first transmission layer connection to the third transmission layer connection.
  • the source transport layer proxy network element and the target transport layer proxy network element are both user plane network elements, or the source transport layer proxy network element Both the target transport layer proxy network element and the target transport layer proxy network element are mobile edge computing MEC platform network elements.
  • a path switching method including: a session management network element obtains a context of a first transport layer connection, the first transport layer connection being a transport layer connection between a source transport layer proxy network element and a terminal device
  • the session management network element sends the first transport layer connection information to the target transport layer proxy network element Context
  • the context is used to establish a third transport layer connection between the target transport layer proxy network element and the terminal device.
  • the session management network element can send the context of the first transport layer connection between the terminal device and the source transport layer proxy network element to the target transport layer proxy network element, so that the target transport layer proxy network element can be based on This context establishes a third transport layer connection with the terminal device. Furthermore, when the terminal device needs to perform path switching, the data transmission path can be switched from the first transmission layer connection to the third transmission layer connection.
  • the method further includes: in a case where it is determined that the establishment of the third transport layer connection is completed, the session management network element sends an agent to the source transport layer The network element sends path switch instruction information, where the path switch instruction information is used to instruct the source transport layer proxy network element to switch the data transmission path from the first transport layer connection to the third transport layer connection.
  • the source transport layer proxy network element can determine that the establishment of the third transport layer connection is completed according to the handover instruction information.
  • the path switching indication information is specifically used to instruct the source transport layer proxy network element to modify the priority of the first transport layer connection, so that the The priority of the third transport layer connection is greater than the priority of the first transport layer connection.
  • the first transport layer connection and the third transport layer connection are multipath transmission control protocol MPTCP connections, and the first transport layer connection and the The third transport layer connection belongs to the same MPTCP session.
  • the source transport layer proxy network element and the target transport layer proxy network element are both user plane network elements.
  • a path switching method which includes: when a terminal device determines that path switching is required, the terminal device receives a complete service response message for the service request, and then starts from the first data transmission path. The path switches to the second path.
  • the first path is a path established between the terminal device and a first application server
  • the first path includes a first transport layer connection and a second transport layer connection
  • the first transport layer connection is a source A transport layer connection between a transport layer proxy network element and the terminal device
  • the second transport layer connection is a transport layer connection between the source transport layer proxy network element and the first application server
  • the first The second path includes a third transmission layer connection and a fourth transmission layer connection.
  • the third transmission layer connection is a transmission layer connection between a target transmission layer proxy network element and the terminal device
  • the fourth transmission layer connection is a connection between the target transmission layer proxy network element and the terminal device.
  • the transport layer connection between the target transport layer proxy network element and the second application server.
  • the terminal device can establish a transport layer connection with the source transport layer proxy network element and the target transport layer proxy network element respectively.
  • the terminal device can set up a connection between the source transport layer proxy network element and the target transport layer proxy network element. After the complete service response message of the service request sent by the terminal device, it switches from the transport layer connection with the source transport layer proxy network element to the transport layer connection with the target transport layer proxy network element. In this way, it is possible to avoid the problem that the same service request needs to be repeatedly initiated after the path switch because the complete service response message for the service request sent by the terminal device is not received.
  • the method provided in this application fully considers the status interaction situation of the service layer, thereby being able to reduce service delay and improve user experience.
  • the service response message is received by the terminal device from the source transport layer proxy network element, and the service response message indicates the first The priority of the three transport layer connection is higher than the priority of the first transport layer connection.
  • the terminal device determining that path switching is required includes: the terminal device receives the third transport layer sent by the target transport layer proxy network element A connection establishment complete message, where the third transport layer connection establishment complete message is used to indicate that the establishment of the third transport layer connection is complete; or, the terminal device receives path switching instruction information sent by the session management network element.
  • the first transport layer connection and the third transport layer connection are multipath transmission control protocol MPTCP connections, and the first transport layer connection and the The third transport layer connection belongs to the same MPTCP session.
  • the source transport layer proxy network element and the target transport layer proxy network element are both user plane network elements, or the source transport layer proxy network element Both the target transport layer proxy network element and the target transport layer proxy network element are mobile edge computing MEC platform network elements.
  • the first application server and the second application server provide the same application service.
  • a path switching method is provided.
  • a first transport layer connection is established between a terminal device and a first application server, and a second transport layer connection is established between the terminal device and the second application server.
  • the method includes: when the terminal device determines that path switching is required, after receiving a complete service response message for the service request sent by the first application server, connecting the data transmission path from the first transport layer Switch to the second transport layer connection, and the service request comes from the terminal device.
  • the terminal device can establish a transport layer connection with the first application server and the second application server respectively.
  • the terminal device can receive the data sent to the terminal device. After the complete service response message of the service request, switch from the first transport layer connection to the second transport layer connection. In this way, it is possible to avoid the problem that the same service request needs to be repeatedly initiated after the path switch because the complete service response message for the service request sent by the terminal device is not received.
  • the method provided in this application fully considers the status interaction situation of the service layer, thereby being able to reduce service delay and improve user experience.
  • the terminal device determining that a path switch needs to be performed includes: the terminal device receives path switch instruction information sent by a session management network element.
  • the first transport layer connection and the second transport layer connection are multipath transmission control protocol MPTCP connections, and the first transport layer connection and the The third transport layer connection belongs to the same MPTCP session.
  • the first application server and the second application server provide the same application service.
  • a path switching method which includes: in the case that a source transport layer proxy network element determines that path switching is required, if the source transport layer proxy network element receives a new service request report sent by a terminal device Text, the source transport layer proxy network element sends the new service request message and the first transport layer connection context to the target transport layer proxy network element, and the first transport layer connection context is used for the target transmission
  • the layer proxy network element establishes a third transport layer connection.
  • the third transport layer connection is a transport layer connection between the target transport layer proxy network element and the terminal device.
  • the first transport layer connection is The transport layer connection between the terminal device and the source transport layer proxy network element.
  • a path switching method including: a target transport layer proxy network element receives a new service request message and a first transport layer connection context sent by a source transport layer proxy network element; the target transport layer proxy The network element sends the new service request message to the second application server through the fourth transport layer connection, where the fourth transport layer connection is between the target transport layer proxy network element and the second application server
  • the target transport layer proxy network element establishes a third transport layer connection with a terminal device according to the context of the first transport layer connection, and the first transport layer connection is the terminal device
  • the transport layer connection with the source transport layer proxy network element; the target transport layer proxy network element receives the message sent by the terminal device through the third transport layer connection, and passes the fourth transport layer The connection is sent to the second application server.
  • the new service request message means that the service request message is not a segmented service request message, or the service request message is a segmented service request message and is the first segment.
  • a complete service request message corresponding to a service request can be divided into multiple segments for transmission, that is, one segment can be transmitted at a time, and the server responds after receiving all the segments; or the server performs a response for each segment.
  • the server needs to respond to the terminal device according to one or more segments that have been received (for example, the server can respond according to the first segment service request after receiving the first segment service request, and instruct the terminal device The segmentation request that can be learned later can continue to occur; after receiving the second service request, the response is replies according to the first segmentation service request and the second segmentation service request).
  • the terminal device After receiving the complete response message sent by the server, the terminal device can send a new service request message.
  • first transport layer connection and the second transport layer connection may be TCP connections.
  • a transmission layer connection is established between the source transport layer proxy network element and the terminal device.
  • the source transport layer proxy network element determines that path switching is required and detects a new service request report sent by the terminal device.
  • the state of the first transport layer connection on the source transport layer proxy network element can be migrated to the target source transport layer proxy network element, so that the transmission path of the message can be switched from the path with the first application server to The path to the second application server.
  • the context of the first transport layer connection includes the first transport layer connection parameter and the first transmission state parameter, and the first transport layer connection parameter is used for all
  • the first transmission state parameter is used to indicate the data transmission state of the first transmission layer connection.
  • the source transport layer proxy network element determines that path switching is required, including: the source transport layer proxy network element receives the path switch sent by the session management network element Indicates the message.
  • the The method further includes: the target transport layer proxy network element receives the IP address information of the second application server sent by the session management network element, and establishes the fourth transport layer connection according to the IP address information.
  • a path switching method including: a target transport layer proxy network element receives a first transport layer connection context and a second transport layer connection context sent by a source transport layer proxy network element, the first transmission
  • the layer connection is the transport layer connection between the source transport layer proxy network element and the terminal device, and the second transport layer connection is the transport layer connection between the source transport layer proxy network element and the first application server;
  • the target transport layer proxy network element generates a third transport layer connection according to the context of the first transport layer connection, and generates a fifth transport layer connection according to the context of the second transport layer connection, and the third transport layer
  • the connection is the transport layer connection between the target transport layer proxy network element and the terminal device, and the fifth transport layer connection is the transport layer between the target transport layer proxy network element and the first application server Connection; if the target transport layer proxy network element receives a new service request message sent by the terminal device through the third transport layer connection, the target transport layer proxy network element transfers the data transmission path from the first The path is switched to the second path, where the first path is the first
  • the new service request message here means that the service request message is not a segmented service request message, or the service request message is a segmented service request message and is the first segment.
  • a complete service request message corresponding to a service request can be divided into multiple segments for transmission, that is, one segment can be transmitted at a time, and the server (for example, the first application server or the second application server) receives all the segments. After that, it responds; or the server responds to each segment. At this time, the server needs to respond to the terminal device according to one or more segments it has received (for example, the server can respond according to the first segment service request after receiving the first segment service request).
  • the first segmented service request reply response indicating that the terminal device can continue to make the later-learned segmentation request; after receiving the second service request, the response will be responded to according to the first segmented service request and the second segmented service request) .
  • the terminal device After receiving the complete response message sent by the server, the terminal device can send a new service request message; or the terminal device can send a new service request message, new service request message, and corresponding response message, new service request message at any time.
  • the subsequent segmented message corresponding to the service request message and the response message corresponding to the segmented message will be transmitted through the second path, and other service request messages and corresponding service response messages will be transmitted through the third path.
  • first transport layer connection, second transport layer connection, third transport layer connection, and fifth transport layer connection may all be TCP connections.
  • a transport layer connection is established between the source transport layer proxy network element and the terminal device, and when the source transport layer proxy network element determines that path switching is required, the transmission on the source transport layer proxy network element
  • the layer connection state is transferred to the target transport layer proxy network element.
  • the transmission path of the service request message is connected from the transport layer between the target transport layer proxy network element and the first application server Switch to the transport layer connection with the target transport layer proxy network element and the second application server.
  • the method before the target transport layer proxy network element switches the data transmission path from the first path to the second path, the method further includes: the target The transport layer proxy network element obtains the IP address information of the second application server from the session management network element, and establishes the fourth transport layer connection according to the IP address information.
  • the context of the first transport layer connection includes the first transport layer connection parameter and the first transmission state parameter, and the first transport layer connection parameter is used for In the generation of the third transport layer connection, the first transmission status parameter is used to indicate the data transmission status of the first transport layer connection;
  • the context of the second transport layer connection includes the second transport layer connection parameter and the second transmission state parameter.
  • the second transport layer connection parameter is used for the generation of the fifth transport layer connection.
  • the status parameter is used to indicate the data transmission status of the second transport layer connection.
  • a path switching method which includes: when a terminal device determines that path switching is required, if the service request message to be sent is a new service request message, the terminal device transmits the data to the path Switch from the first transport layer connection to the second transport layer connection, wherein the first transport layer connection is the transport layer connection between the terminal device and the first application server, and the second transport layer connection is the A transport layer connection between the terminal device and the second application server.
  • the service request message to be sent is a new service request message, it includes: the service request message to be sent is a segmented service request message, and is a complete service request corresponding to the service request message to be sent The first segment of the message; or, the service request message to be sent is not a segmented service request message.
  • the first application server and the second application server can respectively establish a transport layer connection with the terminal device.
  • the terminal device determines that the service request message to be sent is In the case of a new service request message, the terminal device switches from the transport layer connection with the first application server to the transport layer connection with the second application server.
  • the terminal device determining that path switching is needed includes: the terminal device receives path switching instruction information sent by the session management network element; or, the terminal device determines that the establishment of the second transport layer connection is completed.
  • the first transport layer connection and the second transport layer connection are multipath transmission control protocol MPTCP connections, and the first transport layer connection and the third transport layer connection belong to the same MPTCP session.
  • the first application server and the second application server provide the same application service.
  • a path switching method which includes: when a terminal device determines that path switching is required, if the service request message to be sent is a new service request message, the terminal device will receive data from the data
  • the transmission path is switched from the first path to the second path, where the first path is a path established between the terminal device and the first application server, and the first path includes a first transmission layer connection and a second transmission Layer connection, the first transmission layer connection is a transmission layer connection between a source transmission layer proxy network element and the terminal device, and the second transmission layer connection is a transmission layer connection between the source transmission layer proxy network element and the first A transport layer connection between application servers, the second path includes a third transport layer connection and a fourth transport layer connection, and the third transport layer connection is a transmission between the target transport layer proxy network element and the terminal device Layer connection, the fourth transport layer connection is a transport layer connection between the target transport layer proxy network element and the second application server.
  • the first transport layer connection and the second transport layer connection may be MPTCP connections.
  • the service request message to be sent is a new service request message, it includes: the service request message to be sent is a segmented service request message, and is a complete service request corresponding to the service request message to be sent The first segment of the message; or, the service request message to be sent is not a segmented service request message.
  • the source transport layer proxy network element and the target transport layer proxy network element can respectively establish a transport layer connection with the terminal device.
  • the terminal device determines the service to be sent When the request message is a new service request message, the terminal device switches from the transport layer connection with the first application server to the transport layer connection with the second application server.
  • the terminal device determining that path switching is required includes: the terminal device receives the third transport layer connection establishment complete message sent by the target transport layer proxy network element, and the third transport layer connection The establishment completion message is used to indicate that the establishment of the third transport layer connection is completed; or, the terminal device receives path switching instruction information sent by the session management network element.
  • the first transport layer connection and the third transport layer connection are multipath transmission control protocol MPTCP connections, and the first transport layer connection and the third transport layer connection belong to the same MPTCP session.
  • the source transport layer proxy network element and the target transport layer proxy network element are both user plane network elements, or the source transport layer proxy network element and the target transport layer proxy network element are both mobile Edge computing MEC platform network element.
  • the first application server and the second application server provide the same application service.
  • a path switching method which includes: in a case where a source transport layer proxy network element determines that path switching is required, if the source transport layer proxy network element receives a new service request sent by a terminal device Message, the source transport layer proxy network element sends the new service request message and the first transport layer connection context to the target transport layer proxy network element, and the first transport layer connection context is used for the target
  • the transport layer proxy network element establishes a third transport layer connection, where the third transport layer connection is a transport layer connection between the target transport layer proxy network element and the terminal device, wherein the first transport layer connection is The transport layer connection between the terminal device and the source transport layer proxy network element; the target transport layer proxy network element is connected through the fourth transport layer, and sends the new service request message to the second application server,
  • the fourth transport layer connection is a transport layer connection between the target transport layer proxy network element and the second application server; the target transport layer proxy network element is based on the context of the first transport layer connection , Establish the
  • the new service request message means that the service request message is not a segmented service request message, or the service request message is a segmented service request message and is the first segment.
  • a complete service request message corresponding to a service request can be divided into multiple segments for transmission, that is, one segment can be transmitted at a time, and the server responds after receiving all the segments; or the server performs a response for each segment.
  • the server needs to respond to the terminal device according to one or more segments that have been received (for example, the server can respond according to the first segment service request after receiving the first segment service request, and instruct the terminal device The segmentation request that can be learned later can continue to occur; after receiving the second service request, the response is replies according to the first segmentation service request and the second segmentation service request).
  • the terminal device After receiving the complete response message sent by the server, the terminal device can send a new service request message.
  • first transport layer connection and the second transport layer connection may be TCP connections.
  • a transmission layer connection is established between the source transport layer proxy network element and the terminal device.
  • the source transport layer proxy network element determines that path switching is required and detects a new service request report sent by the terminal device.
  • the state of the first transport layer connection on the source transport layer proxy network element can be migrated to the target source transport layer proxy network element, so that the transmission path of the message can be switched from the path with the first application server to The path to the second application server.
  • a path switching method including: a source transport layer proxy network element receives state transition indication information sent by a session management network element; The target transport layer proxy network element sends the context of the first transport layer connection and the context of the second transport layer connection, where the first transport layer connection is the transport layer connection between the source transport layer proxy network element and the terminal device
  • the second transport layer connection is the transport layer connection between the source transport layer proxy network element and the first application server
  • the context of the first transport layer connection is used by the target transport layer proxy network element to generate the first
  • the context of the second transport layer connection is used by the target transport layer proxy network element to generate a fifth transport layer connection
  • the third transport layer connection is the target transport layer proxy network element and the A transport layer connection between terminal devices, where the fifth transport layer connection is a transport layer connection between the target transport layer proxy network element and the first application server;
  • the target transport layer proxy network element generates the third transport layer connection according to the context of the first transport layer connection, and generates the fifth transport layer connection according to the context of the second transport layer connection;
  • the target transport layer proxy network element If the target transport layer proxy network element receives a new service request message sent by the terminal device through the third transport layer connection, the target transport layer proxy network element switches the data transmission path from the first path To a second path, where the first path is a path established between the terminal device and the first application server, and the first path includes the third transport layer connection and the fifth transport layer Connection, the second path includes the third transport layer connection and the fourth transport layer connection, and the fourth transport layer connection is a transport layer connection between the target transport layer proxy network element and the second application server.
  • the new service request message here means that the service request message is not a segmented service request message, or the service request message is a segmented service request message and is the first segment.
  • first transport layer connection, second transport layer connection, third transport layer connection, and fifth transport layer connection may all be TCP connections.
  • a transport layer connection is established between the source transport layer proxy network element and the terminal device, and when the source transport layer proxy network element determines that path switching is required, the transmission on the source transport layer proxy network element
  • the layer connection state is transferred to the target transport layer proxy network element.
  • the transmission path of the service request message is connected from the transport layer between the target transport layer proxy network element and the first application server Switch to the transport layer connection with the target transport layer proxy network element and the second application server.
  • a communication device which includes modules or units used to implement the methods in any one of the first to thirteenth aspects and the first to thirteenth aspects.
  • a communication device including a processor.
  • the processor is coupled with the memory and can be used to execute instructions in the memory to implement the method in any one of the foregoing first aspect to the thirteenth aspect and any one of the first aspect to the thirteenth aspect.
  • the communication device further includes a memory.
  • the communication device further includes a communication interface, and the processor is coupled with the communication interface.
  • a processor including: an input circuit, an output circuit, and a processing circuit.
  • the processing circuit is configured to receive a signal through the input circuit, and transmit a signal through the output circuit, so that the processor executes any one of the first aspect to the thirteenth aspect and the first aspect to the thirteenth aspect The method in the possible implementation mode.
  • the aforementioned processor can be one or more chips
  • the input circuit can be an input pin
  • the output circuit can be an output pin
  • the processing circuit can be a transistor, a gate circuit, a flip-flop, and various logic circuits, etc.
  • the input signal received by the input circuit may be received and input by, for example, but not limited to, a receiver
  • the signal output by the output circuit may be, for example, but not limited to, output to the transmitter and transmitted by the transmitter
  • the circuit can be the same circuit, which is used as an input circuit and an output circuit at different times.
  • the embodiments of the present application do not limit the specific implementation manners of the processor and various circuits.
  • a processing device including a processor and a memory.
  • the processor is used to read instructions stored in the memory, receive signals through a receiver, and transmit signals through a transmitter to execute any one of the first aspect to the thirteenth aspect and the first aspect to the thirteenth aspect.
  • the method in the implementation mode.
  • processors there are one or more processors and one or more memories.
  • the memory may be integrated with the processor, or the memory and the processor may be provided separately.
  • the memory can be a non-transitory (non-transitory) memory, such as a read only memory (ROM), which can be integrated with the processor on the same chip, or can be set in different On the chip, the embodiment of the present application does not limit the type of the memory and the setting mode of the memory and the processor.
  • ROM read only memory
  • sending instruction information may be a process of outputting instruction information from the processor
  • receiving instruction information may be a process of receiving instruction information by the processor.
  • the data output by the processor can be output to the transmitter, and the input data received by the processor can come from the receiver.
  • the transmitter and receiver can be collectively referred to as a transceiver.
  • the processing device in the above seventeenth aspect may be one or more chips.
  • the processor in the processing device can be implemented by hardware or software.
  • the processor may be a logic circuit, integrated circuit, etc.; when implemented by software, the processor may be a general-purpose processor, which is implemented by reading the software code stored in the memory, and the memory may Integrated in the processor, can be located outside the processor, and exist independently.
  • a computer program product includes: a computer program (also called code, or instruction), which when the computer program is executed, causes the computer to execute the first aspect to The thirteenth aspect and the method in any one of the possible implementation manners of the first to the thirteenth aspects.
  • a computer program also called code, or instruction
  • a computer-readable medium stores a computer program (also called code, or instruction) when it runs on a computer, so that the computer executes the above-mentioned first aspect to The thirteenth aspect and the method in any one of the possible implementation manners of the first to thirteenth aspects.
  • a computer program also called code, or instruction
  • a communication system which includes at least two of the aforementioned source transport layer proxy network element, target transport layer proxy network element, first application server, second application server, and session management network element.
  • the communication system may also include the aforementioned terminal device.
  • FIG. 1 is a schematic diagram of the architecture of the 5G system applied to this application.
  • Figure 2 is a schematic diagram of a PSA handover scenario.
  • FIG. 3 is a schematic diagram of the MPTCP protocol architecture.
  • Fig. 4 is a schematic flowchart of a path switching method provided by the present application.
  • Fig. 5 is a schematic flowchart of a specific example of a path switching method provided by the present application.
  • Fig. 6 is a schematic diagram of a data transmission path before and after path switching.
  • Fig. 7 is a schematic diagram of another data transmission path before and after path switching.
  • Fig. 8 is a schematic flowchart of a specific example of a path switching method provided by the present application.
  • FIG. 9 is a schematic flowchart of a specific example of a path switching method provided by the present application.
  • Fig. 10 is a schematic diagram of a data transmission path before and after path switching.
  • FIG. 11 is a schematic diagram of another data transmission path before and after path switching.
  • Fig. 12 is a schematic flowchart of a path switching method provided by the present application.
  • FIG. 13 is a schematic flowchart of a path switching method provided by the present application.
  • FIG. 14 is a schematic flowchart of a path switching method provided by the present application.
  • FIG. 15 is a schematic flowchart of a path switching method provided by the present application.
  • Fig. 16 is a schematic diagram of a data transmission path before and after path switching.
  • FIG. 17 is a schematic diagram of a data transmission path before and after path switching.
  • FIG. 18 is a schematic diagram of a data transmission path before and after path switching.
  • FIG. 19 is a schematic diagram of a data transmission path before and after path switching.
  • FIG. 20 is a schematic diagram of a data transmission path before and after path switching.
  • FIG. 21 is a schematic block diagram of a communication device provided by an embodiment of the present application.
  • FIG. 22 is a schematic structural diagram of a terminal device provided by an embodiment of the present application.
  • FIG. 23 is a schematic block diagram of another communication device provided by an embodiment of the present application.
  • LTE long term evolution
  • UMTS universal mobile telecommunication system
  • WiMAX worldwide interconnection microwave access
  • 5G fifth generation
  • NR new radio
  • FIG. 1 shows a schematic diagram of a 5G system that can be applied to the present application.
  • the system can be divided into two parts: access network and core network.
  • the access network is used to implement functions related to wireless access, and mainly includes a radio access network (radio access network, RAN) device 102.
  • the core network mainly includes the following key logical network elements: user plane function (user plane function) 103, access and mobility management function (access and mobility management function, AMF) 105, session management function (session management function, SMF) 106 , Policy control function (PCF) 107, unified data management function (unified data management) 109.
  • user plane function user plane function
  • AMF access and mobility management function
  • AMF session management function
  • SMF session management function
  • PCF Policy control function
  • unified data management function unified data management
  • the system 100 may further include a user equipment (UE) 101, a data network (DN) 104, and an application function (AF) 108.
  • UE user equipment
  • DN data network
  • AF application function
  • the UE may also be called terminal equipment.
  • the terminal device can communicate with one or more core networks (core networks, CN) via the RAN device.
  • the terminal device can be called an access terminal, terminal, user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, wireless network device, user agent, or user device.
  • the terminal can be a cellular phone, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a handheld with wireless communication function Devices, computing devices or other devices connected to wireless modems, in-vehicle devices, wearable devices or the Internet of Things, terminal devices in vehicle networks, and terminal devices of any form in future networks, etc.
  • SIP session initiation protocol
  • WLL wireless local loop
  • PDA personal digital assistant
  • RAN equipment is a type of equipment that connects terminal equipment to a wireless network, and may specifically be a base station.
  • the base station may include various forms of base stations, such as: macro base stations, micro base stations (also referred to as small stations), relay stations, access points, and so on.
  • the base transceiver station (BTS) in access, CDMA can also be the base station (NodeB, NB) in wideband code division multiple access (WCDMA), or the evolved base station in LTE (Evolved Node B, eNB or eNodeB), or relay station or access point, or in-vehicle equipment, wearable equipment, and the next generation Node B (gNB) in the 5G system or the public land mobile network that will evolve in the future (public land mobile network, PLMN) base stations in the network.
  • the RAN device is collectively referred to as a base station.
  • UDM has functions such as managing the user's contract data and generating user authentication information.
  • AMF is mainly responsible for UE registration management, UE connection management, UE reachability management, UE access authorization and access authentication, UE security functions, UE mobility management, network slice selection , SMF selection and other functions.
  • the AMF serves as the anchor point of the N1/N2 interface signaling connection and provides the N1/N2 interface session management (SM) message routing for the SMF, and maintains and manages the status information of the UE.
  • SM N1/N2 interface session management
  • SMF is mainly responsible for all control plane functions of UE session management, including UPF selection and control, Internet protocol (IP) address allocation and management, session quality of service (QoS) management, from PCF Obtain policy and charging control (PCC) policies, etc.
  • SMF is also used as the termination point of the SM part in the non-access stratum (NAS) message.
  • PCF has functions such as providing policy rules to the control plane functional entities.
  • AF can be an application server, which can belong to an operator or a third party.
  • UPF is mainly responsible for processing user messages, such as forwarding, charging, etc., and can be used as the anchor point of the protocol data unit (PDU) session connection, that is, the PDU session anchor (PSA) ), responsible for data message filtering, data transmission/forwarding, rate control, billing information generation, user plane QoS processing, uplink transmission authentication, transmission level verification, downlink data packet buffering, and downlink data notification triggering.
  • PDU protocol data unit
  • PDU session anchor responsible for data message filtering, data transmission/forwarding, rate control, billing information generation, user plane QoS processing, uplink transmission authentication, transmission level verification, downlink data packet buffering, and downlink data notification triggering.
  • PDU protocol data unit
  • PDA PDU session anchor
  • UPF can also be used as a branch point for multi-homed PDU sessions.
  • DN a network that provides users with data transmission services, such as IP Multi-media service (IMS), the Internet, and so on.
  • DN can include application server (AS).
  • AS is a software framework that provides an environment for running applications to provide applications with services such as security, data, transaction support, load balancing, and large-scale distributed system management.
  • the UE obtains application messages through communication with the AS. It should be noted that the aforementioned AF is the control plane of the AS.
  • a communication system to which the communication method of the embodiment of the present application can be applied may include more or fewer network elements or devices.
  • the device or network element in Figure 1 can be hardware, software that is functionally divided, or a combination of the two.
  • the devices or network elements in Figure 1 can communicate with other devices or network elements.
  • MEC mobile edge computing
  • the role of the MEC platform network element is mainly to realize the collaboration between the application and the network, such as: providing the MEC application-related configuration information to the MEC application server to enable the interaction between the UE and the MEC application, and to provide the UE with the relevant information of the MEC application. Including the availability of MEC applications, etc.
  • the MEC platform network elements can be deployed in the same data center as the anchor UPF and application servers.
  • the MEC platform network element and the UPF can be deployed as independent network elements, or the functions of the MEC platform network element can be deployed on the UPF.
  • the solutions involved in this application are applicable to scenarios where MEC platform network elements are deployed.
  • the MEC platform network element, the MEC platform, the MEC network element and the MEC (such as source MEC (source MEC, S-MEC), target MEC (target MEC, T-MEC), etc.) can be replaced with each other.
  • the UE when the UE moves from the coverage area of the original base station to the coverage area of the current base station, it will trigger the handover of the air interface, that is, handover the base station of the UE from the original base station to the current base station.
  • the UE still accesses the original user plane network element at this time.
  • the user plane network element closest to the UE may have changed at this time, but the UE is still the same as the original user plane network element.
  • the plane network element transmits the message. In this case, the transmission path is longer, and accordingly, the transmission delay of the message will increase.
  • FIG. 2 shows a schematic diagram of a PSA handover scenario.
  • AS1 and AS2 can provide the same application services.
  • air interface handover is triggered first, user plane data is transmitted through path 1 before the handover, and user plane data is transmitted through path 2 after the handover.
  • the UE accesses the user plane anchor PSA1 through the base station 2, and the user plane transmission path is circuitous and the path delay increases.
  • PSA switching can be achieved through two PDU session modes: (1) service and session continuity mode (service and session continuity mode, SSC mode) 3; (2) uplink class ofoer (UL CL).
  • service and session continuity mode service and session continuity mode 3
  • UL CL uplink class ofoer
  • SSC mode 3 means that when SMF decides that it needs to switch the user plane path, if the UE moves and the user plane path of the original PDU session is not the optimal path, SMF will request the UE to re-establish a new PDU session to the same DN. SMF is The re-established PDU session selects a new PSA, and requests the UE to release the original PDU session when the timer expires or after the service flow has been transferred to the new PDU session.
  • UL CL means that SMF can add a new PSA UPF to the original PDU session and insert a UL CL into the data transmission path of the original PDU session.
  • the "UL CL" function is provided by UPF, and its purpose is to forward data packets that meet service filtering rules to a designated path.
  • UPF with "UL CL” function When a UPF with "UL CL” function is inserted into a PDU session data channel, this PDU session can provide multiple different paths to the same DN through multiple PSAs.
  • the function of "UL CL" is to transmit uplink data to different PDU session anchor points, and combine downlink data to transmit to the UE.
  • a common scenario is that the UPF with UL CL function and the newly-added anchor UPF are co-located, that is, the newly-added PSA UPF also has the UL CL function.
  • this application provides multiple path switching methods.
  • the source transport layer proxy network element for example, PSA UPF or MEC platform network element, etc.
  • Hypertext transfer protocol hyperText transfer protocol, HTTP
  • the client obtains application data from the server through an HTTP request (HTTP request)/HTTP response (HTTP response) message.
  • HTTP request HTTP request
  • HTTP response HTTP response
  • HTTP is a stateless application layer protocol, that is, the content of the current HTTP request has nothing to do with the HTTP request sent by the client before.
  • TCP Transmission control protocol
  • TCP is a connection-oriented, reliable, byte stream-based transport layer communication protocol.
  • TCP gives each packet a sequence number, and the sequence number also ensures that the packets sent to the receiving end are received in order.
  • the receiving end sends back a corresponding acknowledgement (ACK) for the successfully received bytes. If the sending end does not receive the confirmation within a reasonable round-trip time (RTT), then the corresponding data ( (Assumed to be lost) will be retransmitted.
  • RTT round-trip time
  • the client and server establish a TCP connection based on the TCP three-way handshake process:
  • the client sends a TCP synchronization sequence numbers (synchronize sequence numbers, SYN) message to the server and waits for the server to confirm;
  • TCP synchronization sequence numbers synchronize sequence numbers, SYN
  • the server receives the TCP SYN message and replies with a SYN+ACK message
  • the client receives the SYN+ACK message and replies with another ACK message to confirm that it has received the SYN+ACK message.
  • Multipath TCP Multipath TCP, MPTCP
  • MPTCP is a multipath TCP protocol used for multipath transmission. Its core idea is to add a Multipath TCP layer that supports multipath transmission between the application layer and the transport layer to achieve multipath transmission.
  • the Multipath TCP layer of the client can divide the data transmitted by the application layer into multiple TCP sub-streams. Different TCP sub-streams are sent to the server through different network interfaces, and the server will Different TCP sub-streams are aggregated at the MPTCP layer and then delivered to the application layer, thereby realizing multi-path transmission between the client and the server.
  • the MPTCP connection is established between the client and the server based on the MPTCP three-way handshake process:
  • the client sends a TCP SYN message to the server, and an MP_CAPABLE option is included in the MPTCP option field, which includes the client's session key (Key);
  • the server If the server supports MPTCP, it will return a SYN+ACK message, and also include an MP_CAPABLE option in the MPTCP option field, which carries the server-side Key.
  • the client returns an ACK message, and an MP_CAPABLE option is included in the MPTCP option field, which carries the Key of the client and the Key of the server.
  • the session secret key is used by the client and the server to generate a token for identifying the MPTCP session between the client and the server.
  • the session secret key is also used by the client and server to generate a 32-bit hash shared secret key, that is, a hash-based message authentication code (HMAC), so as to establish a new MPTCP session.
  • HMAC hash-based message authentication code
  • An MPTCP session can have two (or more than two) MPTCP connections.
  • the process of creating a new MTPCP connection is similar to the three-way handshake process. The difference is that the message does not carry the MP_CAPABLE option, but the MP_JOIN option.
  • MP_JOIN can contain the original session (connection) token value and the hash sharing of the opposite end. The key, the hash shared key of the opposite end is used for authentication, and the token value of the original session is used to instruct the newly generated MPTCP connection to join the original session.
  • MP_JOIN can also contain a random number to prevent replay attacks.
  • MP_JOIN can also contain the address of the sender, so that even if the address value of the sender is subjected to Network Address Translation (NAT), the peer can still obtain the sender's address.
  • NAT Network Address Translation
  • Fig. 4 is a schematic flowchart of a path switching method provided by the present application. As shown in FIG. 4, the method may include S410 to S440, and each step is described below.
  • S410 Establish a first path between the UE and the first application server.
  • a first transport layer connection is established between the UE and the source transport layer proxy network element
  • a second transport layer connection is established between the source transport layer proxy network element and the first application server.
  • the first transport layer connection and the second transport layer connection constitute a first path.
  • the user plane data may be transmitted between the UE and the first application server through the first path, or in other words, the data transmission may be performed between the UE and the first application server through the first path.
  • the first transport layer connection may be an MPTCP connection or a TCP connection
  • the second transport layer connection may be a TCP connection.
  • first transport layer connection may also be a quick UDP Internet Connections (QUIC)
  • second transport layer connection may be a user datagram protocol (UDP) connection.
  • QUIC quick UDP Internet Connections
  • UDP user datagram protocol
  • the target transport layer proxy network element obtains the context of the first transport layer connection.
  • the context of the first transport layer connection may include an IP address used by the UE for the first transport layer connection.
  • the first transport layer connection may also include the port number of the UE.
  • IP address or IP address information mentioned in this application can be an Internet Protocol version 4 (IPv4) address or an Internet Protocol version 6 (Internet Protocol version 6, IPv6) prefix.
  • the context of the first transport layer connection may also include one or more of the following: Key information and hash of both ends of the first transport layer connection (ie, the UE and the source transport layer proxy network element) Encryption algorithm information (if HMAC-SHA256 encryption algorithm is used), data sequence number (data sequence number, DSN) and subflow sequence number (subflow sequence number, SSN) mapping relationship, initial subflow sequence number (initial subflow sequence number) , ISSN).
  • HMAC-SHA256 data sequence number
  • DSN data sequence number
  • subflow sequence number subflow sequence number, SSN
  • ISSN initial subflow sequence number
  • the source transport layer proxy network element may send the context of the first transport layer connection to the session management network element, and the session management network element is in After detecting that the UE is moving and needs to switch the PSA, the context of the first transport layer connection can be sent to the target transport layer proxy network element.
  • both the source transport layer proxy network element and the target transport layer proxy network element may be user plane network elements, specifically anchor user plane network elements, that is, PSA.
  • the source transport layer proxy network element may be referred to as a source PSA (source PSA, S-PAS)
  • the target transport layer proxy network element may be referred to as a target PSA (target PSA, T-PSA).
  • the source transport layer proxy network element can directly send the context of the first transport layer connection Proxy network element to the target transport layer.
  • the source transport layer proxy network element or the UE may send a first transport layer connection establishment complete message to the session management network element, indicating that the first transport layer connection establishment is complete .
  • the session management network element detects that the UE needs to switch PSA and receives the first transport layer connection establishment message, the session management network element can send a data network access identifier (DNAI) to the source transport layer proxy network element )
  • a change notification, the DNAI change notification may include the target DNAI.
  • the source transport layer proxy network element can determine the target transport layer proxy network element according to the target DNAI, and then can send the context of the first transport layer connection to the target transport layer proxy network element.
  • both the source transport layer proxy network element and the target transport layer proxy network element may be MEC platform network elements. And, in this case, the MEC platform network elements and user plane network elements are deployed separately.
  • the MEC platform network element corresponding to the source transport layer proxy network element may be referred to as the source MEC (source MEC, S-MEC), and the MEC platform network element corresponding to the target transport layer proxy network element may be referred to as the target MEC (target MEC). , T-MEC).
  • the session management network element may be an SMF, or may be a network element with SMF function.
  • SMF Session Management Function
  • the target transport layer proxy network element establishes a second path between the UE and the second application server.
  • the target transport layer proxy network element establishes a third transport layer connection with the UE, and establishes a fourth transport layer connection with the second application server.
  • the third transport layer connection can be established according to the context of the first transport layer connection.
  • the third transport layer connection and the fourth transport layer connection constitute a second path. It can be understood that the user plane data can be transmitted between the UE and the second application server through the second path.
  • the third transport layer connection is also an MPTCP connection, and the first transport layer connection and the third transport layer connection belong to the same MPTCP session; if the first transport layer connection is a TCP Connection, the third transport layer connection is also a TCP connection. If the second transport layer connection is a TCP connection, the fourth transport layer connection may be a TCP connection, but this application does not limit this. Regarding how to establish an MPTCP connection and establish a TCP connection, please refer to the relevant description above or below for details.
  • the first transport layer connection is QUIC
  • the third transport layer connection is also QUIC
  • the second transport layer connection is a UDP connection
  • the fourth transport layer connection is also a UDP connection.
  • the second application server and the first application server may provide the same application service.
  • the second application server and the first application server may be the same server or different servers, which is not limited in this application. In addition, both can belong to the same DN.
  • S440 If the source transport layer proxy network element determines that path switching is required, after receiving the complete service response message for the service request (or called the service request message or the service request message) sent by the first application server, The data transmission path is switched from the first path to the second path. Among them, the service request is sent by the UE.
  • the source transport layer proxy server receives the path switching instruction information sent by the session management network element, or receives the third transport layer connection establishment complete message, if it receives the complete service request sent by the first application server
  • the service response message can switch the data transmission path from the first path to the second path.
  • the source transport layer proxy network element can determine whether it is received by parsing the HTTP response message and the HTTP response message A complete HTTP response message for the HTTP request sent by the first application server. For example, the source transport layer proxy network element can determine whether the HTTP response message is a segment response response message according to the message status code in the HTTP response message. If the HTTP status code carried in the HTTP response message is 200, it means that the HTTP response message has not been processed.
  • the source transport layer proxy network element when the source transport layer proxy network element receives the HTTP response message, it can determine that the complete response message of the corresponding HTTP request message has been received; if the HTTP status code carried in the HTTP response message is 206, it means the first The application server sends service messages to the UE in a segmented response.
  • the source transport layer proxy network element needs to determine whether the received HTTP response message is based on the Range field carried in the HTTP request message and the Content-Range field in the HTTP response message It is not the last response message corresponding to the HTTP request message.
  • the Range field carried in the HTTP request message is the range used by the UE to notify the first application server of the requested content
  • the Content-Range field in the HTTP response message is used by the first application server to notify the range and actual length of the response.
  • the source transport layer proxy network element switching the data transmission path from the first path to the second path may specifically include: the source transport layer proxy network element sends first indication information to the UE, and the first indication information is used for the UE. Switch the data transmission path from the first transport layer connection to the third transport layer connection.
  • the service response message carries the first indication information so that the UE After receiving the response message, the data transmission path is sent from the first transmission layer connection to the third transmission layer connection according to the first indication information.
  • the source transport layer proxy network element can modify the HTTP response message for the HTTP request message or the TCP layer MPTCP of the last HTTP response message.
  • the source transport layer proxy network element receives the complete service response message for the service request within a preset period of time after receiving the handover request message or the third transport layer connection establishment completion message, or in Before receiving the handover request message or the third transport layer connection establishment completion message, if a complete service response message for the service request is received, it can be considered that a complete service response message for the service request has been received.
  • a complete service response message for a service request refers to a complete service response message for the most recent service request sent by the UE.
  • the UE can establish a transport layer connection with the source transport layer proxy network element and the target transport layer proxy network element.
  • the source transport layer proxy network element can be After receiving the complete service response message for the service request sent by the UE, path switching is performed. In this way, it is possible to avoid the problem that the same service request needs to be repeatedly initiated after the path switch because the complete service response message for the service request sent by the UE is not received.
  • the method provided in this application fully considers the status interaction situation of the service layer, thereby being able to reduce service delay and improve user experience.
  • the source transport layer proxy network element and the target transport layer proxy network element can be PSA or MEC.
  • PSA or MEC can integrate transport layer proxy functions, such as TCP and MPTCP proxy functions. The following describes the specific process of the method shown in FIG. 4 for these two situations respectively.
  • the transport layer proxy network element is a PSA.
  • the session management network element is the SMF
  • the source transport layer proxy network element is the source PSA (Source PSA, S-PSA)
  • the target transport layer proxy network element is the target PSA (target PSA, T-PSA)
  • the first application server is a source application server (source AS, S-AS)
  • the second application server is a target AS (target AS, T-AS) as an example for description.
  • Fig. 5 is a schematic flowchart of a path switching method.
  • the first transport layer connection and the third transport layer connection are MPTCP connections
  • the second transport layer connection and the fourth transport layer connection are TCP connections.
  • the method may include S501 to S510, and each step is described below.
  • S501 When the UE determines that the application needs to initiate a service, it associates a PDU session for the service.
  • the UE associates the PDU session for the service. Otherwise, the UE establishes a PDU session for the service by interacting with the core network, and associates the service with the session.
  • Transport layer messages including messages for establishing a transport layer connection.
  • TCP messages, TCP SYN, SYN+ACK, and ACK messages sent during the TCP three-way handshake must pass
  • the corresponding PDU session is sent from the UE to the PSA via the base station, and then sent from the PSA to the AS in the DN.
  • the service message of the UE is transmitted through the TCP connection, that is, after the service message is encapsulated by the UE into a TCP message based on the parameters of the TCP connection, the PDU session corresponding to the TCP connection is sent from the UE to the AS via the base station and PSA. That is, the transport layer connection between each UE and the server needs to be associated with a PDU session, and the transport layer connection between the UE and the S-PSA or T-PSA involved in this application also needs to be associated with a PDU session.
  • the SMF may instruct the S-PSA to activate the TCP proxy function for a specific service data flow (SDF).
  • SDF service data flow
  • the UE, the transport layer proxy network element, or the SMF in this application performs path switching on the message, all of which are performed for a specific one or more service data streams.
  • S502 Establish a first path between the UE and the S-AS.
  • an MPTCP connection is established between the UE and the S-PSA, and a TCP connection is established between the S-PSA and the S-AS.
  • the IP address used by the UE to establish the first path may be allocated to the UE after the S-PSA activates the TCP proxy function during the establishment of the PDU session. Specifically:
  • the S-PSA receives the instructions sent by the SMF, activates the TCP proxy function for a specific service flow, and assigns the UE the IP address used to establish the transport layer connection of the first path, and the N4 session establishment response message or the N4 session modification request message will
  • the IP address is sent to the SMF, and the SMF is sent to the UE through NAS signaling.
  • the UE subsequently uses the IP address to initiate the establishment of the first transport layer connection.
  • the UE may also use the IP address of the PDU session to initiate the establishment of the first transport layer connection.
  • S502 can be implemented in the following ways:
  • the MPTCP connection is established between the S-PSA and the UE based on the MPTCP three-way handshake process, that is, the first transport layer connection between the S-PSA and the UE. details as follows:
  • the SYN message carries a multipath capability MP_CAPABLE option (option), where MP_CAPABLE is used to identify that the local device (ie, UE) supports MPTCP and performs key exchange between the two parties, and j represents a sequence number.
  • the S-PSA receives the ACK message from the UE, completes the three-way handshake with the UE, and establishes the first transport layer connection between the UE and the S-PSA.
  • the TCP connection is established between S-PSA and S-AS based on the TCP three-way handshake process, that is, the second transport layer connection between S-PSA and S-AS. details as follows:
  • the execution steps of the above steps can be: 502-b ⁇ 502-c and 502-d ⁇ 502-f are executed in parallel, that is, while 502-b and 502-c are executed in sequence Execute 502-d, 502-e, 502-f in order; it can also be executed in the order of 502-a, 502-d, 502-e, 502-b, 502-c, 502-f, that is, S-PSA
  • S503 The S-PSA sends the context of the first transport layer connection to the SMF.
  • the S-PSA sends the context of the first transport layer connection to the SMF.
  • the S-PSA may send the context of the first transport layer connection to the SMF through the N4 session modification request message.
  • the context is the context of the MPTCP connection between the UE and the S-PSA, for example, it may include one or more of the following: the IP address and port number used by the UE for the first transport layer connection, the UE at both ends of the MPTCP connection And S-PSA Key information, hash encryption algorithm information (such as HMAC-SHA256 encryption algorithm), the mapping relationship between DSN and SSN, ISSN and other information.
  • S504 The SMF sends the context of the first transport layer connection to the T-PSA.
  • the SMF detects that the UE is moving and needs to switch the PSA, it selects a T-PSA for the UE, and sends the context of the first transport layer connection to the selected T-PSA.
  • the SMF may send the context to the T-PSA through an N4 session modification request message. While sending the context, the SMF may also instruct the T-PSA to activate the TCP proxy function for a specific SDF.
  • the SMF may select the target T-PSA for the UE according to the location of the UE.
  • This application can be applied to two modes, namely UL CL mode and SSC mode 3.
  • SMF selects T-PSA and inserts T-PSA as UL CL; for SSC mode 3, SMF triggers the UE to establish a new PDU session with T-PSA as the user plane anchor point.
  • the S-PSA may directly send the context of the first transport layer connection to the T-PSA.
  • the context can be transmitted by establishing a user plane tunnel between S-PSA and T-PSA.
  • the SMF also sends the T-AS IP address information to the T-PSA.
  • the IP address information is used by the T-PSA to establish a transport layer connection with the T-AS. It can be an IPv4 address, for example,
  • the SMF may send the IP address information to the T-PSA through the N4 session establishment request message or the N4 session modification request message.
  • the T-PSA establishes a second path between the UE and the T-AS.
  • the T-PSA establishes an MPTCP connection with the UE according to the context of the first transport layer connection, that is, the third transport layer connection, so that the third transport layer connection and the first transport layer connection belong to the same MPTCP session, and,
  • the T-PSA establishes a TCP connection with the T-SA, that is, the fourth transport layer connection.
  • the MPTCP connection is established between the T-PSA and the UE based on the MPTCP three-way handshake process, that is, the third transport layer connection between the T-PSA and the UE. details as follows:
  • the SYN message carries the MP_JOIN option, and the MP_JOIN option can carry the T-PSA in the context obtained in step 504
  • the token value of the UE, the IP address of the T-PSA, the local random number of the T-PSA, and p represents the serial number;
  • the SYN+ACK packet carries the MP_JOIN option.
  • the MP_JOIN option carries the HMAC of the UE, the local random number of the UE, the IP address of the UE, and q represents the serial number;
  • the UE receives the ACK message sent by the T-PSA, completes the three-way handshake with the T-PSA, and establishes the third transport layer connection between the UE and the T-PSA.
  • a TCP connection is established between T-PSA and T-AS based on the TCP three-way handshake process, that is, the fourth transport layer connection between T-PSA and T-AS. details as follows:
  • Steps 505-a to 505-c and 505-d to 505-f in the above steps are executed independently, that is, 505-a, 505-b, and 505-c are executed in sequence while 505-d is executed in sequence.
  • 505-e, 505-f it can also execute 505-a, 505-b, 505-c in sequence first, and then execute 505-d, 505-e, 505-f in sequence; or execute 505 in sequence first -d, 505-e, 505-f, and then execute 505-a, 505-b, 505-c in order, this application is not limited.
  • the IP address used by the UE for the second path or the third transport layer connection of the second path may be allocated to the UE by the T-PSA.
  • T-PSA allocates the IP address for the transport layer connection of the second path to the UE
  • T-PSA sends the IP address to SMF
  • SMF sends NAS signaling Sent to UE.
  • the T-PSA may send the IP address to the SMF via the N4 session establishment response message corresponding to the N4 session establishment request message in step S504, or send the IP address to the SMF via the N4 session modification request message.
  • the destination IP address used by T-PSA in 5-505a is the IP address allocated by the UE.
  • the IP address used by the UE for the second path or the third transport layer connection of the second path may also be the IP address of the PDU session.
  • the T-PSA After the establishment of the third transport layer connection is completed, the T-PSA sends a third transport layer connection establishment complete message to the SMF.
  • S507 The SMF sends path switching instruction information to the S-PSA.
  • the SMF sends path switching instruction information to the S-PSA after learning that the third transport layer connection is established to instruct the S-PSA to perform path switching.
  • the S-PSA After receiving the path switching indication information, the S-PSA judges whether it has received a complete service response message sent by the S-AS for the service request sent by the UE.
  • the S-PSA may start to detect the service request message and the service response message after receiving the path switching instruction information sent by the SMF in S507.
  • the S-PSA may start to detect the service request message and the service response message after sending the context of the first transport layer connection to the SMF in S503.
  • the S-PSA may start to detect the service request message and the service response message after receiving the second indication information sent by the SMF, where the second indication information is used to instruct the S-PSA to start detecting the service request message and the service Reply message.
  • the SMF sends the second indication information to the S-PSA
  • it can be when the third transport layer connection establishment complete message sent by the T-PSA is received in S506, or it can be when the SMF detects that the UE is moving and needs to switch the PSA.
  • it may also be that after the SMF sends the context of the first transport layer connection to the T-PSA through step S504, this application does not specifically limit it.
  • the S-PSA can determine whether the S-AS has been received by parsing the HTTP response message and the HTTP response message The sent complete HTTP response message sent by the UE. For example, S-PSA can determine whether the HTTP response message is a segmented response response message based on the message status code in the HTTP response message. If the HTTP status code carried in the HTTP response message is 200, it means that the HTTP response message is not segmented.
  • S-PSA When S-PSA receives the HTTP response message, it can determine that it has received the complete response message of the corresponding HTTP request message; if the HTTP status code carried in the HTTP response message is 206, it means that S-AS responded by segment To send service messages to the UE in a way, S-PSA needs to determine whether the received HTTP response message is the last segment corresponding to the HTTP request message based on the Range field carried in the HTTP request message and the Content-Range field in the HTTP response message Response message.
  • the Range field carried in the HTTP request message is the range used by the UE to inform the S-AS of the requested content
  • the Content-Range field in the HTTP response message is used by the S-AS to inform the range and actual length of the response.
  • the S-PSA sends first indication information to the UE, where the first indication information is used by the UE to switch the data transmission path from the first transmission layer connection to the third transmission layer connection.
  • the S-PSA determines that it has received the complete service response message sent by the S-AS for the service request sent by the UE, it carries the first indication information in the service response message so that the UE can receive After the response message, the data transmission path is switched from the first transmission layer connection to the third transmission layer connection according to the first instruction information.
  • S-PSA can modify the HTTP response message for the HTTP request message or the MPTCP option of the TCP layer of the last HTTP response message, specifically as follows: In the process of encapsulating the HTTP response message, the S-PSA sets the flag B of the MP_PRIO option in the TCP header to 1, that is, modifies the priority of the first transport layer connection to make it an alternative path.
  • S510 The UE switches the data transmission path from the first transmission layer connection to the third transmission layer connection according to the first indication information.
  • the UE determines to switch the data transmission path from the first transport layer connection to the third transport layer connection according to the value of flag B in the MP_PRIO option of the MPTCP option in the service response message .
  • S-PSA and T-PSA can respectively establish an MPTCP connection with the UE.
  • the S-PSA detects the complete service for the service request sent by the UE. After responding to the message, the UE switches the data transmission path from the MPTCP connection with the S-PSA to the MPTCP connection with the T-PSA.
  • the method shown in FIG. 5 can be applied to two modes, namely, the SSC mode 3 and the UL CL mode mentioned in the description of S504 above.
  • SSC mode 3 the data transmission path before and after path switching is shown in Figure 6.
  • UL CL mode the data transmission path before and after path switching is shown in Figure 7.
  • Fig. 8 is a schematic flowchart of a path switching method.
  • the first transport layer connection, the second transport layer connection, the third transport layer connection, and the fourth transport layer connection are all TCP connections.
  • the method may include S801 to S806, and each step will be described below.
  • S801 When the UE determines that the application needs to initiate a service, it associates a PDU session for the service.
  • This step can refer to S501, which will not be repeated here.
  • S802 Establish a first path between the UE and the S-AS.
  • the first transport layer connection is established between the UE and the S-PSA
  • the second transport layer connection is established between the S-PSA and the S-AS
  • both the first transport layer connection and the second transport layer connection are TCP connections.
  • S802 can be implemented in the following ways:
  • a TCP connection is established between the S-PSA and the UE based on the TCP three-way handshake process, that is, the first transport layer connection between the S-PSA and the UE. details as follows:
  • the S-PSA receives the ACK message from the UE, completes the three-way handshake with the UE, and establishes the first transport layer connection between the UE and the S-PSA.
  • the TCP connection is established between S-PSA and S-AS based on the TCP three-way handshake process, that is, the second transport layer connection between S-PSA and S-AS. details as follows:
  • the SMF sends routing information to the T-PSA, and the routing information instructs the T-PSA to establish a TCP connection with the T-AS, that is, the fourth transport layer connection.
  • the SMF detects that the UE is moving and needs to switch the PSA, it selects the T-PSA for the UE and sends the routing information of the N6 interface to the T-PSA. According to the routing information, the T-PSA establishes a fourth transport layer connection with the T-AS.
  • the routing information further includes: IP address information of the T-AS, which is used for the T-PSA to establish a transport layer connection with the T-AS.
  • the SMF can be established through an N4 session
  • the request message or the N4 session modification request message sends the routing information including the IP address information to the T-PSA.
  • S804 Establish a fourth transport layer connection between the T-PSA and the T-AS.
  • the fourth transport layer connection is a TCP connection.
  • the TCP connection is established between T-PSA and T-AS based on the TCP three-way handshake process, and the T-PSA initiates the TCP three-way handshake process.
  • S805 The SMF sends path switching instruction information to the S-PSA.
  • the SMF may select the target T-PSA for the UE and insert the T-PSA as the UL CL when it detects that the UE is moving and needs to switch the PSA. After that, SMF sends path switching instruction information to S-PSA.
  • the SMF may also send path switching indication information after determining that the fourth transport layer connection is established.
  • the SMF may send the path switching instruction information to the S-PSA through the N4 session modification request message.
  • the SMF after inserting the T-PSA as the UL CL, the SMF also instructs the T-PSA to establish a fourth transport layer connection with the T-AS, that is, a TCP connection.
  • the SMF may send to the T-PSA the instruction information instructing the T-PSA to establish the fourth transport layer connection with the T-AS through the N4 session modification request message.
  • the S-PSA After receiving the path switching instruction information, the S-PSA judges whether it has received a complete service response message sent by the S-AS for the service request sent by the UE.
  • the S-PSA can start to detect the service request message and the service response message after receiving the path switching instruction message sent by the SMF in S804; for another example, the S-PSA can start detecting the second instruction message sent by the SMF The service request message and the service response message are detected.
  • the time when the SMF sends the second indication information to the S-PSA may be when the SMF detects that the UE is moving and needs to switch the PSA, which is not specifically limited in this application.
  • the way S-PSA judges whether it has received the complete service response message sent by the S-AS for the service request sent by the UE is the same as in S508 S-PSA judges whether it has received the S-AS sent for the UE.
  • the way of the complete service response message of the service request is the same, which will not be repeated here.
  • the S-PSA sends the context of the first transport layer connection to the T-PSA.
  • the context includes a first transport layer connection parameter and a transmission state parameter.
  • the first transport layer connection parameter is used for the generation of the third transport layer connection
  • the transmission state parameter is used to indicate the data transmission of the first transport layer connection. status.
  • the first transport layer connection parameters include: the IP address and port number used by the UE for the first transport layer connection, and optionally, the IP address and port number of the S-AS; or, optionally, the S-AS The IP address and port number used by the PSA in the first transport layer connection.
  • the transmission state parameters of the first transport layer connection include at least: the TCP sequence number of the uplink data sent on the first transport layer connection, the TCP sequence number of the downlink data sent, and the sequence number of the TCP ACK sent in the uplink and the downlink.
  • the third transport layer connection can be generated, and the third transport layer connection has the same transport layer connection parameters and transmission state parameters as the first transport layer connection. In other words, if you do not perceive the generation of the third transport layer connection, you still think that data is being transmitted through the first transport layer.
  • the T-PSA sends the data from the UE to the T-AS through the fourth transport layer connection, that is, the transmission path is switched from the first path to the second path.
  • the context of the first transport layer connection can be carried by the S-PSA in the HTTP response message and sent to the T-PSA, or the S-PSA can determine that it has received the service request sent by the S-AS for the UE.
  • the context of the first transport layer connection is sent to the T-PSA through the first user plane message.
  • the first user plane message is The message sent immediately after the service response message.
  • a TCP connection is established between the S-PSA and the UE.
  • the S-PSA detects a complete service response message for the service request sent by the UE, the first transmission on the S-PSA
  • the connection state of the layer connection is transferred to the T-PSA, so that the transmission path of the UE can be switched from the TCP connection with the S-PSA to the TCP connection with the T-PSA.
  • the method shown in FIG. 8 can be applied to the UL CL mode.
  • the data transmission path before and after path switching is shown in FIG. 7.
  • the source transport layer proxy network element is an MEC platform network element.
  • the session management network element is SMF
  • the source transport layer proxy network element is S-MEC
  • the target transport layer proxy network element is T-MEC
  • the first application server is S-AS.
  • the second application server is T-AS as an example, and the path switching method is described.
  • Fig. 9 is a schematic flowchart of a path switching method.
  • the first transport layer connection and the third transport layer connection are MPTCP connections
  • the second transport layer connection and the fourth transport layer connection are TCP connections.
  • the method may include S901 to S909, and each step will be described below.
  • S901 When the UE determines that the application needs to initiate a service, it associates a PDU session for the service.
  • the UE associates the PDU session for the service. Otherwise, the UE establishes a PDU session for the service by interacting with the core network, and associates the service with the session.
  • Transport layer messages including messages for establishing a transport layer connection.
  • TCP messages, TCP SYN, SYN+ACK, and ACK messages sent during the TCP three-way handshake must pass
  • the corresponding PDU session is sent from the UE to the PSA via the base station, and then sent from the PSA to the AS in the DN.
  • the service message of the UE is transmitted through the TCP connection, that is, after the service message is encapsulated by the UE into a TCP message based on the parameters of the TCP connection, the PDU session corresponding to the TCP connection is sent from the UE to the AS via the base station and PSA. That is, the transport layer connection between each UE and the server needs to be associated with a PDU session, and the transport layer connection between the UE and the S-PSA or T-PSA involved in this application also needs to be associated with a PDU session.
  • This step is similar to S501. The difference is that in this step, during the PDU session establishment process, the proxy function of the S-MEC does not need to be activated, and the TCP proxy function of the S-MEC can be pre-configured.
  • S902 Establish a first path between the UE and the S-AS.
  • a first transport layer connection that is, an MPTCP connection
  • a second transport layer connection that is, a TCP connection
  • the IP address used by the UE to establish the first path may be allocated and sent to the UE by the S-MEC, or allocated and sent to the UE through the MEC network configuration server.
  • S902 can be implemented in the following ways:
  • the MPTCP connection is established between the S-MEC and the UE based on the MPTCP three-way handshake process, that is, the first transport layer connection between the S-MEC and the UE. details as follows:
  • the SYN message carries a multipath capability MP_CAPABLE option (option), where MP_CAPABLE is used to identify that the local device (ie, UE) supports MPTCP and performs key exchange between the two parties, and j represents a sequence number.
  • S-MEC is pre-configured to support TCP proxy function.
  • the S-MEC receives the ACK message from the UE and completes the three-way handshake with the UE, and the establishment of the first transport layer connection between the UE and the S-MEC is completed.
  • a TCP connection is established between S-MEC and S-AS based on the TCP three-way handshake process, that is, the second transport layer connection between S-MEC and S-AS. details as follows:
  • the execution steps of the above steps can be: 902-b, 902-c and 902-d, 902-e, 902-f can be executed in parallel, that is, 902-b, 902-b and 902-f can be executed in sequence.
  • the process of establishing an MPTCP connection between the UE and the S-MEC is similar to the process of establishing an MPTCP connection between the UE and the S-PSA in S502.
  • the TCP proxy function of S-MEC can be pre-configured instead of being activated according to the instructions of SMF, so the similar step S902-b of S502-b should be: "...Because the TCP proxy has been activated according to the instructions of SMF Function" instead of "...Because the TCP proxy function of S-MEC has been pre-configured" described in S502-b.
  • S903 The SMF sends a DNAI change notification to the S-MEC.
  • the SMF when the SMF detects that the UE is moving and needs to switch the PSA, it sends a DNAI change notification to the S-MEC, and the DNAI change notification includes the target DNAI.
  • S904 The S-MEC sends the context of the first transport layer connection to the T-MEC.
  • the S-MEC may determine the T-MEC according to the target DNAI, and send the context of the first transport layer connection to the T-MEC.
  • the context is the context of the MPTCP connection between the UE and the S-MEC, for example, it may include one or more of the following: the IP address and port number used by the UE for the first transport layer connection, the UE at both ends of the MPTCP connection Key information with S-MEC, hash encryption algorithm information (such as HMAC-SHA256 encryption algorithm), the mapping relationship between DSN and SSN, ISSN and other information.
  • This application can be applied to two modes, namely UL CL mode and SSC mode 3.
  • SMF selects T-PSA and inserts T-PSA as UL CL; for SSC mode 3, SMF triggers the UE to establish a new PDU session with T-PSA as the user plane anchor point.
  • S905 The T-MEC establishes a second path between the UE and the T-AS.
  • the T-MEC establishes a third transport layer connection with the UE according to the context of the first transport layer connection, that is, an MPTCP connection, so that the third transport layer connection and the first transport layer connection belong to the same MPTCP session, and, T-MEC establishes the fourth transport layer connection with T-SA, namely TCP connection.
  • the process of establishing an MPTCP connection between UE and T-MEC is similar to the process of establishing an MPTCP connection between UE and T-PSA in S505 above.
  • the process of establishing a TCP connection between T-MEC and T-AS is similar to that of T-PSA in S505.
  • the process of establishing a TCP connection between PSA and T-AS is similar, so I won’t go into details here.
  • the third transport layer connection is not used as an alternative path to transmit data, and the data is still transmitted on the first transport layer connection.
  • the IP address used by the UE for the second path or the third transport layer connection of the second path may be assigned by S-MEC and sent to the UE, or through MEC Assigned by the network configuration server and sent to the UE.
  • S907 After receiving the third transport layer connection establishment completion message, the S-MEC judges whether it has received a complete service response message sent by the S-AS for the service request sent by the UE.
  • the S-MEC may start to detect the service request message and the service response message after receiving the third transport layer connection establishment completion message sent by the T-MEC in S906.
  • the S-MEC may start to detect the service request message and the service response message after sending the context of the first transport layer connection to the T-MEC in S904.
  • the S-MEC judges whether it has received the complete service response message sent by the S-AS for the service request sent by the UE is the same as the S-PSA in S508 judges whether it has received the S-AS sent for the UE.
  • the way of the complete service response message of the service request is similar, and will not be repeated here.
  • the S-MEC sends first indication information to the UE.
  • S509 is executed by S-PSA, and S908 is executed by S-MEC.
  • S909 The UE switches the data transmission path from the first transmission layer connection to the third transmission layer connection according to the first indication information.
  • S-MEC and T-MEC can respectively establish an MPTCP connection with the UE.
  • the S-MEC detects the complete service for the service request sent by the UE. After responding to the message, the UE switches the data transmission path from the MPTCP connection with the S-MEC to the MPTCP connection with the T-MEC.
  • the method shown in Figure 9 can be applied to two modes, namely SSC mode 3 and UL CL mode.
  • SSC mode 3 the data transmission path before and after path switching is shown in Figure 10.
  • UL CL mode the data transmission path before and after path switching is shown in Figure 11.
  • Fig. 12 is a schematic flowchart of a path switching method.
  • the first transport layer connection, the second transport layer connection, the third transport layer connection, and the fourth transport layer connection are all TCP connections.
  • the method may include S1201 to S1206, and each step will be described below.
  • S1201 When the UE determines that the application needs to initiate a service, it associates a PDU session for the service.
  • S1202 Establish a first path between the UE and the S-AS.
  • a first transport layer connection that is, a TCP connection
  • a second transport layer connection that is, a TCP connection
  • S1202 can be implemented in the following ways:
  • the TCP connection is established between the S-MEC and the UE based on the TCP three-way handshake process, that is, the first transport layer connection between the S-MEC and the UE. details as follows:
  • the S-MEC receives the ACK message from the UE and completes the three-way handshake with the UE, and the establishment of the first transport layer connection between the UE and the S-MEC is completed.
  • a TCP connection is established between S-MEC and S-AS based on the TCP three-way handshake process, that is, the second transport layer connection between S-MEC and S-AS. details as follows:
  • S1203 The SMF sends a DNAI change notification to the S-MEC.
  • the SMF when the SMF detects that the UE is moving and needs to switch the PSA, it sends a DNAI change notification to the S-MEC, and the DNAI change notification includes the target DNAI.
  • S-MEC can determine T-MEC based on the target DNAI.
  • the S-MEC After receiving the DNAI change notification message, the S-MEC determines whether it has received a complete service response message sent by the S-AS for the service request sent by the UE.
  • this step to determine whether the S-MEC has received a complete service response message sent by the S-AS for the service request sent by the UE, it needs to first detect the service request message and the service response message.
  • This application does not limit the time when the S-MEC starts to detect the service request message and the service response message.
  • the S-MEC may start to detect the service request message and the service response message after receiving the DNAI change notification message sent by the SMF in S1203, which is not specifically limited in this application.
  • the S-MEC judges whether it has received the complete service response message sent by the S-AS for the service request sent by the UE is the same as the S-PSA in S508 judges whether it has received the S-AS sent for the UE.
  • the way of the complete service response message of the service request is the same, which will not be repeated here.
  • the S-MEC sends the context of the first transport layer connection to the T-MEC.
  • the context includes a first transport layer connection parameter and a transmission state parameter.
  • the first transport layer connection parameter is used for the generation of the third transport layer connection
  • the transmission state parameter is used to indicate the data transmission of the first transport layer connection. status.
  • the first transport layer connection parameter may include the IP address and/or port number of the UE; optionally, it may also include the IP address and/or port number of the S-AS; or optionally, it may also include the S-PSA The IP address and/or port number used in the first transport layer connection.
  • the transmission state parameters of the first transport layer connection include at least: the TCP sequence number of the uplink data sent on the first transport layer connection, the TCP sequence number of the downlink data sent, and the sequence number of the TCP ACK sent in the uplink and the downlink.
  • the third transport layer connection can be generated, and the third transport layer connection has the same transport layer connection parameters and transmission state parameters as the first transport layer connection.
  • the T-MEC sends the data from the UE to the T-AS through the fourth transport layer connection, that is, the transmission path is switched from the first path to the second path.
  • the context of the first transport layer connection can be carried by the S-MEC in the HTTP response message and sent to the T-PSA, or it can be judged by the S-MEC that it has received the service request sent by the S-AS for the UE.
  • the context of the first connection is sent to the T-MEC through the first user plane message, which is followed by A message sent after the service response message.
  • the fourth transport layer connection is established between the T-MEC and the T-AS.
  • the fourth transport layer connection is a TCP connection.
  • the TCP connection is established between T-MEC and T-AS based on the TCP three-way handshake process, and T-MEC initiates the TCP three-way handshake process.
  • T-MEC initiates the TCP three-way handshake process.
  • this application is not specifically limited. For example, after the application on the T-AS has registered with the T-MEC, the T-MEC and the T-AS will establish a fourth Transport layer connection.
  • the data transmission path is switched from the first path to the second path.
  • a TCP connection is established between the S-MEC and the UE.
  • the S-MEC detects a complete service response message for the service request sent by the UE
  • the TCP connection state on the S-MEC is transferred
  • the transmission path of the UE can be switched from the TCP connection with the S-MEC to the TCP connection with the T-MEC.
  • the method shown in FIG. 12 can be applied to the UL CL mode.
  • the data transmission path before and after path switching is shown in FIG. 11.
  • the session management network element Take the session management network element as SMF, the source transport layer proxy network element as S-PSA, the target transport layer proxy network element as T-PSA, the first application server is S-AS, and the second application server is T-AS as an example.
  • SMF session management network element
  • S-PSA source transport layer proxy network element
  • T-PSA target transport layer proxy network element
  • T-AS first application server
  • T-AS second application server
  • FIG. 13 is a schematic flowchart of another path switching method provided by the present application. The difference between this method and the method shown in Fig. 5 is that in Fig. 5, the S-PSA judges whether a complete service response message sent by the S-AS for the service request sent by the UE is received, and in this method, The UE determines whether a complete service response message sent by the S-AS for the service request sent by the UE is received.
  • the method may include S1301 to S1309, and each step is described below.
  • S1301 to S1306, please refer to S501 to S506, which will not be repeated here.
  • the SMF sends path switching indication information to the UE.
  • the SMF sends path switching indication information to the UE after learning that the third transport layer connection establishment is complete, instructing the UE to perform path switching.
  • S1307 may not be executed. That is, the SMF does not instruct the UE to perform path switching, but the UE autonomously decides to perform path switching. For example, if the establishment of the third transport layer connection is completed, the UE determines that path switching is required.
  • the method for the UE to determine that the third transport layer connection is established is that when the UE establishes the third transport layer connection, it receives the ACK message in the three-way handshake process sent by the T-PSA, and the UE can determine that the third transport layer connection is established. .
  • S1308 The UE judges whether it has received a complete service response message sent by the S-AS for the service request sent by the UE.
  • the UE can determine whether it has received the S-AS sent by parsing the HTTP response message and the HTTP response message. For the complete HTTP response message sent by the UE. For example, the UE can determine whether the HTTP response message is a segmented response response message according to the message status code in the HTTP response message.
  • the HTTP status code carried in the HTTP response message is 200, it means that the HTTP response message is not segmented, and the UE can When the HTTP response message is received, it can be determined that the complete response message of the corresponding HTTP request message has been received; if the HTTP status code carried in the HTTP response message is 206, it means that S-AS sends the UE a segmented response.
  • the UE needs to determine whether the received HTTP response message is the last response message corresponding to the HTTP request message according to the Range field carried in the HTTP request message and the Content-Range field in the HTTP response message.
  • the Range field carried in the HTTP request message is the range used by the UE to inform the S-AS of the requested content
  • the Content-Range field in the HTTP response message is used by the S-AS to inform the range and actual length of the response.
  • the UE switches the data transmission path from the first transport layer connection to the third transport layer connection.
  • S-PSA and T-PSA can respectively establish an MPTCP connection with the UE.
  • the UE detects a complete service response report for the service request sent by the UE. After the text, the UE switches the data transmission path from the MPTCP connection with the S-PSA to the MPTCP connection with the T-PSA.
  • FIG. 13 can be applied in two modes, namely, SSC mode 3 and UL CL mode.
  • SSC mode 3 the data transmission path before and after path switching is shown in Figure 6.
  • UL CL mode the data transmission path before and after path switching is shown in Figure 7.
  • FIG. 14 is a schematic flowchart of another path switching method provided by the present application. The difference between this method and the method shown in Figure 13 is that the source transport layer proxy network element in Figure 13 is S-PSA, the target transport layer proxy network element is T-PSA, and the source transport layer proxy network element in Figure 14 is S-PSA. -MEC, the target transport layer proxy network element is T-MEC.
  • the method may include S1401 to S1409, and each step is described below.
  • the UE determines that path switching is required; otherwise, path switching does not need to be performed.
  • the method for the UE to determine that the third transport layer connection is established is that when the UE establishes the third transport layer connection, it receives the ACK message in the three-way handshake process sent by T-MEC, and the UE can determine that the third transport layer connection is established. .
  • the SMF indicates that the UE needs to perform path switching. Specifically, according to the third transport layer connection establishment completion message, the SMF sends path switching indication information to the UE after learning that the third transport layer connection establishment is completed, instructing the UE to perform path switching.
  • SMF can learn from T-MEC that the establishment of the third transport layer is completed, or it can learn from the AF that the establishment of the third transport layer is completed. At this time, the AF learns from the T-MEC that the establishment of the third transport layer is completed.
  • S1407 The UE judges whether it has received a complete service response message sent by the S-AS for the service request sent by the UE.
  • S1407 can refer to S1308, which will not be described in detail here.
  • S-MEC and T-MEC can respectively establish an MPTCP connection with the UE.
  • the UE detects a complete service response report for the service request sent by the UE. After the text, the UE switches the data transmission path from the MPTCP connection with S-MEC to the MPTCP connection with T-MEC.
  • FIG. 14 can be applied in two modes, namely, SSC mode 3 and UL CL mode.
  • SSC mode 3 the data transmission path before and after path switching is shown in Figure 10.
  • UL CL mode the data transmission path before and after path switching is shown in Figure 11.
  • the session management network element as the SMF
  • the first application server as the S-AS
  • the second application server as the T-AS
  • another path switching method provided by the application is described below.
  • FIG. 15 is a schematic flowchart of another path switching method provided by the present application. As shown in FIG. 15, the method may include S1501 to S1508, and each step is described separately below.
  • S1501 refer to S501.
  • S1502 Establish a first transport layer connection between the UE and the S-AS.
  • the first transport layer connection here may be an MPTCP connection, but this application does not limit it.
  • the process of establishing an MPTCP connection between the UE and the S-AS can refer to the process of establishing an MPTCP connection between the UE and the S-PSA described in S502, which will not be described in detail here.
  • S1503 The S-AS sends the context of the first transport layer connection to the T-AS.
  • the S-AS may send the context of the first transport layer connection to the T-AS when receiving an instruction from the MEC platform network element or the application management network element or the AF.
  • the context of the first transport layer connection may include one or more of the following: the IP address and port number used by the UE for the first transport layer connection, the two ends of the MPTCP connection, namely the UE and S-AS Key information, hash encryption algorithm information, mapping relationship between DSN and SSN, ISSN and other information.
  • the T-AS establishes a second transport layer connection with the UE according to the context of the first transport layer connection.
  • the second transport layer connection here may be an MPTCP connection, but this application does not limit it.
  • the process of establishing an MPTCP connection between the UE and the T-AS can refer to the process of establishing an MPTCP connection between the UE and the T-PSA described in S505, which will not be described in detail here.
  • S1505 The T-AS sends a second transport layer connection establishment complete message to the SMF.
  • the T-AS sends a second transport layer connection establishment complete message to the AF or MEC platform network element, and the AF or MEC platform network element forwards the second transport layer connection establishment complete message to the SMF .
  • the SMF sends path switching indication information to the UE.
  • the SMF can learn that the second transport layer connection establishment is complete, so that it can instruct the UE to perform path switching by sending path switching indication information to the UE.
  • S1507 The UE judges whether it has received a complete service response message sent by the S-AS for the service request sent by the UE.
  • the UE can determine whether it has received the S-AS sent by parsing the HTTP response message and the HTTP response message. For the complete HTTP response message sent by the UE. For example, the UE can determine whether the HTTP response message is a segmented response response message according to the message status code in the HTTP response message.
  • the HTTP status code carried in the HTTP response message is 200, it means that the HTTP response message is not segmented, and the UE can When the HTTP response message is received, it can be determined that the complete response message of the corresponding HTTP request message has been received; if the HTTP status code carried in the HTTP response message is 206, it means that S-AS sends the UE a segmented response.
  • the UE needs to determine whether the received HTTP response message is the last response message corresponding to the HTTP request message according to the Range field carried in the HTTP request message and the Content-Range field in the HTTP response message.
  • the Range field carried in the HTTP request message is the range used by the UE to inform the S-AS of the requested content
  • the Content-Range field in the HTTP response message is used by the S-AS to inform the range and actual length of the response.
  • S1508 The UE switches the data transmission path from the first transport layer connection to the second transport layer connection.
  • the UE determines to perform path switching, if a complete service response message sent by the S-AS for the service request sent by the UE is received, the data transmission path is switched from the first transport layer connection to The second transport layer connection.
  • S1505 and S1506 may not be executed.
  • the UE completes the MPTCP three-way handshake process with the T-AS and establishes the second transport layer connection, if it receives the complete service sent by the S-AS for the service request sent by the UE In response to the message, the UE switches the data transmission path from the first transport layer connection to the second transport layer connection.
  • S-AS and T-AS can respectively establish a transport layer connection with the UE.
  • the UE detects a complete service response to the service request sent by the UE After the message, the UE switches from the transport layer connection with the S-AS to the transport layer connection with the T-AS.
  • FIG. 15 can be applied in two modes, namely, SSC mode 3 and UL CL mode.
  • SSC mode 3 or UL CL mode the data transmission path before and after path switching is shown in Figure 16.
  • the session management network element Take the session management network element as SMF, the first application server is S-AS, the second application server is T-AS, the source transport layer proxy network element is S-PSA, and the target transport layer proxy network element is T-PSA as an example.
  • the path switching method shown in FIG. 17 to FIG. 20 will be described.
  • FIG. 17 is a schematic flowchart of another path switching method provided by the present application. The method 1700 will be described with reference to FIG. 17.
  • S1701 When the UE determines that the application needs to initiate a service, it associates a PDU session for the service.
  • This step is the same as S501, please refer to S501.
  • S1702 Establish a first path between the UE and the S-AS.
  • the first transport layer connection is established between the UE and the S-PSA
  • the second transport layer connection is established between the S-PSA and the S-AS
  • both the first transport layer connection and the second transport layer connection are TCP connections.
  • S1702 is the same as S802.
  • S802 For details, please refer to the description of S802 above.
  • the SMF instructs the T-PSA to establish a TCP connection between the T-PSA and the T-AS, that is, the fourth transport layer connection.
  • the SMF when the SMF detects that the UE is moving and needs to switch the PSA, it selects the T-PSA for the UE and inserts the selected T-PSA as the UL CL.
  • the SMF may send routing information to the selected T-PSA, the routing information instructing the T-PSA to establish a TCP connection with the T-AS.
  • the SMF can send the routing information to the T-PSA through the N4 session modification request message.
  • the routing information may include: IP address information of the T-AS, which is used by the T-PSA to establish a transport layer connection with the T-AS.
  • the SMF may be established through an N4 session The request message or the N4 session modification request message sends the routing information including the IP address information to the T-PSA.
  • a fourth transport layer connection is established between the T-PSA and the T-AS.
  • the T-PSA can obtain the IP address information of the T-AS according to the instructions of the SMF, and then establish a TCP connection with the T-AS based on the TCP three-way handshake process.
  • TCP three-way handshake process initiated by T-PSA refer to 505-d, 505-e, and 505-f in S505 for specific steps, which will not be repeated here.
  • S1705 The SMF sends path switching instruction information to the S-PSA.
  • the SMF may send path switching indication information after determining that the fourth transport layer connection is established.
  • the SMF may send the path switching instruction information to the S-PSA through the N4 session modification request message.
  • the S-PSA After receiving the path switching indication information, the S-PSA judges whether it has received a new service request message sent by the UE.
  • the S-PSA receives the path switching instruction information, and can determine that path switching is required. In this case, the S-PSA judges whether a new service request message sent by the UE is received, and if the result of the determination is yes, it executes S1707 and subsequent steps.
  • the new service request message means that the service request message is not a segmented service request message, or the service request message is a segmented service request message and is the first segment.
  • a complete service request message corresponding to a service request can be divided into multiple segments for transmission, that is, one segment can be transmitted at a time, and the server (for example, S-AS or T-AS in this application) receives all segments After that, it responds; or the server responds to each segment.
  • the server needs to respond to the terminal device according to one or more segments that it has received (for example, the server can respond according to the first segment service request).
  • the first segmented service request reply response indicating that the terminal device can continue to make the later-learned segmentation request; after receiving the second service request, the response will be responded to according to the first segmented service request and the second segmented service request) .
  • the terminal device After receiving the complete response message sent by the server, the terminal device can send a new service request message.
  • the new service request message may be an HTTP request message, which is not limited in this application.
  • S1707 The S-PSA sends the new service request message and the context of the first transport layer connection to the T-PSA.
  • the context of the first transport layer connection is used to transfer the connection state between the UE and the S-PSA to the T-PSA.
  • the context of the first transport layer connection may include the first transport layer connection parameter and the first transmission state parameter, the first transport layer connection parameter is used to generate the third transport layer connection, and the first transmission state parameter is used to indicate The data transmission status of the first transport layer connection.
  • the first transport layer connection parameters may include the IP address and port number used by the UE for the first transport layer connection.
  • it may also include the IP address and/or port number of the S-AS; or optionally, it may also include the IP address and port number used by the S-PSA in the first transport layer connection.
  • the transmission state parameters of the first transport layer connection may include one or more of the following: the TCP sequence number of the uplink data sent on the first transport layer connection, the TCP sequence number of the downlink data sent, or the TCP sequence number of the uplink and downlink sent The sequence number of ACK.
  • the context of the first transport layer connection may be carried by the S-PSA in the HTTP request message and sent to the T-PSA, or after the S-PSA has determined that it has received the new service request message sent by the UE, the S-PSA
  • the PSA sends the new service request message to the T-PSA
  • it sends the context of the first transport layer connection to the T-PSA through the first user plane message, and the first user plane message is immediately following the T-PSA.
  • the TCP proxy function of the S-PSA for the service data flow is deactivated, that is, for the packets of the service data flow, S-PSA no longer performs TCP protocol processing at the transport layer.
  • S1708 The T-PSA generates a third transport layer connection according to the context of the first transport layer connection.
  • the third transport layer connection and the first transport layer connection have the same transport layer connection parameters and transmission state parameters. For the UE, it does not perceive the generation of the third transport layer connection and still considers it to be connected through the first transport layer. transfer data.
  • the data transmission path will be switched from the first path to the second path, that is, the data sent by the UE will be transmitted through the third path
  • the layer connection is sent to the T-PSA, and the T-PSA sends the received information to the T-AS through the fourth transmission layer connection.
  • the second path includes a third transport layer connection and a fourth transport layer connection.
  • T-PSA generating the third transport layer connection can also be understood as T-PSA saving the context of the first transport layer connection.
  • T-PSA sends the new service request message to T-AS.
  • a TCP connection is established between the S-PSA and the UE.
  • the S-PSA determines that path switching is required and detects a new service request message sent by the UE, the S-PSA can be The state of the first transport layer connection is transferred to T-PSA, so that the transmission path of the message can be switched from the path with the S-AS to the path with the T-AS.
  • FIG. 18 is a schematic flowchart of another path switching method provided by the present application. The method 1800 will be described with reference to FIG. 18.
  • S1801 to S1804 are the same as S1701 to S1704, please refer to S1701 to S1704.
  • the SMF is sent to the S-PSA, instructing the S-PSA to transfer the TCP connection state to the T-PSA.
  • the state transition indication information indicates that the S-PSA transitions the connection state between the S-PSA and the UE and the connection state between the S-PSA and the S-AS to the T-PSA.
  • the SMF may select the target T-PSA for the UE and insert the T-PSA as the UL CL when it detects that the UE is moving and needs to switch the PSA. After that, the SMF sends the instruction information to the S-PSA.
  • the SMF may also send the indication information after determining that the establishment of the fourth transport layer connection is completed.
  • the SMF may send the indication information to the S-PSA through the N4 session modification request message.
  • the S-PSA After receiving the instruction information sent by the SMF, the S-PSA transfers the TCP connection state to the T-PSA, that is, the S-PSA sends the context of the first transport layer connection and the context of the second transport layer connection to the T-PSA.
  • the context of the first transport layer connection may include the first transport layer connection parameter and the first transmission state parameter.
  • the first transport layer connection parameter is used to generate the third transport layer connection (the TCP connection between the UE and the T-PSA), and the first transmission state parameter is used to indicate the data transmission state of the first transport layer connection.
  • the first transport layer connection parameters may include the IP address and port number used by the UE for the first transport layer connection.
  • it may also include the IP address and/or port number of the S-AS; or optionally, it may also include the IP address and port number used by the S-PSA in the first transport layer connection.
  • the transmission state parameters of the first transport layer connection may include one or more of the following: the TCP sequence number of the uplink data sent on the first transport layer connection, the TCP sequence number of the downlink data sent, or the TCP sequence number of the uplink and downlink sent The sequence number of ACK.
  • the context of the second transport layer connection may include the second transport layer connection parameter and the second transmission state parameter.
  • the second transport layer connection parameter is used to generate the fifth transport layer connection (TCP connection between T-PSA and S-AS), and the second transmission state parameter is used to indicate the data transmission state of the second transport layer connection.
  • the second transport layer connection parameters may include: the IP address and port number of the S-AS, and optionally, may also include the IP address and/or port number used by the UE for the first transport layer connection.
  • the transmission state parameters of the second transport layer connection can include one or more of the following: the TCP sequence number of the uplink data sent on the second transport layer connection, the TCP sequence number of the downlink data sent, or the TCP ACK sent from the uplink and the downlink The serial number.
  • the T-PSA generates a third transport layer connection according to the context of the first transport layer connection, and generates a fifth transport layer connection according to the context of the second transport layer connection.
  • the third transport layer connection and the first transport layer connection have the same transport layer connection parameters and transmission state parameters. For the UE, it does not perceive the generation of the third transport layer connection and still considers it to be connected through the first transport layer. transfer data.
  • the fifth transport layer connection and the second transport layer connection have the same transport layer connection parameters and transmission state parameters. For the UE, it does not perceive the generation of the fifth transport layer connection and still considers that it is transmitting data through the second transport layer connection.
  • T-PSA generating the third transport layer connection can also be understood as T-PSA saving the context of the first transport layer connection.
  • T-PSA generating the fifth transport layer connection can also be understood as T-PSA saving the context of the second transport layer connection.
  • the message from the UE will be sent to the S-AS through the third path.
  • the third path includes the third transport layer connection and the fifth transport layer connection. Transport layer connection.
  • the message sent by the S-AS to the UE is also sent to the UE through the third path.
  • S1808 The T-PSA judges whether a new service request message sent by the UE is received.
  • T-PSA still transmits service packets through the fifth transport layer connection, that is, transmits service packets through the third path.
  • the new service request message here means that the service request message is not a segmented service request message, or the service request message is a segmented service request message and is the first segment.
  • a complete service request message corresponding to a service request can be divided into multiple segments for transmission, that is, one segment can be transmitted at a time, and the server (for example, S-AS or T-AS in this application) receives all segments After that, it responds; or the server responds to each segment.
  • the server needs to respond to the terminal device according to one or more segments that it has received (for example, the server can respond according to the first segment service request).
  • the first segmented service request reply response indicating that the terminal device can continue to make the later-learned segmentation request; after receiving the second service request, the response will be responded to according to the first segmented service request and the second segmented service request) .
  • the terminal device After receiving the complete response message sent by the server, the terminal device can send a new service request message; or the terminal device can send a new service request message, new service request message, and corresponding response message, new service request message at any time.
  • the subsequent segmented message corresponding to the service request message and the response message corresponding to the segmented message will be transmitted through the second path, and other service request messages and corresponding service response messages will be transmitted through the third path.
  • the T-PSA sends the new service request message to the T-AS through the fourth transport layer connection.
  • the fourth transport layer connection and the third transport layer connection constitute the second path.
  • the T-PSA sending the new service request message to the T-AS through the fourth transport layer connection can also be understood as the T-PSA switching the data transmission path from the first path to the second path.
  • a TCP connection is established between the S-PSA and the UE, and when the S-PSA determines that path switching is required, the TCP connection state on the S-PSA is migrated to the T-PSA.
  • the transmission path of the service request message is switched from the TCP connection between T-PSA and S-AS to T-PSA and T-PSA. TCP connection between ASs.
  • FIG. 19 is a schematic flowchart of another path switching method provided by the present application. The method 1900 will be described with reference to FIG. 19.
  • S1901 to S1906 are the same as S1501 to S1506, please refer to S1501 to S1506.
  • S1907 The UE judges whether the service request message to be sent is a new service request message.
  • the UE judges whether the service request message to be sent satisfies one of the following:
  • the service request message to be sent is a segmented service request message, and is the first segment of the complete service request message corresponding to the service request message to be sent;
  • the service request message to be sent is not a segmented service request message.
  • the UE will send the service request message to be sent through the second transport layer connection. Subsequently, the information between the T-AS and the UE will be transmitted through the second transport layer connection.
  • S1905 and S1906 may not be executed.
  • the UE After the UE completes the MPTCP three-way handshake process with the T-AS to establish the second transport layer connection, if the service request message to be sent is a new service request message, the UE will transfer the data transmission path from the first transport layer The connection is switched to the second transport layer connection.
  • S-AS and T-AS can respectively establish a transport layer connection with the UE.
  • the UE determines that the service request message to be sent is a new service request In the case of a message, the UE switches from the transport layer connection with the S-AS to the transport layer connection with the T-AS.
  • the method shown in FIG. 19 can be applied in two modes, namely, SSC mode 3 and UL CL mode.
  • SSC mode 3 mode or UL CL mode the data transmission path before and after path switching is shown in Figure 16.
  • FIG. 20 is a schematic flowchart of another path switching method provided by the present application. The method 2000 will be described with reference to FIG. 20.
  • S2001 to S2007 are the same as S1301 to S1307, please refer to S1301 to S1307.
  • S2007 may not be executed. That is, the SMF does not instruct the UE to perform path switching, but the UE autonomously decides to perform path switching. For example, if the establishment of the third transport layer connection is completed, the UE determines that path switching is required.
  • the method for the UE to determine that the third transport layer connection is established is that when the UE establishes the third transport layer connection, it receives the ACK message in the three-way handshake process sent by the T-PSA, and the UE can determine that the third transport layer connection is established. .
  • S2008 The UE judges whether the service request message to be sent is a new service request message.
  • the UE judges whether the service request message to be sent satisfies one of the following:
  • the service request message to be sent is a segmented service request message, and is the first segment of the complete service request message corresponding to the service request message to be sent;
  • the service request message to be sent is not a segmented service request message.
  • S2009 The UE switches the data transmission path from the first path to the second path.
  • the UE switches the data transmission path from the first transport layer connection to the third transport layer connection.
  • S-PSA and T-PSA can respectively establish an MPTCP connection with the UE.
  • the UE determines that the service request message to be sent is a new service request message In the case of text, the UE switches from the transport layer connection with the S-AS to the transport layer connection with the T-AS.
  • FIG. 20 can be applied in two modes, namely, SSC mode 3 and UL CL mode.
  • SSC mode 3 the data transmission path before and after path switching is shown in Figure 6.
  • UL CL mode the data transmission path before and after path switching is shown in Figure 7.
  • FIG. 21 is a schematic block diagram of a communication device provided by an embodiment of the present application. As shown in FIG. 17, the communication device 1700 may include a transceiving unit 3100 and a processing unit 3200.
  • the transceiver unit 3100 can be used to receive information (or messages) sent by other devices, and can also be used to send information (or messages) to other devices. For example, sending switching instruction information or receiving switching instruction information.
  • the processing unit 3200 may be used to perform internal processing of the device, such as switching the data transmission path from the first path to the second path.
  • the communication device 3000 may correspond to the source transport layer proxy network element (eg, S-PSA, S-MEC) in the foregoing method embodiment, for example, the communication device 3000 may be the source transport layer proxy
  • the network element may also be a chip in the source transport layer proxy network element.
  • the communication device 3000 may include a unit for performing the operations performed by the source transport layer proxy network element in the foregoing method embodiment, and each unit in the communication device 3000 is used to implement the source transport layer in the foregoing method embodiment. The operation performed by the agent network element.
  • the processing unit 3200 is configured to, if it is determined that path switching is required, after the transceiver unit 3100 receives a complete service response message for the service request sent by the first application server, change the data transmission path from the first path Switch to the second path.
  • the first path is a path established between the terminal device and the first application server, the first path includes a first transport layer connection and a second transport layer connection, and the first transport layer connection is The transmission layer connection between the communication device 3000 and the terminal device, the second transmission layer connection is the transmission layer connection between the communication device 3000 and the first application server, and the second path includes a first The third transmission layer connection and the fourth transmission layer connection, the third transmission layer connection is the transmission layer connection between the target transmission layer proxy network element and the terminal device, and the fourth transmission layer connection is the target transmission layer The transport layer connection between the proxy network element and the second application server.
  • the communication device 3000 may correspond to the target transport layer proxy network element (eg, T-PSA, T-MEC) in the foregoing method embodiment, for example, the communication device 3000 may be the target transport layer proxy
  • the network element may also be a chip in the target transport layer proxy network element.
  • the communication device 3000 may include a unit for performing operations performed by the target transport layer proxy network element in the foregoing method embodiment, and each unit in the communication device 3000 is used to implement the target transport layer in the foregoing method embodiment. The operation performed by the agent network element.
  • the transceiver unit 3100 is configured to receive the context of a first transport layer connection, where the first transport layer connection is a transport layer connection between a source transport layer proxy network element and a terminal device; the processing unit 3200 is configured to, according to The context is to establish a third transport layer connection with the terminal device; after the establishment of the third transport layer connection is completed, the transceiver unit 3100 is used to proxy to the session management network element or the source transport layer The network element sends a third transport layer connection establishment complete message, where the third transport layer connection establishment complete message is used to indicate that the third transport layer connection establishment is complete.
  • the communication device 3000 may correspond to the first application server (for example, S-AS) in the foregoing method embodiment.
  • the communication device 3000 may be the first application server or the first application server.
  • the communication device 3000 may include a unit for performing operations performed by the first application server in the foregoing method embodiment, and each unit in the communication device 3000 is used to implement the operations performed by the first application server in the foregoing method embodiment. Action performed.
  • the communication device 3000 may correspond to the second application server (for example, T-AS) in the foregoing method embodiment.
  • the communication device 3000 may be a second application server or a second application server.
  • the communication device 3000 may include a unit for performing operations performed by the second application server in the foregoing method embodiment, and each unit in the communication device 3000 is used to implement the operations performed by the second application server in the foregoing method embodiment. Action performed.
  • the communication device 3000 may correspond to the session management network element (eg, SMF) in the foregoing method embodiment.
  • the communication device 3000 may be a session management network element or a session management network element.
  • the communication device 3000 may include a unit for performing operations performed by the session management network element in the foregoing method embodiment, and each unit in the communication device 3000 is used to implement the operations performed by the session management network element in the foregoing method embodiment. Action performed.
  • the transceiver unit 3100 is configured to obtain the context of a first transport layer connection, where the first transport layer connection is a transport layer connection between a source transport layer proxy network element and a terminal device; the terminal device needs to be replaced
  • the context of the first transport layer connection is sent to the target transport layer proxy network element, and the context is used for the communication between the target transport layer proxy network element and the terminal device.
  • the establishment of the third transport layer connection is configured to obtain the context of a first transport layer connection, where the first transport layer connection is a transport layer connection between a source transport layer proxy network element and a terminal device; the terminal device needs to be replaced
  • the context of the first transport layer connection is sent to the target transport layer proxy network element, and the context is used for the communication between the target transport layer proxy network element and the terminal device.
  • the establishment of the third transport layer connection is configured to obtain the context of a first transport layer connection, where the first transport layer connection is a transport layer connection between a source transport layer proxy network element and a terminal device; the terminal device needs to
  • the communication device 3000 may correspond to the UE in the foregoing method embodiment.
  • the communication device 3000 may be a UE or a chip in the UE.
  • the communication device 3000 may include a unit for performing operations performed by the UE in the foregoing method embodiment, and each unit in the communication device 3000 is used to implement the operations performed by the UE in the foregoing method embodiment.
  • the processing unit 3200 is configured to, when it is determined that path switching is required, the transceiver unit 3100 switches from the first path to the second path from the data transmission path after receiving a complete service response message for the service request.
  • the first path is a path established between the communication device 3000 and a first application server
  • the first path includes a first transport layer connection and a second transport layer connection
  • the first transport layer connection is The transport layer connection between the source transport layer proxy network element and the communication device 3000
  • the second transport layer connection is the transport layer connection between the source transport layer proxy network element and the first application server
  • the second path includes a third transmission layer connection and a fourth transmission layer connection.
  • the third transmission layer connection is a transmission layer connection between the target transmission layer proxy network element and the communication device 3000.
  • the fourth transmission layer The connection is a transport layer connection between the target transport layer proxy network element and the second application server.
  • a first transport layer connection is established between the communication device 3000 and the first application server
  • a second transport layer connection is established between the communication device 3000 and the second application server.
  • the processing unit 3200 is configured to: when it is determined that path switching is required, the transceiver unit 3100, after receiving a complete service response message for the service request sent by the first application server, transfers the data transmission path from the first transmission
  • the layer connection is switched to the second transport layer connection, and the service request comes from the communication device 3000.
  • the transceiver unit 3100 in the communication device 3000 may correspond to the transceiver 4020 in the terminal device 4000 shown in FIG. 22, and the processing unit 3200 in the communication device 3000 may correspond to The processor 4010 in the terminal device 4000 is shown in FIG. 22.
  • the transceiver unit 3100 in the communication device 3000 may be an input/output interface.
  • the transceiver unit 3100 in the communication device 3000 may correspond to For the communication interface 3010 shown in FIG. 23, the processing unit 3200 may correspond to the processor 3020 shown in FIG. 23.
  • FIG. 21 may be used to perform operations performed by any network element in the foregoing method embodiments.
  • the apparatus shown in FIG. 21 may be used to perform operations performed by any network element in the foregoing method embodiments.
  • FIG. 22 is a schematic structural diagram of a terminal device 4000 provided by an embodiment of the present application.
  • the terminal device 4000 can be applied to the system shown in FIG. 1 to perform the functions of the terminal device (or UE) in the foregoing method embodiment.
  • the terminal device 4000 includes a processor 4010 and a transceiver 4020.
  • the terminal device 4000 further includes a memory 4030.
  • the processor 4010, the transceiver 4002, and the memory 4030 can communicate with each other through an internal connection path to transfer control or data signals.
  • the memory 4030 is used to store computer programs, and the processor 4010 is used to call and connect from the memory 4030. Run the computer program to control the transceiver 4020 to send and receive signals.
  • the terminal device 4000 may further include an antenna 4040 for transmitting the uplink data or uplink control signaling output by the transceiver 4020 through a wireless signal.
  • the foregoing processor 4010 and the memory 4030 may be combined into a processing device, and the processor 4010 is configured to execute the program code stored in the memory 4030 to implement the foregoing functions.
  • the memory 4030 may also be integrated in the processor 4010 or independent of the processor 4010.
  • the processor 4010 can correspond to the processing unit in FIG. 21.
  • the aforementioned transceiver 4020 may correspond to the transceiver unit in FIG. 21.
  • the transceiver 4020 may include a receiver (or called a receiver, a receiving circuit) and a transmitter (or called a transmitter, a transmitting circuit). Among them, the receiver is used to receive signals, and the transmitter is used to transmit signals.
  • terminal device 4000 shown in FIG. 22 can implement various processes involving the terminal device in any method embodiment in the foregoing method embodiments.
  • the operation or function of each module in the terminal device 4000 is to implement the corresponding process in the foregoing method embodiment.
  • the above-mentioned processor 4010 can be used to execute the actions described in the previous method embodiments implemented by the terminal device, and the transceiver 4020 can be used to execute the terminal device described in the previous method embodiments to send or receive from the network device action.
  • the transceiver 4020 can be used to execute the terminal device described in the previous method embodiments to send or receive from the network device action.
  • the aforementioned terminal device 4000 may further include a power supply 4050 for providing power to various devices or circuits in the terminal device.
  • the terminal device 4000 may also include one or more of an input unit 4060, a display unit 4070, an audio circuit 4080, a camera 4090, and a sensor 4100.
  • the audio circuit It may also include a speaker 4082, a microphone 4084, and so on.
  • FIG. 23 is a schematic structural diagram of a communication device according to an embodiment of the present application. It should be understood that the communication device 5000 shown in FIG. 23 is only an example, and the communication device in the embodiment of the present application may further include other modules or units, or include modules with similar functions to the modules in FIG. All modules in 23.
  • the communication device 5000 includes a communication interface 5010 and at least one processor 5020.
  • the communication device 5000 may correspond to any one of a source transport layer proxy network element, a target transport layer proxy network element, a first application server, a second application server, and a session management network element.
  • At least one processor 5020 executes program instructions, so that the communication device 5000 implements the corresponding process of the method executed by the corresponding network element in the foregoing method embodiment.
  • the communication device 5000 may further include a memory.
  • the memory can store program instructions, and at least one processor 5020 can read the program instructions stored in the memory and execute the program instructions.
  • the processor in the embodiment of the present application may be a central processing unit (Central Processing Unit, CPU), and the processor may also be other general-purpose processors, digital signal processors (digital signal processors, DSP), and application specific integrated circuits (application specific integrated circuits). integrated circuit, ASIC), ready-made programmable gate array (field programmable gate array, FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc.
  • the general-purpose processor may be a microprocessor or the processor may also be any conventional processor or the like.
  • the present application also provides a computer program product, the computer program product includes: computer program code, when the computer program code runs on a computer, the computer executes any of the foregoing method embodiments The method on the side of the terminal device.
  • the present application also provides a computer-readable medium storing program code, which when the program code runs on a computer, causes the computer to execute the source in the foregoing method embodiment The method of the transport layer acting on the network element side.
  • the present application also provides a computer-readable medium storing program code, which when the program code runs on a computer, causes the computer to execute the target in the foregoing method embodiment The method of the transport layer acting on the network element side.
  • the present application also provides a computer-readable medium storing program code, which when the program code runs on a computer, causes the computer to execute the first method in the foregoing method embodiments.
  • the present application also provides a computer-readable medium storing program code, which when the program code runs on a computer, causes the computer to execute the first method in the foregoing method embodiments. 2. The method on the application server side.
  • the present application also provides a computer-readable medium storing program code, which when the program code runs on a computer, causes the computer to execute the session in the foregoing method embodiment The method of managing the network element side.
  • the present application also provides a system, which includes the terminal device, the source transport layer proxy network element, the target transport layer proxy network element, and the first application server involved in any of the foregoing method embodiments. , At least one of the second application server and the session management network element.
  • An embodiment of the present application also provides a processing device, including a processor and an interface; the processor is configured to execute the method in any of the foregoing method embodiments.
  • the processing device may be a chip.
  • the processing device may be a field programmable gate array (FPGA), a general-purpose processor, a digital signal processor (digital signal processor, DSP), or an application specific integrated circuit (ASIC) , Ready-made programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, or system on chip (SoC), or central processing
  • the central processor unit (CPU) can also be a network processor (NP), a digital signal processing circuit (digital signal processor, DSP), or a microcontroller (microcontroller unit, MCU) It can also be a programmable logic device (PLD) or other integrated chips.
  • NP network processor
  • DSP digital signal processor
  • MCU microcontroller
  • PLD programmable logic device
  • the methods, steps, and logical block diagrams disclosed in the embodiments of the present application can be implemented or executed.
  • the general-purpose processor may be a microprocessor or the processor may also be any conventional processor or the like.
  • the steps of the method disclosed in the embodiments of the present application can be directly embodied as being executed and completed by a hardware decoding processor, or executed and completed by a combination of hardware and software modules in the decoding processor.
  • the software module can be located in a mature storage medium in the field such as random access memory, flash memory, read-only memory, programmable read-only memory or electrically erasable programmable memory, registers.
  • the storage medium is located in the memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware.
  • the memory in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memory.
  • the non-volatile memory can be read-only memory (ROM), programmable read-only memory (programmable ROM, PROM), erasable programmable read-only memory (erasable PROM, EPROM), and electrically available Erase programmable read-only memory (electrically EPROM, EEPROM) or flash memory.
  • the volatile memory may be random access memory (RAM), which is used as an external cache.
  • RAM random access memory
  • static random access memory static random access memory
  • dynamic RAM dynamic RAM
  • DRAM dynamic random access memory
  • synchronous dynamic random access memory synchronous DRAM, SDRAM
  • double data rate synchronous dynamic random access memory double data rate SDRAM, DDR SDRAM
  • enhanced synchronous dynamic random access memory enhanced SDRAM, ESDRAM
  • synchronous connection dynamic random access memory serial DRAM, SLDRAM
  • direct rambus RAM direct rambus RAM
  • the computer may be implemented in whole or in part by software, hardware, firmware, or any combination thereof.
  • software it can be implemented in the form of a computer program product in whole or in part.
  • the computer program product includes one or more computer instructions.
  • the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices.
  • the computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium.
  • the computer instructions may be transmitted from a website, computer, server, or data center.
  • the computer-readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server or a data center integrated with one or more available media.
  • the available medium may be a magnetic medium (for example, a floppy disk, a hard disk, and a magnetic tape), an optical medium (for example, a high-density digital video disc (digital video disc, DVD)), or a semiconductor medium (for example, a solid state disk (solid state disc, SSD)) etc.
  • the network equipment in each of the above-mentioned device embodiments corresponds completely to the network equipment or terminal equipment in the terminal equipment and method embodiments, and the corresponding modules or units execute the corresponding steps.
  • the communication unit executes the receiving or the terminal equipment in the method embodiments.
  • the processing unit executes the functions of specific units, refer to the corresponding method embodiments. Among them, there may be one or more processors.
  • a component may be, but is not limited to, a process, a processor, an object, an executable file, an execution thread, a program, or a computer running on the processor.
  • the application running on the computing device and the computing device can be components.
  • One or more components can reside in a process or thread of execution, and the components can be located on one computer or distributed between two or more computers.
  • these components can be executed from various computer readable media having various data structures stored thereon.
  • a component can pass a local signal based on a signal having one or more data packets (for example, data from two components that interact with another component in a local system, a distributed system, or a network, such as the Internet that interacts with other systems through a signal). Or remote process to communicate.
  • a signal having one or more data packets for example, data from two components that interact with another component in a local system, a distributed system, or a network, such as the Internet that interacts with other systems through a signal.
  • remote process to communicate for example, data from two components that interact with another component in a local system, a distributed system, or a network, such as the Internet that interacts with other systems through a signal.
  • a corresponding to B means that B is associated with A, and B can be determined according to A.
  • determining B based on A does not mean that B is determined only based on A, and B can also be determined based on A and/or other information.
  • the terminal device and/or the network device can perform some or all of the steps in the embodiments of the present application. These steps or operations are only examples, and the embodiments of the present application may also perform other operations or various operations. Deformation of the operation. In addition, each step may be performed in a different order presented in the embodiment of the present application, and it may not be necessary to perform all the operations in the embodiment of the present application.
  • the disclosed system, device, and method may be implemented in other ways.
  • the device embodiments described above are merely illustrative, for example, the division of the units is only a logical function division, and there may be other divisions in actual implementation, for example, multiple units or components may be combined or It can be integrated into another system, or some features can be ignored or not implemented.
  • the displayed or discussed mutual coupling or direct coupling or communication connection may be indirect coupling or communication connection through some interfaces, devices or units, and may be in electrical, mechanical or other forms.
  • the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the solutions of the embodiments.
  • the functional units in the various embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units may be integrated into one unit.
  • the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer readable storage medium.
  • the technical solution of the present application essentially or the part that contributes to the existing technology or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including Several instructions are used to make a computer device (which may be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in the various embodiments of the present application.
  • the aforementioned storage media include: U disk, mobile hard disk, read-only memory ROM, random access memory RAM, magnetic disk or optical disk and other media that can store program codes.

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Abstract

本申请提供了一种路径切换方法、通信装置和通信系统，终端设备可以分别和源传输层代理网元和目标传输层代理网元之间建立传输层连接，在需要进行路径切换的情况下，源传输层代理网元可以在接收到针对终端设备发送的业务请求的完整的业务应答报文之后，再进行路径切换。由于充分考虑了业务层的状态交互情况，从而能够降低业务的时延，提高用户体验。

Description

路径切换方法、通信装置和通信系统
[根据细则26改正04.02.2020]　
本申请要求于2019年09月06日提交中国专利局、申请号为PCT/CN2019/104809、申请名称为“路径切换方法、通信装置和通信系统”的PCT申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及通信领域，并且更具体地，涉及一种路径切换方法、通信装置和通信系统。
背景技术
在通信系统中，当终端设备从原来的基站的覆盖范围移动至当前的基站的覆盖范围时，会触发空口的切换，即将终端设备的基站从原来的基站切换到当前的基站。虽然终端设备的位置发生了变化，但是此时终端设备仍然接入的是原来的用户面网元，而实际上此时离终端设备最近的用户面网元可能已经发生了变化，但是终端设备仍然与原来的用户面网元进行报文的传输，这种情况下传输路径较长，相应地，报文的传输时延就会变大，影响用户体验。
发明内容
本申请提供了一种路径切换方法、通信装置和通信系统，在路径切换过程中，由于充分考虑了业务层的状态交互情况，从而能够降低业务的时延，提高用户体验。
第一方面，提供了一种路径切换方法，包括：若源传输层代理网元确定需要进行路径切换，所述源传输层代理网元在接收到第一应用服务器发送的针对业务请求的完整的业务应答报文后，将数据传输的路径从第一路径切换到第二路径。
其中，所述第一路径为终端设备与所述第一应用服务器之间建立的路径，所述第一路径包括第一传输层连接和第二传输层连接，所述第一传输层连接为所述源传输层代理网元与所述终端设备之间的传输层连接，所述第二传输层连接为所述源传输层代理网元与所述第一应用服务器之间的传输层连接，所述第二路径包括第三传输层连接和第四传输层连接，所述第三传输层连接为目标传输层代理网元与所述终端设备之间的传输层连接，所述第四传输层连接为所述目标传输层代理网元与第二应用服务器之间的传输层连接。
根据本申请提供的路径切换方法，终端设备可以分别和源传输层代理网元和目标传输层代理网元之间建立传输层连接，在需要进行路径切换的情况下，源传输层代理网元可以在接收到针对终端设备发送的业务请求的完整的业务应答报文之后，将数据传输的路径从终端设备与源传输层代理网元之间的传输层连接切换至与终端设备与目标传输层代理网元之间的传输层连接。这样，可以避免因没有接收到针对终端设备发送的业务请求的完整的业务应答报文，而需要在路径切换后重复发起同样的业务请求的问题。本申请提供的方法由于充分考虑了业务层的状态交互情况，从而能够降低业务的时延，提高用户体验。
本申请中，第一传输层连接可以是多径传输控制协议(multipath transmission control protocol，MPTCP)连接，也可以是传输控制协议(multipath transmission control protocol，TCP)连接，第二传输层连接可以是TCP连接。此外，第一传输层连接也可以是快速UDP互联网连接(Quick UDP Internet Connections，QUIC)，第二传输层连接可以是用户数据报协议(user datagram protocol，UDP)连接。
第三传输层连接可以是MPTCP连接，也可以是TCP连接，第四传输层连接可以是TCP连接。此外，第三传输层连接也可以是快速UDP互联网连接(Quick UDP Internet Connections，QUIC)，第四传输层连接可以是用户数据报协议(user datagram protocol，UDP)连接。其中，如果第一传输层连接是MPTCP连接，第三传输层连接也是MPTCP连接；如果第一传输层连接是TCP连接，第三传输层连接也是TCP连接。
结合第一方面，在第一方面的某些实现方式中，所述将数据传输的路径从所述第一路径切换到第二路径，包括：所述源传输层代理网元指示所述终端设备将所述数据传输的路径从所述第一传输层连接切换至所述第三传输层连接，所述第一传输层连接和所述第三传输层连接为多径传输控制协议(multipath transmission control protocol，MPTCP)连接，所述第一传输层连接和所述第三传输层连接属于同一个MPTCP会话。
从而，终端设备可以根据源传输层代理网元的指示，将数据传输的路径从第一传输层连接切换至第三传输层连接。
结合第一方面，在第一方面的某些实现方式中，所述方法还包括：所述源传输层代理网元向所述目标传输层代理网元发送所述第一传输层连接的上下文，所述上下文用于所述第三传输层连接的建立。
在第一传输层连接建立完成后，源传输层代理网元向目标传输层代理网元发送第一传输层连接的上下文，从而目标传输层代理网元可以建立第三传输层连接。
结合第一方面，在第一方面的某些实现方式中，所述将数据传输的路径从所述第一路径切换到第二路径，包括：所述源传输层代理网元向所述目标传输层代理网元发送所述第一传输层连接的上下文，所述上下文包括第一传输层连接参数和传输状态参数，所述第一传输层连接参数用于所述第三传输层连接的生成，所述传输状态参数用于指示所述第一传输层连接的数据传输状态。
可选地，第一传输层连接和第三传输层连接均为TCP连接。
结合第一方面，在第一方面的某些实现方式中，所述源传输层代理网元指示所述终端设备将所述数据传输的路径从所述第一传输层连接切换至所述第三传输层连接，包括：所述源传输层代理网元调整所述第一传输层连接的优先级，使所述第三传输层连接的优先级高于所述第一传输层连接的优先级。
结合第一方面，在第一方面的某些实现方式中，所述源传输层代理网元向目标传输层代理网元发送所述第一传输层连接的上下文，包括：所述源传输层代理网元通过向会话管理网元发送所述上下文，向所述目标传输层代理网元发送所述上下文。
结合第一方面，在第一方面的某些实现方式中，所述源传输层代理网元确定需要进行路径切换，包括：所述源传输层代理网元接收到所述会话管理网元发送的路径切换指示消息。
结合第一方面，在第一方面的某些实现方式中，所述源传输层代理网元确定需要进行 路径切换，包括：所述源传输层代理网元接收到第三传输层连接建立完成消息，所述第三传输层连接建立完成消息用于指示所述第三传输层连接建立完成。
结合第一方面，在第一方面的某些实现方式中，所述源传输层代理网元和所述目标传输层代理网元均为用户面网元，或者，所述源传输层代理网元和所述目标传输层代理网元均为移动边缘计算(mobile edge computing，MEC)平台网元。
结合第一方面，在第一方面的某些实现方式中，所述源传输层代理网元和所述目标传输层代理网元均为移动边缘计算MEC平台。以及，在所述源传输层代理网元向目标传输层代理网元发送所述第一传输层连接的上下文之前，所述方法还包括：所述源传输层代理网元接收会话管理网元发送的数据网络接入标识(data network access identifier，DNAI)变化通知，所述DNAI变化通知包括目标DNAI；所述源传输层代理网元根据所述目标DNAI，确定所述目标传输层代理网元。
结合第一方面，在第一方面的某些实现方式中，所述上下文包括下述中的一些或多项：所述终端设备用于所述第一传输层连接的互联网协议地址(internet protocol，IP)地址和端口号、所述第一传输层连接使用的哈希加密算法信息、密钥(Key)信息、数据序列号(data seque nce number，DSN)和子流序列号(subflow sequence number，SSN)的映射关系、初始子流序列号(initial subflow sequence number，ISSN)。
结合第一方面，在第一方面的某些实现方式中，所述第一应用服务器和所述第二应用服务器提供相同的应用服务。
第二方面，提供了一种路径切换方法，包括：目标传输层代理网元接收第一传输层连接的上下文，所述第一传输层连接为源传输层代理网元与终端设备之间的传输层连接；所述目标传输层代理网元根据所述上下文，建立与所述终端设备之间的第三传输层连接；在完成所述第三传输层连接的建立后，所述目标传输层代理网元向会话管理网元或所述源传输层代理网元发送第三传输层连接建立完成消息，所述第三传输层连接建立完成消息用于指示所述第三传输层连接建立完成。
根据本申请提供的方法，目标传输层代理网元可以根据第一传输层连接的上下文建立第三传输层连接。从而，在终端设备需要进行路径切换时，可以将数据传输的路径从第一传输层连接切换至第三传输层连接。
结合第二方面，在第二方面的某些实现方式中，所述源传输层代理网元和所述目标传输层代理网元均为用户面网元，或者，所述源传输层代理网元和所述目标传输层代理网元均为移动边缘计算MEC平台网元。
第三方面，提供了一种路径切换方法，包括：会话管理网元获取第一传输层连接的上下文，所述第一传输层连接为源传输层代理网元与终端设备之间的传输层连接；在所述终端设备需要更换协议数据单元(protocol data unit，PDU)会话(session)锚点的情况下，所述会话管理网元向目标传输层代理网元发送所述第一传输层连接的上下文，所述上下文用于所述目标传输层代理网元与所述终端设备之间的第三传输层连接的建立。
根据本申请提供的方法，会话管理网元可以将终端设备与源传输层代理网元之间的第一传输层连接的上下文发送给目标传输层代理网元，从而目标传输层代理网元可以根据该上下文建立与终端设备之间的第三传输层连接。进而，在终端设备需要进行路径切换时，可以将数据传输的路径从第一传输层连接切换至第三传输层连接。
结合第三方面，在第三方面的某些实现方式中，所述方法还包括：在确定所述第三传输层连接建立完成的情况下，所述会话管理网元向所述源传输层代理网元发送路径切换指示信息，所述路径切换指示信息用于指示所述源传输层代理网元将数据传输的路径从所述第一传输层连接切换至所述第三传输层连接。
基于该方案，源传输层代理网元可以根据切换指示信息，确定第三传输层连接建立完成。
结合第三方面，在第三方面的某些实现方式中，所述路径切换指示信息具体用于指示所述源传输层代理网元修改所述第一传输层连接的优先级，以使所述第三传输层连接的优先级大于所述第一传输层连接的优先级。
结合第三方面，在第三方面的某些实现方式中，所述第一传输层连接和所述第三传输层连接为多径传输控制协议MPTCP连接，所述第一传输层连接和所述第三传输层连接属于同一个MPTCP会话。
结合第三方面，在第三方面的某些实现方式中，所述源传输层代理网元和所述目标传输层代理网元均为用户面网元。
第四方面，提供了一种路径切换方法，包括：当终端设备确定需要进行路径切换时，所述终端设备在接收到针对业务请求的完整的业务应答报文后，从数据传输路径从第一路径切换至第二路径。
其中，所述第一路径为所述终端设备与第一应用服务器之间建立的路径，所述第一路径包括第一传输层连接和第二传输层连接，所述第一传输层连接为源传输层代理网元与所述终端设备之间的传输层连接，所述第二传输层连接为所述源传输层代理网元与所述第一应用服务器之间的传输层连接，所述第二路径包括第三传输层连接和第四传输层连接，所述第三传输层连接为目标传输层代理网元与所述终端设备之间的传输层连接，所述第四传输层连接为所述目标传输层代理网元与第二应用服务器之间的传输层连接。
根据本申请提供的路径切换方法，终端设备可以分别和源传输层代理网元和目标传输层代理网元之间建立传输层连接，在需要进行路径切换的情况下，终端设备可以在接收到针对终端设备发送的业务请求的完整的业务应答报文之后，从与源传输层代理网元之间的传输层连接切换至与目标传输层代理网元之间的传输层连接。这样，可以避免因没有接收到针对终端设备发送的业务请求的完整的业务应答报文，而需要在路径切换后重复发起同样的业务请求的问题。本申请提供的方法由于充分考虑了业务层的状态交互情况，从而能够降低业务的时延，提高用户体验。
结合第四方面，在第四方面的某些实现方式中，所述业务应答报文为所述终端设备从所述源传输层代理网元接收的，且所述业务应答报文指示所述第三传输层连接的优先级高于所述第一传输层连接的优先级。
结合第四方面，在第四方面的某些实现方式中，所述终端设备确定需要进行路径切换，包括：所述终端设备接收到所述目标传输层代理网元发送的所述第三传输层连接建立完成消息，所述第三传输层连接建立完成消息用于指示所述第三传输层连接建立完成；或者，所述终端设备接收到会话管理网元发送的路径切换指示信息。
结合第四方面，在第四方面的某些实现方式中，所述第一传输层连接和所述第三传输层连接为多径传输控制协议MPTCP连接，所述第一传输层连接和所述第三传输层连接属 于同一个MPTCP会话。
结合第四方面，在第四方面的某些实现方式中，所述源传输层代理网元和所述目标传输层代理网元均为用户面网元，或者，所述源传输层代理网元和所述目标传输层代理网元均为移动边缘计算MEC平台网元。
结合第四方面，在第四方面的某些实现方式中，所述第一应用服务器和所述第二应用服务器提供相同的应用服务。
第五方面，提供了一种路径切换方法，终端设备与第一应用服务器之间建立有第一传输层连接，所述终端设备与第二应用服务器之间建立有第二传输层连接，所述方法包括：当所述终端设备确定需要进行路径切换，在接收到所述第一应用服务器发送的针对业务请求的完整的业务应答报文后，将数据传输的路径从所述第一传输层连接切换至所述第二传输层连接，所述业务请求来自所述终端设备。
根据本申请提供的路径切换方法，终端设备可以分别和第一应用服务器和第二应用服务器之间建立传输层连接，在需要进行路径切换的情况下，终端设备可以在接收到针对终端设备发送的业务请求的完整的业务应答报文之后，从第一传输层连接切换至第二传输层连接。这样，可以避免因没有接收到针对终端设备发送的业务请求的完整的业务应答报文，而需要在路径切换后重复发起同样的业务请求的问题。本申请提供的方法由于充分考虑了业务层的状态交互情况，从而能够降低业务的时延，提高用户体验。
结合第五方面，在第五方面的某些实现方式中，所述终端设备确定需要进行路径切换，包括：所述终端设备接收到会话管理网元发送的路径切换指示信息。
结合第五方面，在第五方面的某些实现方式中，所述第一传输层连接和所述第二传输层连接为多径传输控制协议MPTCP连接，所述第一传输层连接和所述第三传输层连接属于同一个MPTCP会话上。
结合第五方面，在第五方面的某些实现方式中，所述第一应用服务器和所述第二应用服务器提供相同的应用服务。
第六方面，提供了一种路径切换方法，包括：在源传输层代理网元确定需要进行路径切换的情况下，若所述源传输层代理网元接收到终端设备发送的新的业务请求报文，所述源传输层代理网元向目标传输层代理网元发送所述新的业务请求报文和第一传输层连接的上下文，所述第一传输层连接的上下文用于所述目标传输层代理网元建立第三传输层连接，所述第三传输层连接为所述目标传输层代理网元和所述终端设备之间的传输层连接，其中，所述第一传输层连接为所述终端设备与所述源传输层代理网元之间的传输层连接。
第七方面，提供了一种路径切换方法，包括：目标传输层代理网元接收源传输层代理网元发送的新的业务请求报文和第一传输层连接的上下文；所述目标传输层代理网元通过第四传输层连接，向第二应用服务器发送所述新的业务请求报文，其中，所述第四传输层连接为所述目标传输层代理网元与所述第二应用服务器之间的传输层连接；所述目标传输层代理网元根据所述第一传输层连接的上下文，建立与终端设备之间的第三传输层连接，所述第一传输层连接为所述终端设备与所述源传输层代理网元之间的传输层连接；所述目标传输层代理网元接收所述终端设备通过所述第三传输层连接发送的报文，并通过所述第四传输层连接发送给所述第二应用服务器。
这里，新的业务请求报文是指业务请求报文不是分段业务请求报文，或者，业务请求 报文是分段业务请求报文，且是第一个分段。
应理解，一个业务请求所对应的完整的业务请求报文可以分成多段进行传输，即每次可以传输一个分段，服务器在接收到所有分段后，进行响应；或者服务器针对每个分段进行响应，此时服务器需要根据已经收到的一个或多个分段给终端设备回复响应(例如服务器可以收到第一个分段业务请求后根据第一个分段业务请求回复响应，指示终端设备可以继续发生后学的分段请求；收到第二个业务请求后根据第一个分段业务请求和第二个分段业务请求回复响应)。终端设备接收到服务器发送的完整的响应报文后，可以发送新的业务请求报文。
其中，第一传输层连接和第二传输层连接可以是TCP连接。
根据本申请提供的路径切换方法，源传输层代理网元和终端设备之间建立一条传输层连接，在源传输层代理网元确定需要进行路径切换且检测到终端设备发送的新的业务请求报文后，可以将源传输层代理网元上的第一传输层连接的状态迁移到目标源传输层代理网元，从而可以将报文的传输路径从与第一应用服务器之间的路径切换至与第二应用服务器之间的路径。通过该方法，可以确保一个完整的状态交互过程在同一路径上进行，保证应用迁移过程中应用的超低时延需求。
结合第六方面或第七方面，在某些实现方式中，所述第一传输层连接的上下文包括第一传输层连接参数和第一传输状态参数，所述第一传输层连接参数用于所述第三传输层连接的生成，所述第一传输状态参数用于指示所述第一传输层连接的数据传输状态。
结合第六方面，在第六方面的某些实现方式中，所述源传输层代理网元确定需要进行路径切换，包括：所述源传输层代理网元接收到会话管理网元发送的路径切换指示消息。
结合第七方面，在第七方面的某些实现方式中，在所述目标传输层代理网元通过第四传输层连接，向第二应用服务器发送所述新的业务请求报文之前，所述方法还包括：所述目标传输层代理网元接收会话管理网元发送的第二应用服务器的IP地址信息，并根据所述IP地址信息建立所述第四传输层连接。
第八方面，提供了一种路径切换方法，包括：目标传输层代理网元接收源传输层代理网元发送的第一传输层连接的上下文和第二传输层连接的上下文，所述第一传输层连接为所述源传输层代理网元与终端设备之间的传输层连接，所述第二传输层连接为所述源传输层代理网元与第一应用服务器之间的传输层连接；所述目标传输层代理网元根据所述第一传输层连接的上下文，生成第三传输层连接，并根据所述第二传输层连接的上下文，生成第五传输层连接，所述第三传输层连接为所述目标传输层代理网元与所述终端设备之间的传输层连接，所述第五传输层连接为所述目标传输层代理网元与所述第一应用服务器之间的传输层连接；若所述目标传输层代理网元通过所述第三传输层连接接收到所述终端设备发送的新的业务请求报文，所述目标传输层代理网元将数据传输的路径从第一路径切换到第二路径，其中，所述第一路径为所述终端设备与所述第一应用服务器之间建立的路径，所述第一路径包括所述第三传输层连接和所述第五传输层连接，所述第二路径包括所述第三传输层连接和第四传输层连接，所述第四传输层连接为所述目标传输层代理网元与第二应用述第一传输层连接为所述源传输层代理网元与终端设备之间的传输层连接，所述第二传输层连接为所述源传输层代理网元与第一应用服务器之间的传输层连接，所述第一传输层连接的上下文用于所述目标传输层代理网元生成第三传输层连接，所述第二传输层连接 的上下文用于所述目标传输层代理网元生成第五传输层连接，所述第三传输层连接为所述目标传输层代理网元与所述终端设备之间的传输层连接，所述第五传输层连接为所述目标传输层代理网元与所述第一应用服务器之间的传输层连接。
这里新的业务请求报文是指业务请求报文不是分段业务请求报文，或者，业务请求报文是分段业务请求报文，且是第一个分段。
应理解，一个业务请求所对应的完整的业务请求报文可以分成多段进行传输，即每次可以传输一个分段，服务器(例如，第一应用服务器或第二应用服务器)在接收到所有分段后，进行响应；或者服务器针对每个分段进行响应，此时服务器需要根据已经收到的一个或多个分段给终端设备回复响应(例如服务器可以收到第一个分段业务请求后根据第一个分段业务请求回复响应，指示终端设备可以继续发生后学的分段请求；收到第二个业务请求后根据第一个分段业务请求和第二个分段业务请求回复响应)。终端设备接收到服务器发送的完整的响应报文后，可以发送新的业务请求报文；或者终端设备可以随时发送新的业务请求报文，新的业务请求报文以及对应的响应报文、新的业务请求报文对应的后续分段报文以及分段报文对应的响应报文将通过第二路径传输，其它业务请求报文和对应的业务响应报文将通过第三路径传输。
上述第一传输层连接、第二传输层连接、第三传输层连接、第五传输层连接都可以是TCP连接。
根据本申请提供的方法，源传输层代理网元和终端设备之间建立一条传输层连接，在源传输层代理网元确定需要进行路径切换的情况下，将源传输层代理网元上的传输层连接状态迁移到目标传输层代理网元。并且，在目标传输层代理网元检测到终端设备发送的新的业务请求报文后，将该业务请求报文的传输路径从目标传输层代理网元与第一应用服务器之间的传输层连接切换至与目标传输层代理网元与第二应用服务器之间的传输层连接。通过该方法，可以确保一个完整的状态交互过程在同一路径上进行，保证应用迁移过程中应用的超低时延需求。
结合第八方面，在第八方面的某些实现方式中，在所述目标传输层代理网元将数据传输的路径从第一路径切换到第二路径之前，所述方法还包括：所述目标传输层代理网元从会话管理网元获取所述第二应用服务器的IP地址信息，并根据所述IP地址信息建立所述第四传输层连接。
结合第八方面或第九方面，在某些实现方式中，所述第一传输层连接的上下文包括所述第一传输层连接参数和第一传输状态参数，所述第一传输层连接参数用于所述第三传输层连接的生成，所述第一传输状态参数用于指示所述第一传输层连接的数据传输状态；
所述第二传输层连接的上下文包括所述第二传输层连接参数和第二传输状态参数，所述第二传输层连接参数用于所述第五传输层连接的生成，所述第二传输状态参数用于指示所述第二传输层连接的数据传输状态。
第十方面，提供了一种路径切换方法，包括：在终端设备确定需要进行路径切换的情况下，若待发送的业务请求报文为新的业务请求报文，所述终端设备将数据传输路径从第一传输层连接切换至第二传输层连接，其中，所述第一传输层连接为所述终端设备与第一应用服务器之间的传输层连接，所述第二传输层连接为所述终端设备与所述第二应用服务器之间的传输层连接。
若待发送的业务请求报文为新的业务请求报文，包括：该待发送的业务请求报文为分段业务请求报文，且为该待发送的业务请求报文对应的完整的业务请求报文的第一个分段；或者，该待发送的业务请求报文不为分段业务请求报文。
根据本申请提供的方法，第一应用服务器和第二应用服务器可以分别和终端设备之间建立一条传输层连接，在需要进行路径切换的情况下，若终端设备确定待发送的业务请求报文为新的业务请求报文的情况下，终端设备从与第一应用服务器之间的传输层连接切换至与第二应用服务器之间的传输层连接。通过该方法，可以确保在一个完整的状态交互过程完成后执行路径切换，保证应用迁移过程中应用的超低时延需求。
可选地，所述终端设备确定需要进行路径切换，包括：所述终端设备接收到会话管理网元发送的路径切换指示信息；或者，所述终端设备确定所述第二传输层连接建立完成。
可选地，所述第一传输层连接和所述第二传输层连接为多径传输控制协议MPTCP连接，所述第一传输层连接和所述第三传输层连接属于同一个MPTCP会话。
可选地，所述第一应用服务器和所述第二应用服务器提供相同的应用服务。
第十一方面，提供了一种路径切换方法，包括：在终端设备确定需要进行路径切换的情况下，若待发送的业务请求报文为新的业务请求报文，所述终端设备将从数据传输路径从第一路径切换至第二路径，其中，所述第一路径为所述终端设备与第一应用服务器之间建立的路径，所述第一路径包括第一传输层连接和第二传输层连接，所述第一传输层连接为源传输层代理网元与所述终端设备之间的传输层连接，所述第二传输层连接为所述源传输层代理网元与所述第一应用服务器之间的传输层连接，所述第二路径包括第三传输层连接和第四传输层连接，所述第三传输层连接为目标传输层代理网元与所述终端设备之间的传输层连接，所述第四传输层连接为所述目标传输层代理网元与第二应用服务器之间的传输层连接。
第一传输层连接和第二传输层连接可以是MPTCP连接。
若待发送的业务请求报文为新的业务请求报文，包括：该待发送的业务请求报文为分段业务请求报文，且为该待发送的业务请求报文对应的完整的业务请求报文的第一个分段；或者，该待发送的业务请求报文不为分段业务请求报文。
根据本申请提供的方法，源传输层代理网元和目标传输层代理网元可以分别和终端设备之间建立一条传输层连接，在需要进行路径切换的情况下，若终端设备确定待发送的业务请求报文为新的业务请求报文的情况下，终端设备从与第一应用服务器之间的传输层连接切换至与第二应用服务器之间的传输层连接。通过该方法，可以确保在一个完整的状态交互过程完成后执行路径切换，保证应用迁移过程中应用的超低时延需求。
可选地，所述终端设备确定需要进行路径切换，包括：所述终端设备接收到所述目标传输层代理网元发送的所述第三传输层连接建立完成消息，所述第三传输层连接建立完成消息用于指示所述第三传输层连接建立完成；或者，所述终端设备接收到会话管理网元发送的路径切换指示信息。
可选地，所述第一传输层连接和所述第三传输层连接为多径传输控制协议MPTCP连接，所述第一传输层连接和所述第三传输层连接属于同一个MPTCP会话。
可选地，所述源传输层代理网元和所述目标传输层代理网元均为用户面网元，或者，所述源传输层代理网元和所述目标传输层代理网元均为移动边缘计算MEC平台网元。
可选地，所述第一应用服务器和所述第二应用服务器提供相同的应用服务。
第十二方面，提供了一种路径切换方法，包括：在源传输层代理网元确定需要进行路径切换的情况下，若所述源传输层代理网元接收到终端设备发送的新的业务请求报文，所述源传输层代理网元向目标传输层代理网元发送所述新的业务请求报文和第一传输层连接的上下文，所述第一传输层连接的上下文用于所述目标传输层代理网元建立第三传输层连接，所述第三传输层连接为所述目标传输层代理网元和所述终端设备之间的传输层连接，其中，所述第一传输层连接为所述终端设备与所述源传输层代理网元之间的传输层连接；所述目标传输层代理网元通过第四传输层连接，向第二应用服务器发送所述新的业务请求报文，其中，所述第四传输层连接为所述目标传输层代理网元与所述第二应用服务器之间的传输层连接；所述目标传输层代理网元根据所述第一传输层连接的上下文，建立所述第三传输层连接；所述目标传输层代理网元接收所述终端设备通过所述第三传输层连接发送的报文，并通过所述第四传输层连接发送给所述第二应用服务器。
这里，新的业务请求报文是指业务请求报文不是分段业务请求报文，或者，业务请求报文是分段业务请求报文，且是第一个分段。
应理解，一个业务请求所对应的完整的业务请求报文可以分成多段进行传输，即每次可以传输一个分段，服务器在接收到所有分段后，进行响应；或者服务器针对每个分段进行响应，此时服务器需要根据已经收到的一个或多个分段给终端设备回复响应(例如服务器可以收到第一个分段业务请求后根据第一个分段业务请求回复响应，指示终端设备可以继续发生后学的分段请求；收到第二个业务请求后根据第一个分段业务请求和第二个分段业务请求回复响应)。终端设备接收到服务器发送的完整的响应报文后，可以发送新的业务请求报文。
其中，第一传输层连接和第二传输层连接可以是TCP连接。
根据本申请提供的路径切换方法，源传输层代理网元和终端设备之间建立一条传输层连接，在源传输层代理网元确定需要进行路径切换且检测到终端设备发送的新的业务请求报文后，可以将源传输层代理网元上的第一传输层连接的状态迁移到目标源传输层代理网元，从而可以将报文的传输路径从与第一应用服务器之间的路径切换至与第二应用服务器之间的路径。通过该方法，可以确保一个完整的状态交互过程在同一路径上进行，保证应用迁移过程中应用的超低时延需求。
第十三方面，提供了一种路径切换方法，包括：源传输层代理网元接收会话管理网元发送的状态迁移指示信息；所述源传输层代理网元根据所述状态迁移指示信息，向目标传输层代理网元发送第一传输层连接的上下文和第二传输层连接的上下文，其中，所述第一传输层连接为所述源传输层代理网元与终端设备之间的传输层连接，所述第二传输层连接为所述源传输层代理网元与第一应用服务器之间的传输层连接，所述第一传输层连接的上下文用于所述目标传输层代理网元生成第三传输层连接，所述第二传输层连接的上下文用于所述目标传输层代理网元生成第五传输层连接，所述第三传输层连接为所述目标传输层代理网元与所述终端设备之间的传输层连接，所述第五传输层连接为所述目标传输层代理网元与所述第一应用服务器之间的传输层连接；
所述目标传输层代理网元根据所述第一传输层连接的上下文，生成所述第三传输层连接，并根据所述第二传输层连接的上下文，生成所述第五传输层连接；
若所述目标传输层代理网元通过所述第三传输层连接接收到所述终端设备发送的新的业务请求报文，所述目标传输层代理网元将数据传输的路径从第一路径切换到第二路径，其中，所述第一路径为所述终端设备与所述第一应用服务器之间建立的路径，所述第一路径包括所述第三传输层连接和所述第五传输层连接，所述第二路径包括所述第三传输层连接和第四传输层连接，所述第四传输层连接为所述目标传输层代理网元与第二应用服务器之间的传输层连接。
这里新的业务请求报文是指业务请求报文不是分段业务请求报文，或者，业务请求报文是分段业务请求报文，且是第一个分段。
上述第一传输层连接、第二传输层连接、第三传输层连接、第五传输层连接都可以是TCP连接。
根据本申请提供的方法，源传输层代理网元和终端设备之间建立一条传输层连接，在源传输层代理网元确定需要进行路径切换的情况下，将源传输层代理网元上的传输层连接状态迁移到目标传输层代理网元。并且，在目标传输层代理网元检测到终端设备发送的新的业务请求报文后，将该业务请求报文的传输路径从目标传输层代理网元与第一应用服务器之间的传输层连接切换至与目标传输层代理网元与第二应用服务器之间的传输层连接。通过该方法，可以确保一个完整的状态交互过程在同一路径上进行，保证应用迁移过程中应用的超低时延需求。
第十四方面，提供了一种通信装置，包括用于执行第一方面至第十三方面以及第一方面至第十三方面中任一种可能实现方式中的方法的各个模块或单元。
第十五方面，提供了一种通信装置，包括处理器。该处理器与存储器耦合，可用于执行存储器中的指令，以实现上述第一方面至第十三方面以及第一方面至第十三方面中任一种可能实现方式中的方法。可选地，该通信装置还包括存储器。可选地，该通信装置还包括通信接口，处理器与通信接口耦合。
第十六方面，提供了一种处理器，包括：输入电路、输出电路和处理电路。所述处理电路用于通过所述输入电路接收信号，并通过所述输出电路发射信号，使得所述处理器执行第一方面至第十三方面以及第一方面至第十三方面中任一种可能实现方式中的方法。
在具体实现过程中，上述处理器可以为一个或多个芯片，输入电路可以为输入管脚，输出电路可以为输出管脚，处理电路可以为晶体管、门电路、触发器和各种逻辑电路等。输入电路所接收的输入的信号可以是由例如但不限于接收器接收并输入的，输出电路所输出的信号可以是例如但不限于输出给发射器并由发射器发射的，且输入电路和输出电路可以是同一电路，该电路在不同的时刻分别用作输入电路和输出电路。本申请实施例对处理器及各种电路的具体实现方式不做限定。
第十七方面，提供了一种处理装置，包括处理器和存储器。该处理器用于读取存储器中存储的指令，并可通过接收器接收信号，通过发射器发射信号，以执行第一方面至第十三方面以及第一方面至第十三方面中任一种可能实现方式中的方法。
可选地，所述处理器为一个或多个，所述存储器为一个或多个。
可选地，所述存储器可以与所述处理器集成在一起，或者所述存储器与处理器分离设置。
在具体实现过程中，存储器可以为非瞬时性(non-transitory)存储器，例如只读存储 器(read only memory，ROM)，其可以与处理器集成在同一块芯片上，也可以分别设置在不同的芯片上，本申请实施例对存储器的类型以及存储器与处理器的设置方式不做限定。
应理解，相关的数据交互过程例如发送指示信息可以为从处理器输出指示信息的过程，接收指示信息可以为处理器接收指示信息的过程。具体地，处理器输出的数据可以输出给发射器，处理器接收的输入数据可以来自接收器。其中，发射器和接收器可以统称为收发器。
上述第十七方面中的处理装置可以是一个或多个芯片。该处理装置中的处理器可以通过硬件来实现也可以通过软件来实现。当通过硬件实现时，该处理器可以是逻辑电路、集成电路等；当通过软件来实现时，该处理器可以是一个通用处理器，通过读取存储器中存储的软件代码来实现，该存储器可以集成在处理器中，可以位于该处理器之外，独立存在。
第十八方面，提供了一种计算机程序产品，所述计算机程序产品包括：计算机程序(也可以称为代码，或指令)，当所述计算机程序被运行时，使得计算机执行上述第一方面至第十三方面以及第一方面至第十三方面中任一种可能实现方式中的方法。
第十九方面，提供了一种计算机可读介质，所述计算机可读介质存储有计算机程序(也可以称为代码，或指令)当其在计算机上运行时，使得计算机执行上述第一方面至第十三方面以及第一方面至第十三方面中任一种可能实现方式中的方法。
第二十方面，提供了一种通信系统，包括前述源传输层代理网元、目标传输层代理网元、第一应用服务器、第二应用服务器以及会话管理网元中的至少两个网元。可选地，该通信系统还可以包括前述中的终端设备。
附图说明
图1是应用于本申请的5G系统的架构示意图。
图2是一种PSA切换场景示意图。
图3是MPTCP协议架构示意图。
图4是本申请提供的一种路径切换方法的示意性流程图。
图5是本申请提供的一种路径切换方法的具体示例的示意性流程图。
图6是一种路径切换前后的数据传输的路径的示意图。
图7是另一种路径切换前后的数据传输的路径的示意图。
图8是本申请提供的一种路径切换方法的具体示例的示意性流程图。
图9是本申请提供的一种路径切换方法的具体示例的示意性流程图。
图10是一种路径切换前后的数据传输的路径的示意图。
图11是另一种路径切换前后的数据传输的路径的示意图。
图12是本申请提供的一种路径切换方法的示意性流程图。
图13是本申请提供的一种路径切换方法的示意性流程图。
图14是本申请提供的一种路径切换方法的示意性流程图。
图15是本申请提供的一种路径切换方法的示意性流程图。
图16是一种路径切换前后的数据传输的路径的示意图。
图17是一种路径切换前后的数据传输的路径的示意图。
图18是一种路径切换前后的数据传输的路径的示意图。
图19是一种路径切换前后的数据传输的路径的示意图。
图20是一种路径切换前后的数据传输的路径的示意图。
图21是本申请实施例提供的通信装置的示意性框图。
图22是本申请实施例提供的终端设备的结构示意图。
图23是本申请实施例提供的另一通信装置的示意性框图。
具体实施方式
下面将结合附图，对本申请中的技术方案进行描述。
本申请实施例的技术方案可以应用于各种通信系统，例如：长期演进(long term evolution，LTE)系统、通用移动通信系统(universal mobile telecommunication system，UMTS)、全球互联微波接入(worldwide interoperability for microwave access，WiMAX)通信系统、第五代(5th generation，5G)系统、新无线(new radio，NR)以及随着技术的发展出现的其他新的系统等。
图1示出了一种可以应用于本申请的5G系统的示意图。如图1所示，该系统可以分为接入网和核心网两部分。接入网用于实现无线接入有关的功能，主要包括无线接入网络(radio access network，RAN)设备102。核心网主要包括以下几个关键逻辑网元：用户面功能(user plane function)103、接入和移动管理功能(access and mobility management function，AMF)105、会话管理功能(session management function，SMF)106、策略控制功能(policy control function，PCF)107、统一数据管理功能(unified data management)109。该系统100还可以包括用户设备(user equipment，UE)101、数据网络(data network，DN)104和应用功能(application function，AF)108。各网元之间的接口如图1中所示。应理解，网元之间还可以采用服务化接口进行通信。
UE，也可以称为终端设备。终端设备可以经RAN设备与一个或多个核心网(core network，CN)进行通信。终端设备可称为接入终端、终端、用户单元、用户站、移动站、移动台、远方站、远程终端、移动设备、用户终端、无线网络设备、用户代理或用户装置。终端可以是蜂窝电话、无绳电话、会话启动协议(session initiation protocol，SIP)电话、无线本地环路(wireless localloop，WLL)站、个人数字处理(personal digital assistant，PDA)、具有无线通信功能的手持设备、计算设备或连接到无线调制解调器的其它设备、车载设备、可穿戴设备或物联网、车辆网中的终端设备以及未来网络中的任意形态的终端设备等。
RAN设备，是一种将终端设备接入到无线网络的设备，具体可以为基站。基站可以包括各种形式的基站，例如：宏基站，微基站(也称为小站)，中继站，接入点等。具体可以为：无线局域网(wireless local area network，WLAN)中的接入点(access point，AP)，全球移动通信系统(global system for mobile communications，GSM)或码分多址接入(code division multiple access，CDMA)中的基站(base transceiver station，BTS)，也可以是宽带码分多址(wideband code division multiple access，WCDMA)中的基站(NodeB，NB)，还可以是LTE中的演进型基站(Evolved Node B，eNB或eNodeB)，或者中继站或接入点，或者车载设备、可穿戴设备以及5G系统中的下一代节点B(the next generation Node B， gNB)或者未来演进的公用陆地移动网(public land mobile network，PLMN)网络中的基站等。为方便描述，本申请所有实施例中，将RAN设备统称为基站。
UDM，具备管理用户的签约数据，生成用户的认证信息等功能。
AMF，主要负责UE的注册管理、UE的连接管理、UE的可达性管理、UE的接入授权和接入鉴权、UE的安全功能，UE的移动性管理，网络切片(network slice)选择，SMF选择等功能。AMF作为N1/N2接口信令连接的锚点并为SMF提供N1/N2接口会话管理(session management，SM)消息的路由，维护和管理UE的状态信息。
SMF，主要负责UE会话管理的所有控制面功能，包括UPF的选择与控制，网络互连协议(internet protocol，IP)地址分配及管理，会话的服务质量(quality of service，QoS)管理，从PCF获取策略与计费控制(policy and charging control，PCC)策略等。SMF还作为非接入层(non-access stratum，NAS)消息中SM部分的终结点。
PCF，具备向控制面功能实体提供策略规则等功能。
AF，可以是应用服务器，其可以属于运营商，也可以属于第三方。
UPF，主要负责对用户报文进行处理，如转发、计费等，可以作为协议数据单元(protocol data unit，PDU)会话(session)连接的锚定点，即PDU会话锚点(PDU session anchor，PSA)，负责对UE的数据报文过滤、数据传输/转发、速率控制、生成计费信息、用户面QoS处理、上行传输认证、传输等级验证、下行数据包缓存及下行数据通知触发等。UPF还可以作为多宿主(multi-homed)PDU会话的分支点。
DN，为用户提供数据传输服务的网络，例如，IP多媒体业务(IP Multi-media service,IMS)、互联网等。DN中可以包括应用服务器(application server，AS)，AS是一种软件框架，提供一个应用程序运行的环境，用于为应用程序提供安全、数据、事务支持、负载平衡大型分布式系统管理等服务。UE通过与AS通信获取应用报文。需要说明的是，上述AF为AS的控制面。
应理解，本申请实施例并不限定只应用于图1所示的系统架构中。例如，可以应用本申请实施例的通信方法的通信系统中可以包括更多或更少的网元或设备。图1中的设备或网元可以是硬件，也可以是从功能上划分的软件或者以上二者的结合。图1中的设备或网元之间可以通过其他设备或网元通信。
为了有效满足移动互联网、物联网高速发展所需的高带宽、低时延的要求并减轻网络负荷，移动边缘计算(mobile edge computing，MEC)被提出。具体地，通过将MEC平台网元下沉部署在UPF处，这样可以为UE提供低时延高带宽的服务。MEC平台网元的作用主要是实现应用与网络之间的协同，如：给MEC应用服务器提供MEC应用相关的配置信息使能UE和MEC应用之间的交互，给UE提供MEC应用的相关信息，包括MEC应用的可用性等。MEC平台网元可以与锚点UPF以及应用服务器部署在同一数据中心内。
应理解，MEC平台网元和UPF可以分别作为独立的网元部署，也可以将MEC平台网元的功能部署在UPF上。
需要说明的是，本申请涉及的方案适用部署MEC平台网元的场景。本申请中，MEC平台网元、MEC平台、MEC网元和MEC(如源MEC(source MEC，S-MEC)，目标MEC(target MEC，T-MEC)等)可以相互替换。
在通信系统中，当UE从原来的基站的覆盖范围移动至当前基站的覆盖范围时，会触 发空口的切换，即将UE的基站从原来的基站切换到当前的基站。虽然UE的位置发生了变化，但是此时UE仍然接入的是原来的用户面网元，而实际上此时离UE最近的用户面网元可能已经发生了变化，但是UE仍然与原来的用户面网元进行报文的传输，这种情况下传输路径较长，相应地，报文的传输时延就会变大。为了降低报文的传输时延，有必要将传输路径从原来的用户面网元切换到新的用户面网元，也就是说，要进行PSA切换。
图2示出了PSA切换场景示意图。如图2所示，AS1和AS2可以提供相同的应用服务。当UE从基站1的覆盖范围移动到基站2的覆盖范围时，首先会触发空口切换，切换前用户面数据通过路径1传输，切换后用户面数据通过路径2传输。但此时UE通过基站2接入用户面锚点PSA1，用户面传输路径存在迂回，路径时延增大。对于一些低时延业务，比如在5ms时延需求的典型场景下，如果此时不将锚点从PSA1切换为PSA2，即将用户面传输路径从路径2切换到路径3，仍然采用路径2的话，在UE继续移动的情况下，路径2的时延会进一步增大，导致无法满足5ms的时延需求。为此，需要将用户面传输路径从路径2切换到路径3。
PSA切换可以通过两种PDU会话模式实现：(1)业务和会话连续性模式(service and session continuity mode，SSC mode)3；(2)上行分类器(uplink classofoer，UL CL)。
SSC mode 3是指，当SMF决定需要切换用户面路径时，如果UE移动导致原PDU会话的用户面路径不是最优路径，SMF会请求UE重新建立一个新的到相同DN的PDU会话，SMF为重新建立的PDU会话选择新的PSA，并在定时器到期时或之前业务流已转移到新PDU会话上后，请求UE释放原PDU会话。
UL CL是指：SMF可以在为原PDU会话新增一个新的PSA UPF的同时在原PDU会话的数据传输路径中插入一个UL CL。“UL CL”功能由UPF提供，其目的是将满足业务过滤规则的数据包转发到指定的路径去。当一个具备“UL CL”功能的UPF被插入到一条PDU会话数据通道时，这个PDU会话就可以通过多个PSA，提供接入到同一个DN的多条不同的路径。“UL CL”的功能是传输上行数据到不同的PDU会话锚点中，将下行数据合并传输到UE。一种常见的场景是具有UL CL功能的UPF和新增的锚点UPF合设，即新增的PSA UPF同时具有UL CL的功能。
关于SSC mode 3和UL CL的详细内容，可以参照现有技术。
上述通过SSC mode 3和UL CL进行路径切换的方式，都没有考虑业务层的状态交互情况，从而可能导致业务的时延增大，影响用户体验。
为解决上述问题，本申请提供了多种路径切换方法。这些方法中，源传输层代理网元(比如，PSA UPF或MEC平台网元等)在业务层的一次完整的状态交互之后，再进行路径切换，从而可以降低业务的时延，提高用户体验。
在详细介绍本申请的方法之前，首先对本申请涉及的一些概念作简单介绍。
1、超文本传输协议(hyperText transfer protocol,HTTP)
在该协议中，通过HTTP请求(HTTP request)/HTTP应答(HTTP response)消息，客户端从服务器获取应用数据。
HTTP是无状态应用层协议，即当前的HTTP request请求的内容与之前客户端发送的HTTP request无关。
2、传输控制协议(transmission control protocol，TCP)
TCP是一种面向连接的、可靠的、基于字节流的传输层通信协议。TCP为了保证报文传输的可靠性，给每个包一个序号，同时序号也保证了传送到接收端的包的按序接收。接收端对已成功收到的字节发回一个相应的确认(acknowledgement，ACK)，如果发送端在合理的往返时延(round-trip time，RTT)内未收到确认，那么对应的数据(假设丢失了)将会被重传。
以客户端和服务器之间建立TCP连接为例，对建立TCP连接的流程进行说明。
客户端和服务器基于TCP的三次握手过程建立TCP连接：
(1)客户端向服务器发送TCP同步序列编号(synchronize sequence numbers，SYN)消息，等待服务器确认；
(2)服务器收到TCP SYN消息，回复SYN+ACK消息；
(3)客户端收到SYN+ACK消息，回复另一ACK消息，用来确认已经收到SYN+ACK消息。
3、多径TCP(Multipath TCP，MPTCP)
MPTCP是用于进行多径传输的多径TCP协议，其核心思想是在应用层和传输层之间加入支持多路径传输的Multipath TCP层，以实现多路径传输。
以客户端向服务器发送数据为例，如图3所示，客户端的Multipath TCP层可以将应用层传输的数据分为多个TCP子流，不同TCP子流通过不同网络接口发送至服务器，服务器将不同的TCP子流在MPTCP层进行汇聚后递交至应用层，从而实现客户端和服务器之间的多路径传输。
客户端和服务器之间基于MPTCP三次握手过程建立MPTCP连接：
(1)客户端向服务器端发送一个TCP SYN消息，在MPTCP选项字段里包含了一个MP_CAPABLE选项，该选项中包括客户端的会话秘钥(Key)；
(2)如果服务器支持MPTCP，会返回一个SYN+ACK消息，同样在MPTCP选项字段里包含一个MP_CAPABLE选项，该选项携带服务器端的Key。
(3)客户端返回ACK消息，在MPTCP选项字段里包含一个MP_CAPABLE选项，该选项携带客户端的Key和服务器端的Key。
会话秘钥Key用于客户端和服务器端各自生成一个用来标识客户端和服务器之间的MPTCP会话的令牌(token)。
会话秘钥Key还用于客户端和服务器端生成32位哈希共享秘钥，即基于哈希算法的消息验证码(Hash-based message authentication code，HMAC)，以便作为在该MPTCP会话上建立新的连接的时候客户端和服务器端作为鉴权信息进行验证。因此，在三次握手之后，通信两端都得到了对方的MPTCP会话数据。
4、新建MPTCP连接：
一个MPTCP会话可以有两个(或者两个以上)MPTCP连接。在MPTCP会话里，新建MTPCP连接的过程和三次握手过程类似，不同的是消息中携带的不是MP_CAPABLE选项，而是携带MP_JOIN选项，MP_JOIN可以包含原始会话(连接)的token值和对端的哈希共享密钥，对端的哈希共享密钥用于进行鉴权，原始会话的token值用于指示新生成的MPTCP连接加入原始会话。另外，MP_JOIN还可以包含一个随机数，用来防止重放攻击。MP_JOIN还可以包含发送端的地址，这样即使发送端地址值被进行了网络地址 转换(Network Address Translation，NAT)，对端仍能获得发送端地址。
下面，结合上文所描述的概念，对申请提供的方法进行说明。
应理解，对于下文所描述的任一方法，该方法中的这些步骤或操作仅是示例，在实际操作中为实现该方法还可以执行其他操作或者该方法中一些操作的变形。此外，对于任一附图所示的方法，该方法中的各个步骤可以按照与图中呈现的不同的顺序来执行，并且有可能并非要执行图中的全部操作。
还应理解，本申请中消息的命令或者信息的命令并不对其实际作用构成任何限定。
图4是本申请提供的一种路径切换方法的示意性流程图。如图4所示，该方法可以包括S410至S440，以下对各步骤进行说明。
S410，UE和第一应用服务器之间建立第一路径。
具体地，UE和源传输层代理网元之间建立第一传输层连接，源传输层代理网元和第一应用服务器之间建立第二传输层连接。第一传输层连接和第二传输层连接构成第一路径。可以理解，UE和第一应用服务器之间可以通过第一路径传输用户面数据，或者说，UE和第一应用服务器之间可以通过第一路径进行数据传输。
本申请中，第一传输层连接可以是MPTCP连接，也可以是TCP连接，第二传输层连接可以是TCP连接。关于如何建立MPTCP连接和建立TCP连接，具体可以参照上文或下文相关描述。
此外，第一传输层连接也可以是快速UDP互联网连接(Quick UDP Internet Connections，QUIC)，第二传输层连接可以是用户数据报协议(user datagram protocol，UDP)连接。关于如何建立QUIC和UDP连接，可以参照现有技术。
S420，目标传输层代理网元获取第一传输层连接的上下文。
可选地，第一传输层连接的上下文可以包括UE用于第一传输层连接的IP地址。第一传输层连接还可以包括UE的端口号。
需要说明的是，本申请中提到的IP地址或IP地址信息，可以是互联网协议版本4(Internet Protocol version 4，IPv4)地址或者互联网协议版本6(Internet Protocol version 6，IPv6)前缀。
可选地，第一传输层连接的上下文还可以包括下述中的一项或多项：第一传输层连接的两端(即，UE和源传输层代理网元)的Key信息、哈希加密算法信息(如采用HMAC-SHA256加密算法)、数据序列号(data sequence number，DSN)和子流序列号(subflow sequence number，SSN)之间的映射关系、初始子流序列号(initial subflow sequence number，ISSN)。关于HMAC-SHA256、DSN、SSN和ISSN等的详细内容，可以参照现有技术。
在一种实现方式中，在第一传输层连接建立完成或第一路径建立完成后，源传输层代理网元可以将第一传输层连接的上下文发送给会话管理网元，会话管理网元在检测到UE移动需要切换PSA后，可以将第一传输层连接的上下文发送给目标传输层代理网元。
进一步地，在该实现方式中，源传输层代理网元和目标传输层代理网元都可以是用户面网元，具体为锚点用户面网元，即PSA。在此情况下，源传输层代理网元可以称为源PSA(source PSA，S-PAS)，目标传输层代理网元可以称为目标PSA(target PSA，T-PSA)。
在另一种实现方式中，在第一传输层连接建立完成或第一路径建立完成后，不需要会 话管理网元的转发，源传输层代理网元可以直接将第一传输层连接的上下文发送给目标传输层代理网元。
比如，在第一传输层连接建立完成或第一路径建立完成后，源传输层代理网元或者UE可以向会话管理网元发送第一传输层连接建立完成消息，指示第一传输层连接建立完成。在会话管理网元检测到UE移动需要切换PSA且接收到第一传输层连接建立完成消息后，会话管理网元可以向源传输层代理网元发送数据网络接入标识(data network access identifier，DNAI)变化(change)通知，该DNAI变化通知可以包括目标DNAI。源传输层代理网元根据该目标DNAI可以确定目标传输层代理网元，之后可以将第一传输层连接的上下文发送给目标传输层代理网元。
进一步地，在该实现方式中，源传输层代理网元和目标传输层代理网元都可以是MEC平台网元。并且，在此情况下，MEC平台网元和用户面网元分开部署。本申请中，对应源传输层代理网元的MEC平台网元可以称为源MEC(source MEC，S-MEC)，对应目标传输层代理网元的MEC平台网元可以称为目标MEC(target MEC，T-MEC)。
应理解，会话管理网元可以是SMF，或者可以是具有SMF功能的网元。为便于理解，下文中均以会话管理网元为SMF为例来对本申请提供的方法进行说明。
S430，目标传输层代理网元建立UE和第二应用服务器之间的第二路径。
具体地，目标传输层代理网元建立与UE之间的第三传输层连接，并建立与第二应用服务器之间的第四传输层连接。其中，第三传输层连接可以根据第一传输层连接的上下文建立。第三传输层连接和第四传输层连接构成第二路径。可以理解，UE和第二应用服务器之间可以通过第二路径传输用户面数据。
本申请中，如果第一传输层连接是MPTCP连接，则第三传输层连接也是MPTCP连接，并且第一传输层连接和第三传输层连接属于同一个MPTCP会话；如果第一传输层连接是TCP连接，则第三传输层连接也是TCP连接。如果第二传输层连接是TCP连接，则第四传输层连接可以是TCP连接，但本申请对此不作限定。关于如何建立MPTCP连接和建立TCP连接，具体可以参照上文或下文相关描述。
此外，如果第一传输层连接是QUIC，则第三传输层连接也是QUIC，如果第二传输层连接是UDP连接，则第四传输层连接也是UDP连接。关于如何建立QUIC和UDP连接，可以参照现有技术。
示例性的，第二应用服务器和第一应用服务器可以提供相同的应用服务。第二应用服务器和第一应用服务器可以是同一服务器，也可以是不同的服务器，本申请不做限定。另外，二者可以属于同一DN。
S440，若源传输层代理网元确定需要进行路径切换，在接收到第一应用服务器发送的针对业务请求(或者称，业务请求消息或业务请求报文)的完整的业务应答报文后，将数据传输的路径从第一路径切换到第二路径。其中，该业务请求为UE发送的。
比如，在源传输层代理服务器接收到会话管理网元发送的路径切换指示信息，或接收到第三传输层连接建立完成消息的情况下，若接收到第一应用服务器发送的针对业务请求的完整的业务应答报文，则可以将数据传输的路径从第一路径切换至第二路径。
示例性的，如果业务请求消息为HTTP请求(HTTP request)消息，业务应答消息为HTTP应答(HTTP response)消息，源传输层代理网元可以通过解析HTTP响应消息和 HTTP应答消息来判断是否收到第一应用服务器发送的针对HTTP请求的完整的HTTP应答消息。例如，源传输层代理网元可以根据HTTP应答消息中的消息状态码来判断HTTP应答消息是否是分段应答响应消息，如果HTTP应答消息携带的HTTP状态码是200，则表示HTTP应答消息没有进行分段，源传输层代理网元在收到该HTTP应答消息的时候可以判断已经收到对应的HTTP请求消息的完整的应答消息；如果HTTP应答消息携带的HTTP状态码是206，则表示第一应用服务器通过分段响应的方式给UE发送业务报文，源传输层代理网元需要根据HTTP请求消息中携带的Range字段以及HTTP应答消息中的Content-Range字段来判断所接收的HTTP响应消息是不是HTTP请求消息对应的最后一个段响应消息。其中，HTTP请求消息中携带的Range字段是UE用来告知第一应用服务器请求的内容的范围，HTTP应答消息中的Content-Range字段是第一应用服务器用来告知响应的范围以及实际长度。
示例性的，源传输层代理网元将数据传输的路径从第一路径切换到第二路径具体可以包括：源传输层代理网元向UE发送第一指示信息，该第一指示信息用于UE将数据传输的路径从第一传输层连接切换至第三传输层连接。
比如，源传输层代理网元在判断已经接收到第一应用服务器发送的针对UE发送的业务请求的完整的业务应答报文后，在所述业务应答报文中携带第一指示信息，以便UE收到所述应答报文后，根据该第一指示信息将数据传输的路径从第一传输层连接发送至第三传输层连接。
举例来说，若业务请求消息和业务应答消息分别是HTTP请求消息和HTTP应答消息，源传输层代理网元可以修改针对该HTTP请求消息的HTTP应答消息或最后一段HTTP应答消息的TCP层的MPTCP选项，具体为：源传输层代理网元在对所述HTTP应答消息封装的过程中，设置TCP头中的MP_PRIO option的flag B＝1，这就相当于修改了第一传输层连接的优先级，使其作为备选路径。
应理解，本申请中，源传输层代理网元在接收到切换请求消息或第三传输层连接建立完成消息之后的预设时长内，接收到针对业务请求的完整的业务应答报文，或者在接收到切换请求消息或第三传输层连接建立完成消息之前，接收到针对业务请求的完整的业务应答报文，都可以认为接收到了针对业务请求的完整的业务应答报文。
还应理解，本申请中，针对业务请求的完整的业务应答报文是指，对UE最近一次发送的业务请求的完整的业务应答报文。
根据本申请提供的路径切换方法，UE可以分别和源传输层代理网元和目标传输层代理网元之间建立传输层连接，在需要进行路径切换的情况下，源传输层代理网元可以在接收到针对UE发送的业务请求的完整的业务应答报文之后，再进行路径切换。这样，可以避免因没有接收到针对UE发送的业务请求的完整的业务应答报文，而需要在路径切换后重复发起同样的业务请求的问题。本申请提供的方法由于充分考虑了业务层的状态交互情况，从而能够降低业务的时延，提高用户体验。
下文中，若未作特殊说明，相同术语或词语的含义可以参照上文的描述。
如上所述，源传输层代理网元和目标传输层代理网元可以是PSA，也可以是MEC。也就是说，PSA或者MEC可以集成传输层代理功能，如TCP和MPTCP代理功能。下面分别针对这两种情况，对图4所示的方法的具体流程进行介绍。
下面首先，结合图5至图8，对传输层代理网元为PSA时，图4所示的方法进行更详细的介绍。为便于理解，图5至图8中，以会话管理网元为SMF，源传输层代理网元为源PSA(Source PSA,S-PSA)，目标传输层代理网元为目标PSA(target PSA，T-PSA)，第一应用服务器为源应用服务器(source AS，S-AS)，第二应用服务器为目标AS(target AS，T-AS)为例进行说明。
图5是一种路径切换方法的示意性流程图。在该方法，第一传输层连接和第三传输层连接为MPTCP连接，第二传输层连接和第四传输层连接为TCP连接。如图5所示，该方法可以包括S501至S510，以下分别对各步骤进行说明。
S501，UE在确定应用需要发起业务时，为该业务关联一个PDU会话。
例如，若UE中已经存在满足该业务的QoS需求的PDU会话，则UE为该业务关联该PDU会话。否则，UE通过与核心网交互为该业务建立一个PDU会话，并将该业务关联到该会话。
应理解，本申请中，UE发起业务时，需要先建立传输层连接，以便通过传输层连接发送业务报文或业务数据。传输层的报文，包括建立传输层连接的报文，如以传输层连接为TCP连接为例，TCP报文，在TCP三次握手过程中发送的TCP SYN、SYN+ACK、ACK消息都要通过对应的PDU会话从UE经过基站发送到PSA，再从PSA发送到DN中的AS上。TCP连接建立后，UE的业务报文通过TCP连接传输，即业务报文被UE基于TCP连接的参数封装成TCP报文后，通过TCP连接对应的PDU会话从UE经过基站、PSA发送到AS。即每个UE和服务器之间的传输层连接需要与一个PDU会话关联，本申请中涉及的UE和S-PSA或T-PSA之间的传输层连接也需要与一个PDU会话关联。
可选的，在该PDU会话建立过程中，SMF可以指示S-PSA针对特定的业务数据流(service data flow，SDF)激活TCP代理功能。
可选的，本申请中的UE、传输层代理网元或者SMF对报文执行路径切换，都是针对特定的一个或多个业务数据流执行的。
S502，UE和S-AS之间建立第一路径。
具体地，UE和S-PSA之间建立MPTCP连接，S-PSA和S-AS之间建立TCP连接。
可选的，UE用于建立第一路径的IP地址，可以是PDU会话建立过程中，S-PSA激活TCP代理功能后，给UE分配的。具体可以是：
S-PSA接收SMF发送的指示，针对特定的业务流激活TCP代理功能，并给UE分配用于建立第一路径的传输层连接的IP地址，通过N4会话建立应答消息或者N4会话修改请求消息将该IP地址发送给SMF，SMF通过NAS信令发送给UE。UE后续使用该IP地址发起第一传输层连接的建立。
可选的，UE也可以使用PDU会话的IP地址发起第一传输层连接的建立。
S502可以通过以下方式实现：
1、S-PSA和UE之间基于MPTCP的三次握手过程建立MPTCP连接，即S-PSA和UE之间的第一传输层连接。具体如下：
502-a：UE发起业务时，向S-AS发送TCP SYN消息(syn＝j)，等待S-AS确认。其中SYN消息中携带多径能力MP_CAPABLE选项(option)，其中，MP_CAPABLE用于标识本端设备(即，UE)支持MPTCP且进行双方密钥交互，j表示序号。
502-b：S-PSA收到UE发送的TCP SYN消息后，由于已经根据SMF的指示激活了TCP代理功能，S-PSA会代理S-AS与UE之间建立MPTCP连接，即代理S-AS向UE发送SYN+ACK消息(syn＝k，ack＝j+1)，其中，SYN和ACK消息中携带MP_CAPABLE选项，用来指示S-AS支持MPTCP，k表示序号。
502-c：UE向S-PSA发送ACK消息(ack＝k+1)，用来确认已经收到SYN+ACK消息。S-PSA收到UE的ACK消息，完成与UE的三次握手，UE和S-PSA之间的第一传输层连接建立完成。
2、S-PSA和S-AS之间基于TCP的三次握手过程建立TCP连接，即S-PSA和S-AS之间的第二传输层连接。具体如下：
502-d：S-PSA向S-AS发送TCP SYN消息(syn＝m)，等待S-AS确认，m表示序号；
502-e：S-AS收到TCP SYN消息，回复SYN+ACK消息(syn＝n，ack＝m+1)，其中，n表示序号；
502-f：S-PSA收到SYN+ACK消息，回复ACK消息(ack＝n+1)，用来确认已经收到SYN+ACK消息。
其中，在执行完502-a后，上述步骤的执行步骤可以是：502-b～502-c和502-d～502-f并行执行，即在按序执行502-b、502-c的同时按序执行502-d、502-e、502-f；也可以是按照502-a、502-d、502-e、502-b、502-c、502-f的顺序执行，即S-PSA在接收到S-AS回复是SYN+ACK消息(syn＝n，ack＝m+1)后，再向UE发送SYN+ACK消息(syn＝k，ack＝j+1)，并在收到UE回复的ACK消息(ack＝k+1)后，给S-AS回复ACK消息(ack＝n+1)。
S503，S-PSA向SMF发送第一传输层连接的上下文。
具体地，第一路径或者第一传输层连接建立完成后，S-PSA向SMF发送第一传输层连接的上下文。
示例性的，S-PSA可以通过N4会话修改请求消息向SMF发送第一传输层连接的上下文。该上下文为UE和S-PSA之间的MPTCP连接的上下文，例如可以包括下述中的一项或多项：UE用于第一传输层连接的IP地址和端口号、MPTCP连接两端的即UE和S-PSA的Key信息、哈希加密算法信息(如采用HMAC-SHA256加密算法)、DSN和SSN之间的映射关系和ISSN等信息。
S504，SMF向T-PSA发送第一传输层连接的上下文。
具体地，SMF检测到UE移动需要切换PSA的情况下，为UE选择T-PSA，并向所选择的T-PSA发送第一传输层连接的上下文。
示例性的，SMF可以通过N4会话修改请求消息向T-PSA发送所述上下文，在发送所述上下文的同时，SMF还可以指示T-PSA针对特定的SDF激活TCP代理功能。
示例性的，SMF可以根据UE的位置为UE选择目标T-PSA。
本申请可以应用于两种模式，即UL CL模式和SSC mode 3。对于UL CL模式，SMF选择T-PSA后，插入T-PSA作为UL CL；对于SSC mode 3，SMF触发UE建立一个新的PDU会话，该PDU会话以T-PSA作为用户面锚点。作为S503至S504的一种替代方式，S-PSA可以直接向T-PSA发送第一传输层连接的上下文。例如可以通过在S-PSA与T-PSA之间建立用户面隧道来传输所述上下文。
可选的，SMF还向T-PSA发送T-AS的IP地址信息，该IP地址信息用于T-PSA建 立与T-AS之间的传输层连接，它可以是IPv4地址，示例性的，SMF可以通过N4会话建立请求消息或N4会话修改请求消息向T-PSA发送该的IP地址信息。
S505，T-PSA建立UE和T-AS之间的第二路径。
具体地，T-PSA根据第一传输层连接的上下文建立与UE之间的MPTCP连接，即第三传输层连接，使得第三传输层连接和第一传输层连接属于同一个MPTCP会话，并且，T-PSA建立与T-SA之间的TCP连接，即第四传输层连接。
其中，T-PSA和UE之间基于MPTCP的三次握手过程建立MPTCP连接，即T-PSA和UE之间的第三传输层连接。具体如下：
505-a：T-PSA向UE发送TCP SYN消息(syn＝p)，等待UE确认；其中SYN消息中携带MP_JOIN选项，其中，MP_JOIN选项中可以携带T-PSA在步骤504中获取的上下文中的UE的token值，T-PSA的IP地址，T-PSA本地的随机数，p表示序号；
505-b：UE收到T-PSA发送的TCP SYN消息后，向T-PSA发送SYN+ACK消息(syn＝q，ack＝p+1)，其中，SYN+ACK包中携带MP_JOIN选项，中，MP_JOIN选项中携带UE的HMAC，UE本地的随机数，UE的IP地址，q表示序号；
505-c：T-PSA向UE发送ACK消息(ack＝p+1)，用来确认已经收到SYN+ACK消息。UE收到T-PSA发送的ACK消息，完成与T-PSA的三次握手，UE和T-PSA之间的第三传输层连接建立完成。
T-PSA和T-AS之间基于TCP的三次握手过程建立TCP连接，即T-PSA和T-AS之间的第四传输层连接。具体如下：
505-d：T-PSA向T-AS发送TCP SYN消息(syn＝s)，等待T-AS确认，s表示序号；
505-e：T-AS收到TCP SYN消息，回复SYN+ACK消息(syn＝t，ack＝s+1)，其中，t表示序号；
505-f：T-PSA收到SYN+ACK消息，回复ACK消息(ack＝t+1)，用来确认已经收到SYN+ACK消息。
上述步骤中的执行步骤505-a至505-c和505-d至505-f是独立执行的，即在按序执行505-a、505-b、505-c的同时按序执行505-d、505-e、505-f；也可以是先按序执行505-a、505-b、505-c，再按序执行505-d、505-e、505-f；或先按序执行505-d、505-e、505-f，再按序执行505-a、505-b、505-c，本申请不做限定。
在建立第三传输层连接时，T-PSA发起的TCP SYN消息中(即步骤505-a)可以将MP_JOIN option的flag的最后一个bit位设置为B＝1，以指示新建子流是备选路径backup path，即此时在第一传输层连接可用的情况下，第三传输层连接作为备选路径不用来传输数据，数据还是在第一传输层连接上传输。
可选的，对于UL CL模式或SSC mode 3，UE用于第二路径或第二路径的第三传输层连接的IP地址，可以是T-PSA给UE分配的。具体可以是：T-PSA接收到第一传输层连接的上下文以后，给UE分配用于第二路径的传输层连接的IP地址，T-PSA将该IP地址发送给SMF，SMF通过NAS信令发送给UE。具体的，T-PSA可以通过步骤S504中的N4会话建立请求消息对应的N4会话建立应答消息将该IP地址发送给SMF，也可以通过N4会话修改请求消息将该IP地址发送给SMF。需要说明的是，T-PSA在5-505a中使用的目的IP地址为UE分配的该IP地址。
可选的，UE用于第二路径或第二路径的第三传输层连接的IP地址，也可以是PDU会话的IP地址。
S506，第三传输层连接建立完成后，T-PSA向SMF发送第三传输层连接建立完成消息。
S507，SMF向S-PSA发送路径切换指示信息。
SMF根据第三传输层连接建立完成消息，获知第三传输层连接建立完成后，向S-PSA发送路径切换指示信息，指示S-PSA进行路径切换。
S508，S-PSA收到路径切换指示信息后，判断是否接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文。
若确定结果为是，则执行S509，否则，不执行S509以及后续步骤。
在该步骤中，S-PSA要判断是否接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文，需要先检测业务请求报文和业务应答报文。对于S-PSA开始检测业务请求报文和业务应答报文的时间，本申请不做限定。例如，S-PSA可以在收到SMF在S507发送的路径切换指示信息后开始检测业务请求报文和业务应答报文。再如，S-PSA可以在S503中向SMF发送第一传输层连接的上下文之后开始检测业务请求报文和业务应答报文。又如，S-PSA可以在接收到SMF发送的第二指示信息后，开始检测业务请求报文和业务应答报文，其中第二指示信息用于指示S-PSA开始检测业务请求报文和业务应答报文。示例性的，SMF给S-PSA发送第二指示信息的时机，可以是在S506收到T-PSA发送的第三传输层连接建立完成消息时，也可以是在SMF检测到UE移动需要切换PSA的情况下，还可以是在SMF通过步骤S504向T-PSA发送第一传输层连接的上下文后，本申请不做具体限定。
示例性的，如果业务请求消息为HTTP请求(HTTP request)消息，业务应答消息为HTTP应答(HTTP response)消息，S-PSA可以通过解析HTTP响应消息和HTTP应答消息来判断是否收到S-AS发送的针对UE发送的完整的HTTP应答消息。比如，S-PSA可以根据HTTP应答消息中的消息状态码来判断HTTP应答消息是否是分段应答响应消息，如果HTTP应答消息携带的HTTP状态码是200，则表示HTTP应答消息没有进行分段，S-PSA可以在收到该HTTP应答消息的时候可以判断已经收到对应的HTTP请求消息的完整的应答消息；如果HTTP应答消息携带的HTTP状态码是206，则表示S-AS通过分段响应的方式给UE发送业务报文，S-PSA需要根据HTTP请求消息中携带的Range字段以及HTTP应答消息中的Content-Range字段来判断所接收的HTTP响应消息是不是HTTP请求消息对应的最后一个段响应消息。其中，HTTP请求消息中携带的Range字段是UE用来告知S-AS请求的内容的范围，HTTP应答消息中的Content-Range字段是S-AS用来告知响应的范围以及实际长度。
S509，S-PSA向UE发送第一指示信息，该第一指示信息用于UE将数据传输的路径从第一传输层连接切换至第三传输层连接。
具体来讲，S-PSA在判断已经接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文后，在所述业务应答报文中携带第一指示信息，以便UE收到所述应答报文后，根据该第一指示信息将数据传输的路径从第一传输层连接切换至第三传输层连接。
比如，若业务请求消息和业务应答消息分别是HTTP请求消息和HTTP应答消息， S-PSA可以修改针对该HTTP请求消息的HTTP应答消息或最后一段HTTP应答消息的TCP层的MPTCP选项，具体为：S-PSA在将所述HTTP应答消息封装的过程中，设置TCP头中的MP_PRIO option的flag B＝1，即修改所述第一传输层连接的优先级，使其作为备选路径。
S510，UE根据第一指示信息，将数据传输的路径从第一传输层连接切换至第三传输层连接。
比如，UE接收所述业务应答消息后，根据所述业务应答消息中的MPTCP选项的MP_PRIO option中的flag B的值，确定将数据传输的路径从第一传输层连接切换至第三传输层连接。
根据本申请提供的方法，S-PSA和T-PSA可以分别和UE之间建立一条MPTCP连接，在需要进行路径切换的情况下，在S-PSA检测到针对UE发送的业务请求的完整的业务应答报文后，UE将数据传输的路径从与S-PSA之间的MPTCP连接切换至与T-PSA之间的MPTCP连接。通过该方法，可以确保在一个完整的状态交互过程完成后执行路径切换，保证应用迁移过程中应用的超低时延需求。
图5所示的方法可以应用两种模式，即上文在对S504进行说明时所提到的SSC mode 3和UL CL模式。针对SSC mode 3模式，路径切换前后的数据传输的路径如图6所示。针对UL CL模式，路径切换前后的数据传输的路径如图7所示。
图8是一种路径切换方法的示意性流程图。在该方法，第一传输层连接、第二传输层连接、第三传输层连接和第四传输层连接都为TCP连接。如图8所示，该方法可以包括S801至S806，以下分别对各步骤进行说明。
S801，UE在确定应用需要发起业务时，为该业务关联一个PDU会话。
这个步骤可以参考S501，此处不再赘述。
S802，UE和S-AS之间建立第一路径。
具体地，UE和S-PSA之间建立第一传输层连接，S-PSA和S-AS之间建立第二传输层连接，第一传输层连接和第二传输层连接都为TCP连接。
S802可以通过以下方式实现：
1、S-PSA和UE之间基于TCP的三次握手过程建立TCP连接，即S-PSA和UE之间的第一传输层连接。具体如下：
802-a：UE发起业务时，向S-AS发送TCP SYN消息(syn＝j)，等待S-AS确认，其中，j表示序号。
802-b：S-PSA收到UE发送的TCP SYN消息后，由于已经根据SMF的指示激活了TCP代理功能，代理S-AS与UE之间建立TCP连接，即代理S-AS向UE发送SYN+ACK消息(syn＝k，ack＝j+1)，其中，k表示序号。
802-c：UE向S-PSA发送ACK消息(ack＝k+1)，用来确认已经收到SYN+ACK消息。S-PSA收到UE的ACK消息，完成与UE的三次握手，UE和S-PSA之间的第一传输层连接建立完成。
2、S-PSA和S-AS之间基于TCP的三次握手过程建立TCP连接，即S-PSA和S-AS之间的第二传输层连接。具体如下：
802-d：S-PSA向S-AS发送TCP SYN消息(syn＝m)，等待S-AS确认，m表示序号。
802-e：S-AS收到TCP SYN消息，回复SYN+ACK消息(syn＝n，ack＝m+1)，其中，n表示序号。
802-f：S-PSA收到SYN+ACK消息，回复ACK消息(ack＝n+1)，用来确认已经收到SYN+ACK消息。
其中，在执行完802-a后，上述步骤的执行顺序可以是：802-b至802-c和802-d至、802-f可以并行执行，即在按序执行802-b、802-c的同时按序执行802-d、802-e、802-f；也可以是按照802-a、802-d、802-e、802-b、802-c、802-f的顺序执行，即S-PSA在接收到S-AS回复的SYN+ACK消息(syn＝n，ack＝m+1)后，再向UE发送SYN+ACK消息(syn＝k，ack＝j+1)，并在收到UE回复的ACK消息(ack＝k+1)后，给S-AS回复ACK消息(ack＝n+1)。
S803，SMF向T-PSA发送路由信息，路由信息指示T-PSA建立与T-AS之间的TCP连接，即第四传输层连接。
具体地，SMF检测到UE移动需要切换PSA的情况下，为UE选择T-PSA，并给T-PSA发送N6接口的路由信息。T-PSA根据该路由信息，和T-AS之间建立第四传输层连接。
可选的，所述路由信息还包括：T-AS的IP地址信息，该IP地址信息用于T-PSA建立与T-AS之间的传输层连接，示例性的，SMF可以通过N4会话建立请求消息或N4会话修改请求消息向T-PSA发送包括该的IP地址信息的路由信息。
S804，T-PSA和T-AS之间建立第四传输层连接。
具体的，第四传输层连接为TCP连接。T-PSA和T-AS之间基于TCP的三次握手过程建立TCP连接，由T-PSA发起TCP三次握手过程，具体步骤参考S505中的505-d、505-e、和505-f，本处不再赘述。
S805，SMF向S-PSA发送路径切换指示信息。
示例性的，SMF可以在检测到UE移动需要切换PSA的情况下，为UE选择目标T-PSA，并插入T-PSA作为UL CL。之后，SMF向S-PSA发送路径切换指示信息。
可选地，SMF也可以在确定第四传输层连接建立完成后发送路径切换指示信息。
示例性的，SMF可以通过N4会话修改请求消息向S-PSA发送该路径切换指示信息。
可选的，SMF在插入T-PSA作为UL CL后，还指示T-PSA建立与T-AS之间的第四传输层连接，即TCP连接。比如，SMF可以通过N4会话修改请求消息向T-PSA发送指示T-PSA建立与T-AS之间的第四传输层连接的指示信息。
S806，S-PSA收到路径切换指示信息后，判断是否接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文。
若确定结果为是，则执行S807，否则，不执行S807。
在该步骤中，S-PSA要判断是否接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文，需要先检测业务请求报文和业务应答报文。对于S-PSA开始检测业务请求报文和业务应答报文的时间，本申请不做限定。例如，S-PSA可以在收到SMF在S804发送的路径切换指示信息后开始检测业务请求报文和业务应答报文；再如，S-PSA在接收到SMF发送的第二指示信息后，开始检测业务请求报文和业务应答报文，示例性的，SMF给S-PSA发送第二指示信息的时机，可以是在SMF检测到UE移动需要切换PSA的情况下，本申请不做具体限定。
示例性的，S-PSA判断是否接收到S-AS发送的针对UE发送的业务请求的完整的业 务应答报文的方式与S508中S-PSA判断是否接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文的方式相同，这里不再赘述。
S807，S-PSA向T-PSA发送第一传输层连接的上下文。
该上下文包括第一传输层连接参数和传输状态参数，所述第一传输层连接参数用于所述第三传输层连接的生成，所述传输状态参数用于指示第一传输层连接的数据传输状态。其中，第一传输层连接参数包括：UE用于第一传输层连接的IP地址和端口号，可选的，还包括S-AS的IP地址，端口号；或者可选的，还包括S-PSA在第一传输层连接使用的IP地址和端口号。第一传输层连接的传输状态参数至少包括：第一传输层连接上上行数据已发送的TCP序号，下行数据已发送的TCP序号，上下行已发送的TCP ACK的序号。
也就是说，根据S-PSA向T-PSA发送所述上下文，可以生成第三传输层连接，第三传输层连接与第一传输层连接有相同的传输层连接参数和传输状态参数，对于UE来说，不感知第三传输层连接的生成，仍然认为在通过第一传输层传输数据。第三传输层连接生成后，T-PSA将来自UE的数据通过第四传输层连接发送给T-AS，即传输路径从第一路径切换至第二路径。
示例性的，第一传输层连接的上下文可以由S-PSA携带在HTTP响应消息中发送给T-PSA，也可以在S-PSA判断已经接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文后，在S-PSA将业务应答报文发送后，将第一传输层连接的上下文通过第一用户面报文发送给T-PSA，所述第一用户面报文是紧跟在所述业务应答报文之后发送的报文。
根据本申请提供的方法，S-PSA和和UE之间建立一条TCP连接，在S-PSA检测到针对UE发送的业务请求的完整的业务应答报文后，将S-PSA上的第一传输层连接的连接状态迁移到T-PSA，使得UE的传输路径可以从与S-PSA之间的TCP连接切换至与T-PSA之间的TCP连接。通过该方法，可以确保在一个完整的状态交互过程完成后执行路径切换，保证应用迁移过程中应用的超低时延需求。
图8所示的方法可以应用到UL CL模式，针对该模式，路径切换前后的数据传输的路径如图7所示。
下面结合图9至图12，对源传输层代理网元为MEC平台网元时，图4所示的方法进行更详细的介绍。为便于理解，图9至图12中，以会话管理网元为SMF，源传输层代理网元为S-MEC，目标传输层代理网元为T-MEC，第一应用服务器为S-AS，第二应用服务器为T-AS为例，对路径切换方法进行说明。
图9是一种路径切换方法的示意性流程图。在该方法，第一传输层连接和第三传输层连接为MPTCP连接，第二传输层连接和第四传输层连接为TCP连接。如图9所示，该方法可以包括S901至S909，下面分别对各步骤进行说明。
S901，UE在确定应用需要发起业务时，为该业务关联一个PDU会话。
例如，若UE中已经存在满足该业务的QoS需求的PDU会话，则UE为该业务关联该PDU会话。否则，UE通过与核心网交互为该业务建立一个PDU会话，并将该业务关联到该会话。
应理解，本申请中，UE发起业务时，需要先建立传输层连接，以便通过传输层连接发送业务报文或业务数据。传输层的报文，包括建立传输层连接的报文，如以传输层连接 为TCP连接为例，TCP报文，在TCP三次握手过程中发送的TCP SYN、SYN+ACK、ACK消息都要通过对应的PDU会话从UE经过基站发送到PSA，再从PSA发送到DN中的AS上。TCP连接建立后，UE的业务报文通过TCP连接传输，即业务报文被UE基于TCP连接的参数封装成TCP报文后，通过TCP连接对应的PDU会话从UE经过基站、PSA发送到AS。即每个UE和服务器之间的传输层连接需要与一个PDU会话关联，本申请中涉及的UE和S-PSA或T-PSA之间的传输层连接也需要与一个PDU会话关联。
该步骤与S501类似，不同之处在于，在该步骤中，在PDU会话建立过程中，不需要激活S-MEC的代理功能，S-MEC的TCP代理功能可以预配置。
S902，UE和S-AS之间建立第一路径。
具体地，UE和S-MEC之间建立第一传输层连接，即MPTCP连接，S-MEC和S-AS之间建立第二传输层连接，即TCP连接。
可选的，UE用于建立第一路径的IP地址，可以是S-MEC分配并发送给UE的，也可以是通过MEC网络配置服务器分配并发送给UE的。
S902可以通过以下方式实现：
1、S-MEC和UE之间基于MPTCP的三次握手过程建立MPTCP连接，即S-MEC和UE之间的第一传输层连接。具体如下：
902-a：UE发起业务时，向S-AS发送TCP SYN消息(syn＝j)，等待S-AS确认。其中SYN消息中携带多径能力MP_CAPABLE选项(option)，其中，MP_CAPABLE用于标识本端设备(即，UE)支持MPTCP且进行双方密钥交互，j表示序号。
902-b：S-MEC收到UE发送的TCP SYN消息后，代理S-AS与UE之间建立MPTCP连接，即代理S-AS向UE发送SYN+ACK消息(syn＝k，ack＝j+1)，其中，SYN+ACK消息中携带MP_CAPABLE选项，用来指示S-AS支持MPTCP，k表示序号。S-MEC预配置支持TCP代理功能。
902-c：UE向S-MEC发送ACK消息(ack＝k+1)，用来确认已经收到SYN和ACK消息。S-MEC收到UE的ACK消息，完成与UE的三次握手，UE和S-MEC之间的第一传输层连接建立完成。
2、S-MEC和S-AS之间基于TCP的三次握手过程建立TCP连接，即S-MEC和S-AS之间的第二传输层连接。具体如下：
902-d：S-MEC向S-AS发送TCP SYN消息(syn＝m)，等待S-AS确认，m表示序号；
902-e：S-AS收到TCP SYN消息，回复SYN+ACK消息(syn＝n，ack＝m+1)，其中，n表示序号；
902-f：S-MEC收到SYN+ACK消息，回复ACK消息(ack＝n+1)，用来确认已经收到SYN+ACK消息。
其中，在执行完902-a后，上述步骤的执行步骤可以是：902-b、902-c和902-d、902-e、902-f可以并行执行，即在按序执行902-b、902-c的同时按序执行902-d、902-e、902-f；也可以是按照902-a、902-d、902-e、902-b、902-c、902-f的顺序执行，即S-MEC在接收到S-AS回复是SYN+ACK消息(syn＝n，ack＝m+1)后，再向UE发送SYN+ACK消息(syn＝k，ack＝j+1)，并在收到UE回复的ACK消息(ack＝k+1)后，给S-AS回复ACK消息(ack＝n+1)。
应理解，UE和S-MEC之间建立MPTCP连接的过程与S502中UE和S-PSA之间建立MPTCP连接的过程类似。但需注意，S-MEC的TCP代理功能可以预配置，而不是根据SMF的指示激活的，因此S502-b类似的步骤S902-b应该是：“……由于已经根据SMF的指示激活了TCP代理功能……”，而不是S502-b中描述的“……由于S-MEC的TCP代理功能已经预配置……”。
S903，SMF向S-MEC发送DNAI变化通知。
具体地，SMF在检测到UE移动需要切换PSA的情况下，向S-MEC发送DNAI变化通知，该DNAI变化通知包括目标DNAI。
S904，S-MEC向T-MEC发送第一传输层连接的上下文。
具体地，S-MEC可以根据目标DNAI确定T-MEC，并且向T-MEC发送第一传输层连接的上下文。该上下文为UE和S-MEC之间的MPTCP连接的上下文，例如可以包括下述中的一项或多项：UE用于第一传输层连接的IP地址、端口号、MPTCP连接两端的即UE和S-MEC的Key信息、哈希加密算法信息(如采用HMAC-SHA256加密算法)、DSN和SSN之间的映射关系和ISSN等信息。
本申请可以应用于两种模式，即UL CL模式和SSC mode 3。对于UL CL模式，SMF选择T-PSA后，插入T-PSA作为UL CL；对于SSC mode 3，SMF触发UE建立一个新的PDU会话，该PDU会话以T-PSA作为用户面锚点。S905，T-MEC建立UE和T-AS之间的第二路径。
具体地，T-MEC根据第一传输层连接的上下文建立与UE之间的第三传输层连接，即MPTCP连接，使得第三传输层连接和第一传输层连接属于同一个MPTCP会话，并且，T-MEC建立与T-SA之间的第四传输层连接，即TCP连接。
UE和T-MEC之间建立MPTCP连接的过程与上文中S505中的UE和T-PSA之间建立MPTCP连接的过程类似，T-MEC和T-AS之间建立TCP连接的过程与S505中T-PSA和T-AS和之间建立TCP连接的过程类似，这里不再赘述。
在建立第三传输层连接时，T-MEC发起的TCP SYN消息中可以将MP_JOIN option的flag的最后一个bit位设置为B＝1，以指示新建子流是备选路径backup path，即此时在第一传输层连接可用的情况下，第三传输层连接作为备选路径不用来传输数据，数据还是在第一传输层连接上传输。
可选的，对于UL CL模式或SSC mode 3，UE用于第二路径或第二路径的第三传输层连接的IP地址，可以是S-MEC分配并发送给UE的，也可以是通过MEC网络配置服务器分配并发送给UE的。
S906，第三传输层连接建立完成后，T-MEC向S-MEC发送第三传输层连接建立完成消息。
S907，S-MEC收到第三传输层连接建立完成消息后，判断是否接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文。
若确定结果为是，则执行S908，否则，不执行S908以及后续步骤。
在该步骤中，S-MEC要判断是否接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文，需要先检测业务请求报文和业务应答报文。对于S-MEC开始检测业务请求报文和业务应答报文的时间，本申请不做限定。例如，S-MEC可以在收到T-MEC在 S906发送的第三传输层连接建立完成消息后开始检测业务请求报文和业务应答报文。再如，S-MEC可以在S904中向T-MEC发送第一传输层连接的上下文之后开始检测业务请求报文和业务应答报文。
示例性的，S-MEC判断是否接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文的方式与S508中S-PSA判断是否接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文的方式类似，这里不再赘述。
S908，S-MEC向UE发送第一指示信息。
该步骤与S509类似，具体可以参见上文对S509所作的说明。可以理解，S908与S509唯一不同的是，S509由S-PSA执行，S908由S-MEC执行。
S909，UE根据第一指示信息，将数据传输的路径从第一传输层连接切换至第三传输层连接。
该步骤可以参照S510，这里不再赘述。
根据本申请提供的方法，S-MEC和T-MEC可以分别和UE之间建立一条MPTCP连接，在需要进行路径切换的情况下，在S-MEC检测到针对UE发送的业务请求的完整的业务应答报文后，UE将数据传输的路径从与S-MEC之间的MPTCP连接切换至与T-MEC之间的MPTCP连接。通过该方法，可以确保在一个完整的状态交互过程完成后执行路径切换，保证应用迁移过程中应用的超低时延需求。
图9所示的方法可以应用两种模式，即SSC mode 3和UL CL模式。针对SSC mode 3模式，路径切换前后的数据传输的路径如图10所示。针对UL CL模式，路径切换前后的数据传输的路径如图11所示。
图12是一种路径切换方法的示意性流程图。在该方法，第一传输层连接、第二传输层连接、第三传输层连接和第四传输层连接都为TCP连接。如图12所示，该方法可以包括S1201至S1206，下面分别对各步骤进行说明。
S1201，UE在确定应用需要发起业务时，为该业务关联一个PDU会话。
该步骤可以参考S901，此处不再赘述。
S1202，UE和S-AS之间建立第一路径。
具体地，UE和S-MEC之间建立第一传输层连接，即TCP连接，S-MEC和S-AS之间建立第二传输层连接，即TCP连接。
S1202可以通过以下方式实现：
1、S-MEC和UE之间基于TCP的三次握手过程建立TCP连接，即S-MEC和UE之间的第一传输层连接。具体如下：
1202-a：UE发起业务时，向S-AS发送TCP SYN消息(syn＝j)，等待S-AS确认，j表示序号。
1202-b：S-MEC收到UE发送的TCP SYN消息后，代理S-AS与UE之间建立TCP连接，即代理S-AS向UE发送SYN和ACK消息(syn＝k，ack＝j+1)，其中，k表示序号。S-MEC预配置支持TCP代理功能。
1202-c：UE向S-MEC发送ACK消息(ack＝k+1)，用来确认已经收到SYN和ACK消息。S-MEC收到UE的ACK消息，完成与UE的三次握手，UE和S-MEC之间的第一传输层连接建立完成。
2、S-MEC和S-AS之间基于TCP的三次握手过程建立TCP连接，即S-MEC和S-AS之间的第二传输层连接。具体如下：
1202-d：S-MEC向S-AS发送TCP SYN消息(syn＝m)，等待S-AS确认，m表示序号；
1202-e：S-AS收到TCP SYN消息，回复SYN+ACK消息(syn＝n，ack＝m+1)，其中，n表示序号；
1202-f：S-MEC收到SYN+ACK消息，回复ACK消息(ack＝n+1)，用来确认已经收到SYN+ACK消息。
其中，在执行完1202-a后，上述步骤的执行步骤可以是：1202-b、1202-c和1202-d、1202-e、1202-f可以并行执行，即在按序执行1002-b、1002-c的同时按序执行1202-d、1202-e、1202-f；也可以是按照1202-a、1202-d、1202-e、1202-b、1202-c、1202-f的顺序执行，即S-MEC在接收到S-AS回复是SYN+ACK消息(syn＝n，ack＝m+1)后，再向UE发送SYN+ACK消息(syn＝k，ack＝j+1)，并在收到UE回复的ACK消息(ack＝k+1)后，给S-AS回复ACK消息(ack＝n+1)。
S1203，SMF向S-MEC发送DNAI变化通知。
具体地，SMF在检测到UE移动需要切换PSA的情况下，向S-MEC发送DNAI变化通知，该DNAI变化通知包括目标DNAI。S-MEC可以根据该目标DNAI确定T-MEC。
S1204，S-MEC在收到DNAI变化通知消息后，判断是否接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文。
若确定结果为是，则执行S1205，否则，不执行S1205。
在该步骤中，S-MEC要判断是否接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文，需要先检测业务请求报文和业务应答报文。对于S-MEC开始检测业务请求报文和业务应答报文的时间，本申请不做限定。例如，S-MEC可以在收到SMF在S1203发送的DNAI变化通知消息后开始检测业务请求报文和业务应答报文，本申请不做具体限定。
示例性的，S-MEC判断是否接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文的方式与S508中S-PSA判断是否接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文的方式相同，这里不再赘述。
S1205，S-MEC向T-MEC发送第一传输层连接的上下文。
该上下文包括第一传输层连接参数和传输状态参数，所述第一传输层连接参数用于所述第三传输层连接的生成，所述传输状态参数用于指示第一传输层连接的数据传输状态。其中，第一传输层连接参数可以包括UE的IP地址和/或端口号；可选的，还可以包括S-AS的IP地址和/或端口号；或者可选的，还可以包括S-PSA在第一传输层连接使用的IP地址和/或端口号。第一传输层连接的传输状态参数至少包括：第一传输层连接上上行数据已发送的TCP序号，下行数据已发送的TCP序号，上下行已发送的TCP ACK的序号。
也就是说，根据S-MEC向T-MEC发送所述上下文，可以生成第三传输层连接，第三传输层连接与第一传输层连接有相同的传输层连接参数和传输状态参数，对于UE来说，不感知第三传输层连接的生成，仍然认为在通过第一传输层传输数据。第三传输层连接生成后，T-MEC将来自UE的数据通过第四传输层连接发送给T-AS，即传输路径从第一路 径切换至第二路径。
示例性的，第一传输层连接的上下文可以由S-MEC携带在HTTP响应消息中发送给T-PSA，也可以在S-MEC判断已经接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文后，在S-MEC将业务应答报文发送后，将第一连接的上下文通过第一用户面报文发送给T-MEC，所述第一用户面报文是紧跟在所述业务应答报文之后发送的报文。
S1206，T-MEC和T-AS之间建立第四传输层连接。
具体的，第四传输层连接为TCP连接。T-MEC和T-AS之间基于TCP的三次握手过程建立TCP连接，由T-MEC发起TCP三次握手过程，具体步骤参考S505中的505-d、505-e、和505-f，本处不再赘述。
具体的，只要S1206在S1205之前执行就可以，本申请不做具体限定，示例性地，可以是T-AS上的应用向T-MEC注册完成后，T-MEC就和T-AS建立第四传输层连接。
应理解，T-MEC生成第三传输层连接并且建立第四传输层连接后，数据传输的路径就由第一路径切换至第二路径。
根据本申请提供的方法，S-MEC和UE之间建立一条TCP连接，在S-MEC检测到针对UE发送的业务请求的完整的业务应答报文后，将S-MEC上的TCP连接状态迁移到T-MEC，使得UE的传输路径可以从与S-MEC之间的TCP连接切换至与T-MEC之间的TCP连接。通过该方法，可以确保在一个完整的状态交互过程完成后执行路径切换，保证应用迁移过程中应用的超低时延需求。
图12所示的方法可以应用到UL CL模式，针对该模式，路径切换前后的数据传输的路径如图11所示。
下面以会话管理网元为SMF，源传输层代理网元为S-PSA，目标传输层代理网元为T-PSA，第一应用服务器为S-AS，第二应用服务器为T-AS为例，对申请提供的另一种路径切换方法进行说明。
图13是本申请提供的另一种路径切换方法的示意性流程图。该方法与图5所示的方法的不同之处在于，图5中由S-PSA判断是否接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文，而该方法中，由UE判断是否接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文。
如图13所示，该方法可以包括S1301至S1309，以下对各步骤进行说明。
S1301至S1306，参照S501至S506，这里不再赘述。
S1307，SMF向UE发送路径切换指示信息。
SMF根据第三传输层连接建立完成消息，获知第三传输层连接建立完成后，向UE发送路径切换指示信息，指示UE进行路径切换。
可选地，S1307也可以不执行。即，不由SMF指示UE进行路径切换，而由UE自主决定进行路径切换。比如，若第三传输层连接建立完成，则UE确定需要进行路径切换。UE判断第三传输层连接建立完成的方法，可以是UE在建立第三传输层连接时，接收到T-PSA发送的三次握手过程中的ACK消息，UE即可以判断第三传输层连接建立完成。
S1308，UE判断是否接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文。
若确定结果为是，则执行S1309，否则，不执行S1309。
示例性的，如果业务请求消息为HTTP请求(HTTP request)消息，业务应答消息为HTTP应答(HTTP response)消息，UE可以通过解析HTTP响应消息和HTTP应答消息来判断是否收到S-AS发送的针对UE发送的完整的HTTP应答消息。比如，UE可以根据HTTP应答消息中的消息状态码来判断HTTP应答消息是否是分段应答响应消息，如果HTTP应答消息携带的HTTP状态码是200，则表示HTTP应答消息没有进行分段，UE可以在收到该HTTP应答消息的时候可以判断已经收到对应的HTTP请求消息的完整的应答消息；如果HTTP应答消息携带的HTTP状态码是206，则表示S-AS通过分段响应的方式给UE发送业务报文，UE需要根据HTTP请求消息中携带的Range字段以及HTTP应答消息中的Content-Range字段来判断所接收的HTTP响应消息是不是HTTP请求消息对应的最后一个段响应消息。其中，HTTP请求消息中携带的Range字段是UE用来告知S-AS请求的内容的范围，HTTP应答消息中的Content-Range字段是S-AS用来告知响应的范围以及实际长度。
S1309，UE将数据传输的路径从第一路径切换至第二路径。
或者说，UE将数据传输的路径从第一传输层连接切换至第三传输层连接。
可选的，UE还设置在第三传输层连接发送的MPTCP报文的TCP选择，设置MP_PRIO option的flag B＝0，以指示T-PSA第三传输层连接的优先级高于第一传输层连接，通过所述第三传输层连接传输数据。
根据本申请提供的方法，S-PSA和T-PSA可以分别和UE之间建立一条MPTCP连接，在需要进行路径切换的情况下，在UE检测到针对UE发送的业务请求的完整的业务应答报文后，UE将数据传输的路径从与S-PSA之间的MPTCP连接切换至与T-PSA之间的MPTCP连接。通过该方法，可以确保在一个完整的状态交互过程完成后执行路径切换，保证应用迁移过程中应用的超低时延需求。
应理解，图13所示的方法可以应用两种模式，即SSC mode 3和UL CL模式。针对SSC mode 3模式，路径切换前后的数据传输的路径如图6所示。针对UL CL模式，路径切换前后的数据传输的路径如图7所示。
图14是本申请提供的另一种路径切换方法的示意性流程图。该方法与图13所示的方法的不同之处在于，图13源传输层代理网元为S-PSA，目标传输层代理网元为T-PSA，图14中源传输层代理网元为S-MEC，目标传输层代理网元为T-MEC。
如图14所示，该方法可以包括S1401至S1409，以下对各步骤进行说明。
S1401至S1405，参照S901至S905，这里不再赘述。
S1406，UE确定需要进行路径切换。
具体地，若第三传输层连接建立完成，则UE确定需要进行路径切换，否则不需要进行路径切换。UE判断第三传输层连接建立完成的方法，可以是UE在建立第三传输层连接时，接收到T-MEC发送的三次握手过程中的ACK消息，UE即可以判断第三传输层连接建立完成。
也可以是，SMF指示UE需要执行路径切换。具体的，SMF根据第三传输层连接建立完成消息，获知第三传输层连接建立完成后，向UE发送路径切换指示信息，指示UE进行路径切换。SMF可以是从T-MEC获知第三传输层建立完成，也可以是从AF获知第三传输层建立完成，此时AF是从T-MEC获知第三传输层建立完成。
S1407，UE判断是否接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文。
若确定结果为是，则执行S1408，否则，不执行S1408以及后续步骤。
S1407可以参照S1308，这里不再详述。
S1408，参照S1309。
根据本申请提供的方法，S-MEC和T-MEC可以分别和UE之间建立一条MPTCP连接，在需要进行路径切换的情况下，在UE检测到针对UE发送的业务请求的完整的业务应答报文后，UE将数据传输的路径从与S-MEC之间的MPTCP连接切换至与T-MEC之间的MPTCP连接。通过该方法，可以确保在一个完整的状态交互过程完成后执行路径切换，保证应用迁移过程中应用的超低时延需求。
应理解，图14所示的方法可以应用两种模式，即SSC mode 3和UL CL模式。针对SSC mode 3模式，路径切换前后的数据传输的路径如图10所示。针对UL CL模式，路径切换前后的数据传输的路径如图11所示。
下面以会话管理网元为SMF，第一应用服务器为S-AS，第二应用服务器为T-AS为例，对申请提供的又一种路径切换方法进行说明。
图15是本申请提供的又一种路径切换方法的示意性流程图。如图15所示，该方法可以包括S1501至S1508，以下对各步骤分别说明。
S1501，参照S501。
S1502，UE和S-AS之间建立第一传输层连接。
这里的第一传输层连接可以是MPTCP连接，但本申请对此不作限定。
UE和S-AS之间建立MPTCP连接的过程可以参考S502中描述的UE和S-PSA之间建立MPTCP连接的过程，这里不再详述。
S1503，S-AS向T-AS发送第一传输层连接的上下文。
比如，S-AS可以在收到MEC平台网元或应用管理网元或AF的指示时，向T-AS发送第一传输层连接的上下文。示例性的，第一传输层连接的上下文的可以包括下述中的一项或多项：UE用于第一传输层连接的IP地址、端口号、MPTCP连接两端的即UE和S-AS的Key信息、哈希加密算法信息、DSN和SSN之间的映射关系和ISSN等信息。
S1504，T-AS根据第一传输层连接的上下文，建立与UE之间的第二传输层连接。
这里的第二传输层连接可以是MPTCP连接，但本申请对此不作限定。
UE和T-AS之间建立MPTCP连接的过程可以参考S505中描述的UE和T-PSA之间建立MPTCP连接的过程，这里不再详述。
在建立第二传输层连接时，可以将MP_JOIN option的SYN flag的最后一个bit位设置为B＝1，以指示新建子流是备选路径backup path，即此时第二传输层连接作为备选路径不用来传输数据，数据还是在第一传输层连接上传输。
S1505，T-AS向SMF发送第二传输层连接建立完成消息。
具体地，T-AS在第二传输层连接建立完成后，向AF或MEC平台网元发送第二传输层连接建立完成消息，AF或MEC平台网元转发第二传输层连接建立完成消息至SMF。
S1506，SMF向UE发送路径切换指示信息。
SMF根据第二传输层连接建立完成消息，可以获知第二传输层连接建立完成，从而 可以通过向UE发送路径切换指示信息，指示UE进行路径切换。
S1507，UE判断是否接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文。
若确定结果为是，则执行S1508，否则，不执行S1508。
示例性的，如果业务请求消息为HTTP请求(HTTP request)消息，业务应答消息为HTTP应答(HTTP response)消息，UE可以通过解析HTTP响应消息和HTTP应答消息来判断是否收到S-AS发送的针对UE发送的完整的HTTP应答消息。比如，UE可以根据HTTP应答消息中的消息状态码来判断HTTP应答消息是否是分段应答响应消息，如果HTTP应答消息携带的HTTP状态码是200，则表示HTTP应答消息没有进行分段，UE可以在收到该HTTP应答消息的时候可以判断已经收到对应的HTTP请求消息的完整的应答消息；如果HTTP应答消息携带的HTTP状态码是206，则表示S-AS通过分段响应的方式给UE发送业务报文，UE需要根据HTTP请求消息中携带的Range字段以及HTTP应答消息中的Content-Range字段来判断所接收的HTTP响应消息是不是HTTP请求消息对应的最后一个段响应消息。其中，HTTP请求消息中携带的Range字段是UE用来告知S-AS请求的内容的范围，HTTP应答消息中的Content-Range字段是S-AS用来告知响应的范围以及实际长度。
S1508，UE将数据传输的路径从第一传输层连接切换至第二传输层连接。
具体地，在UE确定要进行路径切换的情况下，若接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文，则将数据传输的路径从第一传输层连接切换至第二传输层连接。
可选地，UE还设置在第二传输层连接发送的MPTCP报文的TCP选项，设置MP_PRIO option的flag B＝0，以指示T-PSA第二传输层连接的优先级高于第一传输层连接，通过所述第二传输层连接传输数据。
可选的，也可以不执行S1505和S1506，UE在和T-AS完成MPTCP三次握手过程建立了第二传输层连接后，若接收到S-AS发送的针对UE发送的业务请求的完整的业务应答报文，则UE将数据传输的路径从第一传输层连接切换到第二传输层连接。
根据本申请提供的方法，S-AS和T-AS可以分别和UE之间建立一条传输层连接，在需要进行路径切换的情况下，若UE检测到针对UE发送的业务请求的完整的业务应答报文后，UE从与S-AS之间的传输层连接切换至与T-AS之间的传输层连接。通过该方法，可以确保在一个完整的状态交互过程完成后执行路径切换，保证应用迁移过程中应用的超低时延需求。
应理解，图15所示的方法可以应用两种模式，即SSC mode 3和UL CL模式。针对SSC mode 3模式或UL CL模式，路径切换前后的数据传输的路径如图16所示。
下面以会话管理网元为SMF，第一应用服务器为S-AS，第二应用服务器为T-AS，源传输层代理网元为S-PSA，目标传输层代理网元为T-PSA为例，对图17至图20所示的路径切换方法进行说明。
图17是本申请提供的另一路径切换方法的示意性流程图。结合图17，对该方法1700进行说明。
S1701，UE在确定应用需要发起业务时，为该业务关联一个PDU会话。
该步骤与S501相同，可以参见S501。
S1702，UE和S-AS之间建立第一路径。
具体地，UE和S-PSA之间建立第一传输层连接，S-PSA和S-AS之间建立第二传输层连接，第一传输层连接和第二传输层连接都为TCP连接。
应理解，S1702与S802相同，具体可以参见上文对S802的说明。
S1703，SMF指示T-PSA建立T-PSA与T-AS之间的TCP连接，即第四传输层连接。
比如，SMF在检测到UE移动需要切换PSA的情况下，为UE选择T-PSA，并插入所选择T-PSA作为UL CL。并且，SMF可以向所选择的T-PSA发送路由信息，该路由信息指示T-PSA建立与T-AS之间的TCP连接。比如，SMF可以通过N4会话修改请求消息向T-PSA发送该路由信息。可选的，所述路由信息可以包括：T-AS的IP地址信息，该IP地址信息用于T-PSA建立与T-AS之间的传输层连接，示例性的，SMF可以通过N4会话建立请求消息或N4会话修改请求消息向T-PSA发送包括该的IP地址信息的路由信息。
S1704，T-PSA和T-AS之间建立第四传输层连接。
T-PSA可以根据SMF的指示，获取T-AS的IP地址信息，然后与T-AS之间基于TCP的三次握手过程建立TCP连接。由T-PSA发起的TCP三次握手过程，具体步骤参考S505中的505-d、505-e、和505-f，此处不再赘述。
S1705，SMF向S-PSA发送路径切换指示信息。
比如，SMF可以在确定第四传输层连接建立完成后发送路径切换指示信息。
可选地，SMF可以通过N4会话修改请求消息向S-PSA发送该路径切换指示信息。
S1706，S-PSA收到路径切换指示信息后，判断是否接收到UE发送的新的业务请求报文。
S-PSA收到路径切换指示信息，可以确定需要进行路径切换。在此情况下，S-PSA判断是否接收到UE发送的新的业务请求报文，如果确定结果为是，则执行S1707以及后续步骤。
这里，新的业务请求报文是指业务请求报文不是分段业务请求报文，或者，业务请求报文是分段业务请求报文，且是第一个分段。
应理解，一个业务请求所对应的完整的业务请求报文可以分成多段进行传输，即每次可以传输一个分段，服务器(例如本申请中S-AS或T-AS)在接收到所有分段后，进行响应；或者服务器针对每个分段进行响应，此时服务器需要根据已经收到的一个或多个分段给终端设备回复响应(例如服务器可以收到第一个分段业务请求后根据第一个分段业务请求回复响应，指示终端设备可以继续发生后学的分段请求；收到第二个业务请求后根据第一个分段业务请求和第二个分段业务请求回复响应)。终端设备接收到服务器发送的完整的响应报文后，可以发送新的业务请求报文。
可选地，该新的业务请求报文可以是HTTP请求消息，本申请对此不作限定。
S1707，S-PSA向T-PSA发送该新的业务请求报文和第一传输层连接的上下文。
第一传输层连接的上下文用于将UE和S-PSA之间的连接状态迁移至T-PSA。
示例性的，第一传输层连接的上下文可以包括第一传输层连接参数和第一传输状态参数，第一传输层连接参数用于第三传输层连接的生成，第一传输状态参数用于指示第一传输层连接的数据传输状态。
比如，第一传输层连接参数可以包括UE用于第一传输层连接的IP地址和端口号。可选的，还可以包括S-AS的IP地址和/或端口号；或者可选的，还可以包括S-PSA在第一传输层连接使用的IP地址和端口号。比如，第一传输层连接的传输状态参数可以包括下述中的一向或多项：第一传输层连接上上行数据已发送的TCP序号、下行数据已发送的TCP序号或上下行已发送的TCP ACK的序号。
示例性的，第一传输层连接的上下文可以由S-PSA携带在HTTP请求消息中发送给T-PSA，也可以在S-PSA判断已经接收UE发送的新的业务请求报文后，S-PSA将该新的业务请求报文发送给T-PSA后，将第一传输层连接的上下文通过第一用户面报文发送给T-PSA，所述第一用户面报文是紧跟在所述新的业务请求报文之后发送给T-PSA的报文。
应理解，S-PSA将第一传输层连接上下文发送给T-PSA后，S-PSA针对该业务数据流的TCP代理功能就被去激活，也就是说，针对该业务数据流的报文，S-PSA不再进行传输层的TCP协议处理。S1708，T-PSA根据第一传输层连接的上下文生成第三传输层连接。
应理解，第三传输层连接与第一传输层连接有相同的传输层连接参数和传输状态参数，对于UE来说，不感知第三传输层连接的生成，仍然认为在通过第一传输层连接传输数据。
T-PSA生成第三传输层连接后或者说S-PSA发送第一传输层连接上下文后，数据传输的路径将从第一路径切换至第二路径，即，UE发送的数据将通过第三传输层连接发送给T-PSA，T-PSA将接收到的信息通过第四传输层连接发送给T-AS。
应理解，第二路径包括第三传输层连接和第四传输层连接。
还应理解，T-PSA生成第三传输层连接也可以理解为T-PSA保存第一传输层连接的上下文。
S1709，T-PSA将该新的业务请求报文发送给T-AS。
应理解，本申请并不限定S1708和S1709的先后顺序。
还理解，后续T-AS对该新的业务请求报文的响应将通过第二路径传输。
根据本申请提供的路径切换方法，S-PSA和UE之间建立一条TCP连接，在S-PSA确定需要进行路径切换且检测到UE发送的新的业务请求报文后，可以将S-PSA上的第一传输层连接的状态迁移到T-PSA，从而可以将报文的传输路径从与S-AS之间的路径切换至与T-AS之间的路径。通过该方法，可以确保一个完整的状态交互过程在同一路径上进行，保证应用迁移过程中应用的超低时延需求。
图18是本申请提供的另一路径切换方法的示意性流程图。结合图18，对该方法1800进行说明。
S1801至S1804，和S1701至S1704相同，可以参见S1701至S1704。
S1805，SMF向S-PSA发送，指示S-PSA将TCP连接状态迁移到T-PSA。
或者说，该状态迁移指示信息指示S-PSA将S-PSA与UE之间的连接状态以及S-PSA与S-AS之间的连接状态迁移至T-PSA。
示例性的，SMF可以在检测到UE移动需要切换PSA的情况下，为UE选择目标T-PSA，并插入T-PSA作为UL CL。之后，SMF向S-PSA发送该指示信息。
可选地，SMF也可以在确定第四传输层连接建立完成后发送该指示信息。
示例性的，SMF可以通过N4会话修改请求消息向S-PSA发送该指示信息。
S1806，S-PSA收到SMF发送的指示信息后，将TCP连接状态迁移至T-PSA，即S-PSA将第一传输层连接的上下文和第二传输层连接的上下文发送给T-PSA。
示例性的，第一传输层连接的上下文可以包括第一传输层连接参数和第一传输状态参数。第一传输层连接参数用于第三传输层连接(UE和T-PSA之间的TCP连接)的生成，第一传输状态参数用于指示第一传输层连接的数据传输状态。比如，第一传输层连接参数可以包括UE用于第一传输层连接的IP地址和端口号。可选的，还可以包括S-AS的IP地址和/或端口号；或者可选的，还可以包括S-PSA在第一传输层连接使用的IP地址和端口号。比如，第一传输层连接的传输状态参数可以包括下述中的一向或多项：第一传输层连接上上行数据已发送的TCP序号、下行数据已发送的TCP序号或上下行已发送的TCP ACK的序号。
第二传输层连接的上下可以文包括第二传输层连接参数和第二传输状态参数。第二传输层连接参数用于第五传输层连接(T-PSA和S-AS之间的TCP连接)的生成，第二传输状态参数用于指示第二传输层连接的数据传输状态。比如，第二传输层连接参数可以包括：S-AS的IP地址和端口号，可选的，还可以包括UE用于第一传输层连接的IP地址和/或端口号。第二传输层连接的传输状态参数可以包括下述中的一项或多项：第二传输层连接上上行数据已发送的TCP序号、下行数据已发送的TCP序号或者上下行已发送的TCP ACK的序号。
S1807，T-PSA根据第一传输层连接的上下文生成第三传输层连接，根据第二传输层连接的上下文生成第五传输层连接。
应理解，第三传输层连接与第一传输层连接有相同的传输层连接参数和传输状态参数，对于UE来说，不感知第三传输层连接的生成，仍然认为在通过第一传输层连接传输数据。第五传输层连接与第二传输层连接有相同的传输层连接参数和传输状态参数，对于UE来说，不感知第五传输层连接的生成，仍然认为在通过第二传输层连接传输数据。
还应理解，T-PSA生成第三传输层连接也可以理解为T-PSA保存第一传输层连接的上下文。T-PSA生成第五传输层连接也可以理解为T-PSA保存第二传输层连接的上下文。
TCP连接状态迁移完成后，即第三传输层连接和第五传输层连接生成后，来自UE的报文将通过第三路径发送给S-AS，第三路径包括第三传输层连接和第五传输层连接。S-AS发送给UE的报文也通过第三路径发送给UE。
S1808，T-PSA判断是否接收到UE发送的新的业务请求报文。
若确定结果为是，则执行S1809，即通过第四传输层连接将该新的业务请求报文发送给T-AS。
否则，不执行S1809，T-PSA仍然通过第五传输层连接传输业务报文，即通过第三路径传输业务报文。
这里新的业务请求报文是指业务请求报文不是分段业务请求报文，或者，业务请求报文是分段业务请求报文，且是第一个分段。
应理解，一个业务请求所对应的完整的业务请求报文可以分成多段进行传输，即每次可以传输一个分段，服务器(例如本申请中S-AS或T-AS)在接收到所有分段后，进行响应；或者服务器针对每个分段进行响应，此时服务器需要根据已经收到的一个或多个分段给终端设备回复响应(例如服务器可以收到第一个分段业务请求后根据第一个分段业务请 求回复响应，指示终端设备可以继续发生后学的分段请求；收到第二个业务请求后根据第一个分段业务请求和第二个分段业务请求回复响应)。终端设备接收到服务器发送的完整的响应报文后，可以发送新的业务请求报文；或者终端设备可以随时发送新的业务请求报文，新的业务请求报文以及对应的响应报文、新的业务请求报文对应的后续分段报文以及分段报文对应的响应报文将通过第二路径传输，其它业务请求报文和对应的业务响应报文将通过第三路径传输。
S1809，T-PSA通过第四传输层连接向T-AS发送该新的业务请求报文。
第四传输层连接和第三传输层连接构成第二路径。
应理解，T-PSA通过第四传输层连接向T-AS发送该新的业务请求报文，也可以理解为T-PSA将数据传输的路径从第一路径切换至第二路径。
还应理解，若S1808中的判断结果为是，后续T-AS将通过第二路径向UE发送针对该新的业务请求报文的响应报文。
根据本申请提供的方法，S-PSA和UE之间建立一条TCP连接，在S-PSA确定需要进行路径切换的情况下，将S-PSA上的TCP连接状态迁移到T-PSA。并且，在T-PSA检测到UE发送的新的业务请求报文后，将该业务请求报文的传输路径从T-PSA与S-AS之间的TCP连接切换至与T-PSA与T-AS之间的TCP连接。通过该方法，可以确保一个完整的状态交互过程在同一路径上进行，保证应用迁移过程中应用的超低时延需求。
图19是本申请提供的另一路径切换方法的示意性流程图。结合图19，对该方法1900进行说明。
S1901至S1906，和S1501至S1506相同，可以参见S1501至S1506。
S1907，UE判断待发送的业务请求报文是否为新的业务请求报文。
即，UE判断待发送的业务请求报文是否满足下述中的其中一个：
该待发送的业务请求报文为分段业务请求报文，且为该待发送的业务请求报文对应的完整的业务请求报文的第一个分段；
该待发送的业务请求报文不为分段业务请求报文。
若满足，则执行S1908，否则，不执行S1908。
S1908，UE将数据传输的路径从第一传输层连接切换至第二传输层连接。
即，UE将通过第二传输层连接发送该待发送的业务请求报文。后续，T-AS和UE之间的信息将通过第二传输层连接传输。
可选地，UE还可以设置通过第二传输层连接发送的MPTCP报文的TCP选项，具体为设置MP_PRIO option的flag B＝0，以指示T-PSA第二传输层连接的优先级高于第一传输层连接。
可选的，也可以不执行S1905和S1906。比如，UE在和T-AS完成MPTCP三次握手过程建立了第二传输层连接后，若待发送的业务请求报文为新的业务请求报文，则UE将数据传输的路径从第一传输层连接切换到第二传输层连接。
根据本申请提供的方法，S-AS和T-AS可以分别和UE之间建立一条传输层连接，在需要进行路径切换的情况下，若UE确定待发送的业务请求报文为新的业务请求报文的情况下，UE从与S-AS之间的传输层连接切换至与T-AS之间的传输层连接。通过该方法，可以确保在一个完整的状态交互过程完成后执行路径切换，保证应用迁移过程中应用的超 低时延需求。应理解，图19所示的方法可以应用两种模式，即SSC mode 3和UL CL模式。针对SSC mode 3模式或UL CL模式，路径切换前后的数据传输的路径如图16所示。
图20是本申请提供的另一路径切换方法的示意性流程图。结合图20，对该方法2000进行说明。
S2001至S2007，和S1301至S1307相同，可以参见S1301至S1307。
可选地，S2007也可以不执行。即，不由SMF指示UE进行路径切换，而由UE自主决定进行路径切换。比如，若第三传输层连接建立完成，则UE确定需要进行路径切换。UE判断第三传输层连接建立完成的方法，可以是UE在建立第三传输层连接时，接收到T-PSA发送的三次握手过程中的ACK消息，UE即可以判断第三传输层连接建立完成。
S2008，UE判断待发送的业务请求报文是否为新的业务请求报文。
即，UE判断待发送的业务请求报文是否满足下述中的其中一个：
该待发送的业务请求报文为分段业务请求报文，且为该待发送的业务请求报文对应的完整的业务请求报文的第一个分段；
该待发送的业务请求报文不为分段业务请求报文。
若满足，则执行S2009，否则，不执行S2009。
S2009，UE将数据传输的路径从第一路径切换至第二路径。
或者说，UE将数据传输的路径从第一传输层连接切换至第三传输层连接。
可选的，UE还设置在第三传输层连接发送的MPTCP报文的TCP选择，设置MP_PRIO option的flag B＝0，以指示T-PSA第三传输层连接的优先级高于第一传输层连接，通过所述第三传输层连接传输数据。
根据本申请提供的方法，S-PSA和T-PSA可以分别和UE之间建立一条MPTCP连接，在需要进行路径切换的情况下，若UE确定待发送的业务请求报文为新的业务请求报文的情况下，UE从与S-AS之间的传输层连接切换至与T-AS之间的传输层连接。通过该方法，可以确保在一个完整的状态交互过程完成后执行路径切换，保证应用迁移过程中应用的超低时延需求。
应理解，图20所示的方法可以应用两种模式，即SSC mode 3和UL CL模式。针对SSC mode 3模式，路径切换前后的数据传输的路径如图6所示。针对UL CL模式，路径切换前后的数据传输的路径如图7所示。
以上，结合图4至图20详细说明了本申请实施例提供的方法。以下，结合图21至图23详细说明本申请实施例提供的装置。
图21是本申请实施例提供的通信装置的示意性框图。如图17所示，该通信装置1700可以包括收发单元3100和处理单元3200。
其中，收发单元3100可以用于接收其他装置发送的信息(或消息)，还可以用于向其他装置发送信息(或消息)。比如，发送切换指示信息或接收切换指示信息。处理单元3200可以用于进行装置的内部处理，比如将数据传输的路径从第一路径切换至第二路径。
在一种可能的设计中，该通信装置3000可对应于上述方法实施例中的源传输层代理网元(如，S-PSA，S-MEC)，如该通信装置3000可以是源传输层代理网元，也可以是源传输层代理网元中的芯片。该通信装置3000可以包括用于执行上述方法实施例中由源传输层代理网元所执行的操作的单元，并且，该通信装置3000中的各单元分别为了实现 上述方法实施例中由源传输层代理网元所执行的操作。
示例性的，处理单元3200用于，若确定需要进行路径切换，在收发单元3100接收到第一应用服务器发送的针对业务请求的完整的业务应答报文后，将数据传输的路径从第一路径切换到第二路径。其中，所述第一路径为终端设备与所述第一应用服务器之间建立的路径，所述第一路径包括第一传输层连接和第二传输层连接，所述第一传输层连接为所述通信装置3000与所述终端设备之间的传输层连接，所述第二传输层连接为所述通信装置3000与所述第一应用服务器之间的传输层连接，所述第二路径包括第三传输层连接和第四传输层连接，所述第三传输层连接为目标传输层代理网元与所述终端设备之间的传输层连接，所述第四传输层连接为所述目标传输层代理网元与第二应用服务器之间的传输层连接。
在一种可能的设计中，该通信装置3000可对应于上述方法实施例中的目标传输层代理网元(如，T-PSA，T-MEC)，如该通信装置3000可以是目标传输层代理网元，也可以是目标传输层代理网元中的芯片。该通信装置3000可以包括用于执行上述方法实施例中由目标传输层代理网元所执行的操作的单元，并且，该通信装置3000中的各单元分别为了实现上述方法实施例中由目标传输层代理网元所执行的操作。
示例性的，收发单元3100用于，接收第一传输层连接的上下文，所述第一传输层连接为源传输层代理网元与终端设备之间的传输层连接；处理单元3200用于，根据所述上下文，建立与所述终端设备之间的第三传输层连接；在完成所述第三传输层连接的建立后，收发单元3100用于，向会话管理网元或所述源传输层代理网元发送第三传输层连接建立完成消息，所述第三传输层连接建立完成消息用于指示所述第三传输层连接建立完成。
在一种可能的设计中，该通信装置3000可对应于上述方法实施例中的第一应用服务器(如，S-AS)，如该通信装置3000可以是第一应用服务器，也可以是第一应用服务器中的芯片。该通信装置3000可以包括用于执行上述方法实施例中由第一应用服务器所执行的操作的单元，并且，该通信装置3000中的各单元分别为了实现上述方法实施例中由第一应用服务器所执行的操作。
在一种可能的设计中，该通信装置3000可对应于上述方法实施例中的第二应用服务器(如，T-AS)，如该通信装置3000可以是第二应用服务器，也可以是第二应用服务器中的芯片。该通信装置3000可以包括用于执行上述方法实施例中由第二应用服务器所执行的操作的单元，并且，该通信装置3000中的各单元分别为了实现上述方法实施例中由第二应用服务器所执行的操作。
在一种可能的设计中，该通信装置3000可对应于上述方法实施例中的会话管理网元(如，SMF)，如该通信装置3000可以是会话管理网元，也可以是会话管理网元中的芯片。该通信装置3000可以包括用于执行上述方法实施例中由会话管理网元所执行的操作的单元，并且，该通信装置3000中的各单元分别为了实现上述方法实施例中由会话管理网元所执行的操作。
示例性的，收发单元3100用于，获取第一传输层连接的上下文，所述第一传输层连接为源传输层代理网元与终端设备之间的传输层连接；在所述终端设备需要更换协议数据单元PDU会话锚点的情况下，向目标传输层代理网元发送所述第一传输层连接的上下文，所述上下文用于所述目标传输层代理网元与所述终端设备之间的第三传输层连接的建立。
在一种可能的设计中，该通信装置3000可对应于上述方法实施例中的UE，如该通信装置3000可以是UE，也可以是UE中的芯片。该通信装置3000可以包括用于执行上述方法实施例中由UE所执行的操作的单元，并且，该通信装置3000中的各单元分别为了实现上述方法实施例中由UE所执行的操作。
示例性的，处理单元3200用于，当确定需要进行路径切换时，收发单元3100在接收到针对业务请求的完整的业务应答报文后，从数据传输路径从第一路径切换至第二路径。其中，所述第一路径为所述通信装置3000与第一应用服务器之间建立的路径，所述第一路径包括第一传输层连接和第二传输层连接，所述第一传输层连接为源传输层代理网元与所述通信装置3000之间的传输层连接，所述第二传输层连接为所述源传输层代理网元与所述第一应用服务器之间的传输层连接，所述第二路径包括第三传输层连接和第四传输层连接，所述第三传输层连接为目标传输层代理网元与所述通信装置3000之间的传输层连接，所述第四传输层连接为所述目标传输层代理网元与第二应用服务器之间的传输层连接。
示例性的，通信装置3000与第一应用服务器之间建立有第一传输层连接，所述通信装置3000与第二应用服务器之间建立有第二传输层连接。处理单元3200用于，当确定需要进行路径切换，收发单元3100在接收到所述第一应用服务器发送的针对业务请求的完整的业务应答报文后，将数据传输的路径从所述第一传输层连接切换至所述第二传输层连接，所述业务请求来自所述通信装置3000。
应理解，该通信装置3000为UE时，该通信装置3000中的收发单元3100可对应于图22中示出的终端设备4000中的收发器4020，该通信装置3000中的处理单元3200可对应于图22中示出的终端设备4000中的处理器4010。
还应理解，该通信装置3000为配置于UE中的芯片时，该通信装置3000中的收发单元3100可以为输入/输出接口。
应理解，该通信装置3000对应源传输层代理网元、目标传输层代理网元、第一应用服务器、第二应用服务器或会话管理网元时，该通信装置3000中的收发单元3100可对应于图23中示出的通信接口3010，处理单元3200可对应于图23中示出的处理器3020。
应理解，图21所示的装置可以用于执行上述方法实施例中任一网元所执行的操作，具体可以参见方法实施例的描述，这里不再赘述。
图22是本申请实施例提供的终端设备4000的结构示意图。该终端设备4000可应用于如图1所示的系统中，执行上述方法实施例中终端设备(或UE)的功能。如图22所示，该终端设备4000包括处理器4010和收发器4020。可选地，该终端设备4000还包括存储器4030。其中，处理器4010、收发器4002和存储器4030之间可以通过内部连接通路互相通信，传递控制或数据信号，该存储器4030用于存储计算机程序，该处理器4010用于从该存储器4030中调用并运行该计算机程序，以控制该收发器4020收发信号。可选地，终端设备4000还可以包括天线4040，用于将收发器4020输出的上行数据或上行控制信令通过无线信号发送出去。
上述处理器4010可以和存储器4030可以合成一个处理装置，处理器4010用于执行存储器4030中存储的程序代码来实现上述功能。具体实现时，该存储器4030也可以集成在处理器4010中，或者独立于处理器4010。该处理器4010可以与图21中的处理单元对 应。
上述收发器4020可以与图21中的收发单元对应。收发器4020可以包括接收器(或称接收机、接收电路)和发射器(或称发射机、发射电路)。其中，接收器用于接收信号，发射器用于发射信号。
应理解，图22所示的终端设备4000能够实现上述方法实施例中任一方法实施例中涉及终端设备的各个过程。终端设备4000中的各个模块的操作或功能，分别为了实现上述方法实施例中的相应流程。具体可参见上述方法实施例中的描述，为避免重复，此处适当省略详细描述。
上述处理器4010可以用于执行前面方法实施例中描述的由终端设备内部实现的动作，而收发器4020可以用于执行前面方法实施例中描述的终端设备向网络设备发送或从网络设备接收的动作。具体请见前面方法实施例中的描述，此处不再赘述。
可选地，上述终端设备4000还可以包括电源4050，用于给终端设备中的各种器件或电路提供电源。
除此之外，为了使得终端设备的功能更加完善，该终端设备4000还可以包括输入单元4060、显示单元4070、音频电路4080、摄像头4090和传感器4100等中的一个或多个，所述音频电路还可以包括扬声器4082、麦克风4084等。
图23图是本申请一个实施例的通信装置的示意性结构图。应理解，图23示出的通信装置5000仅是示例，本申请实施例的通信装置还可包括其他模块或单元，或者包括与图23中的各个模块的功能相似的模块，或者并非要包括图23中所有模块。
通信装置5000包括通信接口5010和至少一个处理器5020。
该通信装置5000可以对应源传输层代理网元、目标传输层代理网元、第一应用服务器、第二应用服务器以及会话管理网元中的任一网元。至少一个处理器5020执行程序指令，使得通信装置5000实现上述方法实施例中由对应网元所执行的方法的相应流程。
可选地，通信装置5000还可以包括存储器。该存储器可以存储程序指令，至少一个处理器5020可以读取存储器所存储的程序指令并执行该程序指令。
本申请实施例中的处理器可以是中央处理单元(Central Processing Unit，CPU)，该处理器还可以是其他通用处理器、数字信号处理器(digital signal processor，DSP)、专用集成电路(application specific integrated circuit，ASIC)、现成可编程门阵列(field programmable gate array，FPGA)或者其他可编程逻辑器件、分立门或者晶体管逻辑器件、分立硬件组件等。通用处理器可以是微处理器或者该处理器也可以是任何常规的处理器等。
根据本申请实施例提供的方法，本申请还提供一种计算机程序产品，该计算机程序产品包括：计算机程序代码，当该计算机程序代码在计算机上运行时，使得该计算机执行前述任一方法实施例中终端设备侧的方法。
根据本申请实施例提供的方法，本申请还提供一种计算机可读介质，该计算机可读介质存储有程序代码，当该程序代码在计算机上运行时，使得该计算机执行前述方法实施例中源传输层代理网元侧的方法。
根据本申请实施例提供的方法，本申请还提供一种计算机可读介质，该计算机可读介质存储有程序代码，当该程序代码在计算机上运行时，使得该计算机执行前述方法实施例 中目标传输层代理网元侧的方法。
根据本申请实施例提供的方法，本申请还提供一种计算机可读介质，该计算机可读介质存储有程序代码，当该程序代码在计算机上运行时，使得该计算机执行前述方法实施例中第一应用服务器侧的方法。
根据本申请实施例提供的方法，本申请还提供一种计算机可读介质，该计算机可读介质存储有程序代码，当该程序代码在计算机上运行时，使得该计算机执行前述方法实施例中第二应用服务器侧的方法。
根据本申请实施例提供的方法，本申请还提供一种计算机可读介质，该计算机可读介质存储有程序代码，当该程序代码在计算机上运行时，使得该计算机执行前述方法实施例中会话管理网元侧的方法。
根据本申请实施例提供的方法，本申请还提供一种系统，其包括上述任一方法实施例中所涉及的终端设备、源传输层代理网元、目标传输层代理网元、第一应用服务器、第二应用服务器以及会话管理网元中的至少一项。
本申请实施例还提供了一种处理装置，包括处理器和接口；所述处理器用于执行上述任一方法实施例中的方法。
应理解，上述处理装置可以是一个芯片。例如，该处理装置可以是现场可编程门阵列(field programmable gate array，FPGA)，可以是通用处理器、数字信号处理器(digital signal processor，DSP)、专用集成电路(application specific integrated circuit，ASIC)、现成可编程门阵列(field programmable gate array，FPGA)或者其他可编程逻辑器件、分立门或者晶体管逻辑器件、分立硬件组件，还可以是系统芯片(system on chip，SoC)，还可以是中央处理器(central processor unit，CPU)，还可以是网络处理器(network processor，NP)，还可以是数字信号处理电路(digital signal processor，DSP)，还可以是微控制器(micro controller unit，MCU)，还可以是可编程控制器(programmable logic device，PLD)或其他集成芯片。可以实现或者执行本申请实施例中的公开的各方法、步骤及逻辑框图。通用处理器可以是微处理器或者该处理器也可以是任何常规的处理器等。结合本申请实施例所公开的方法的步骤可以直接体现为硬件译码处理器执行完成，或者用译码处理器中的硬件及软件模块组合执行完成。软件模块可以位于随机存储器，闪存、只读存储器，可编程只读存储器或者电可擦写可编程存储器、寄存器等本领域成熟的存储介质中。该存储介质位于存储器，处理器读取存储器中的信息，结合其硬件完成上述方法的步骤。
可以理解，本申请实施例中的存储器可以是易失性存储器或非易失性存储器，或可包括易失性和非易失性存储器两者。其中，非易失性存储器可以是只读存储器(read-only memory，ROM)、可编程只读存储器(programmable ROM，PROM)、可擦除可编程只读存储器(erasable PROM，EPROM)、电可擦除可编程只读存储器(electrically EPROM，EEPROM)或闪存。易失性存储器可以是随机存取存储器(random access memory，RAM)，其用作外部高速缓存。通过示例性但不是限制性说明，许多形式的RAM可用，例如静态随机存取存储器(static RAM，SRAM)、动态随机存取存储器(dynamic RAM，DRAM)、同步动态随机存取存储器(synchronous DRAM，SDRAM)、双倍数据速率同步动态随机存取存储器(double data rate SDRAM，DDR SDRAM)、增强型同步动态随机存取存储器(enhanced SDRAM，ESDRAM)、同步连接动态随机存取存储器(synchlink DRAM， SLDRAM)和直接内存总线随机存取存储器(direct rambus RAM，DR RAM)。应注意，本文描述的系统和方法的存储器旨在包括但不限于这些和任意其它适合类型的存储器。
在上述实施例中，可以全部或部分地通过软件、硬件、固件或者其任意组合来实现。当使用软件实现时，可以全部或部分地以计算机程序产品的形式实现。所述计算机程序产品包括一个或多个计算机指令。在计算机上加载和执行所述计算机指令时，全部或部分地产生按照本申请实施例所述的流程或功能。所述计算机可以是通用计算机、专用计算机、计算机网络、或者其他可编程装置。所述计算机指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，所述计算机指令可以从一个网站站点、计算机、服务器或数据中心通过有线(例如同轴电缆、光纤、数字用户线(digital subscriber line，DSL))或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。所述计算机可读存储介质可以是计算机能够存取的任何可用介质或者是包含一个或多个可用介质集成的服务器、数据中心等数据存储设备。所述可用介质可以是磁性介质(例如，软盘、硬盘、磁带)、光介质(例如，高密度数字视频光盘(digital video disc，DVD))、或者半导体介质(例如，固态硬盘(solid state disc，SSD))等。
上述各个装置实施例中网络设备与终端设备和方法实施例中的网络设备或终端设备完全对应，由相应的模块或单元执行相应的步骤，例如通信单元(收发器)执行方法实施例中接收或发送的步骤，除发送、接收外的其它步骤可以由处理单元(处理器)执行。具体单元的功能可以参考相应的方法实施例。其中，处理器可以为一个或多个。
在本说明书中使用的术语“部件”、“模块”、“系统”等用于表示计算机相关的实体、硬件、固件、硬件和软件的组合、软件、或执行中的软件。例如，部件可以是但不限于，在处理器上运行的进程、处理器、对象、可执行文件、执行线程、程序或计算机。通过图示，在计算设备上运行的应用和计算设备都可以是部件。一个或多个部件可驻留在进程或执行线程中，部件可位于一个计算机上或分布在2个或更多个计算机之间。此外，这些部件可从在上面存储有各种数据结构的各种计算机可读介质执行。部件可例如根据具有一个或多个数据分组(例如来自与本地系统、分布式系统或网络间的另一部件交互的二个部件的数据，例如通过信号与其它系统交互的互联网)的信号通过本地或远程进程来通信。
应理解，说明书通篇中提到的“实施例”意味着与实施例有关的特定特征、结构或特性包括在本申请的至少一个实施例中。因此，在整个说明书各个实施例未必一定指相同的实施例。此外，这些特定的特征、结构或特性可以任意适合的方式结合在一个或多个实施例中。
应理解，在本申请实施例中，编号“第一”、“第二”…仅仅为了区分不同的对象，比如为了区分不同的网络设备，并不对本申请实施例的范围构成限制，本申请实施例并不限于此。
还应理解，在本申请中，“当…时”、“若”以及“如果”均指在某种客观情况下网元会做出相应的处理，并非是限定时间，且也不要求网元实现时一定要有判断的动作，也不意味着存在其它限定。
还应理解，在本申请各实施例中，“A对应的B”表示B与A相关联，根据A可以确定B。但还应理解，根据A确定B并不意味着仅仅根据A确定B，还可以根据A和/或其 它信息确定B。
还应理解，本文中术语“和/或”，仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，本文中字符“/”，一般表示前后关联对象是一种“或”的关系。
本申请中出现的类似于“项目包括如下中的一项或多项：A，B，以及C”表述的含义，如无特别说明，通常是指该项目可以为如下中任一个：A；B；C；A和B；A和C；B和C；A，B和C；A和A；A，A和A；A，A和B；A，A和C，A，B和B；A，C和C；B和B，B，B和B，B，B和C，C和C；C，C和C，以及其他A，B和C的组合。以上是以A，B和C共3个元素进行举例来说明该项目的可选用条目，当表达为“项目包括如下中至少一种：A，B，……，以及X”时，即表达中具有更多元素时，那么该项目可以适用的条目也可以按照前述规则获得。
可以理解的，本申请实施例中，终端设备和/或网络设备可以执行本申请实施例中的部分或全部步骤，这些步骤或操作仅是示例，本申请实施例还可以执行其它操作或者各种操作的变形。此外，各个步骤可以按照本申请实施例呈现的不同的顺序来执行，并且有可能并非要执行本申请实施例中的全部操作。
本领域普通技术人员可以意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，能够以电子硬件、或者计算机软件和电子硬件的结合来实现。这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
所属领域的技术人员可以清楚地了解到，为描述的方便和简洁，上述描述的系统、装置和单元的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。
在本申请所提供的几个实施例中，应该理解到，所揭露的系统、装置和方法，可以通过其它的方式实现。例如，以上所描述的装置实施例仅仅是示意性的，例如，所述单元的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个单元或组件可以结合或者可以集成到另一个系统，或一些特征可以忽略，或不执行。另一点，所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口，装置或单元的间接耦合或通信连接，可以是电性，机械或其它的形式。
所述作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
另外，在本申请各个实施例中的各功能单元可以集成在一个处理单元中，也可以是各个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中。
所述功能如果以软件功能单元的形式实现并作为独立的产品销售或使用时，可以存储在一个计算机可读取存储介质中。基于这样的理解，本申请的技术方案本质上或者说对现有技术做出贡献的部分或者该技术方案的部分可以以软件产品的形式体现出来，该计算机软件产品存储在一个存储介质中，包括若干指令用以使得一台计算机设备(可以是个人计算机，服务器，或者网络设备等)执行本申请各个实施例所述方法的全部或部分步骤。而前述的存储介质包括：U盘、移动硬盘、只读存储器ROM、随机存取存储器RAM、磁碟 或者光盘等各种可以存储程序代码的介质。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (58)

  1. 一种路径切换方法，其特征在于，包括：
    若源传输层代理网元确定需要进行路径切换，所述源传输层代理网元在接收到第一应用服务器发送的针对业务请求的完整的业务应答报文后，将数据传输的路径从第一路径切换到第二路径，
    其中，所述第一路径为终端设备与所述第一应用服务器之间建立的路径，所述第一路径包括第一传输层连接和第二传输层连接，所述第一传输层连接为所述源传输层代理网元与所述终端设备之间的传输层连接，所述第二传输层连接为所述源传输层代理网元与所述第一应用服务器之间的传输层连接，所述第二路径包括第三传输层连接和第四传输层连接，所述第三传输层连接为目标传输层代理网元与所述终端设备之间的传输层连接，所述第四传输层连接为所述目标传输层代理网元与第二应用服务器之间的传输层连接。
  2. 如权利要求1所述的方法，其特征在于，所述将数据传输的路径从所述第一路径切换到第二路径，包括：
    所述源传输层代理网元指示所述终端设备将所述数据传输的路径从所述第一传输层连接切换至所述第三传输层连接，所述第一传输层连接和所述第三传输层连接为多径传输控制协议MPTCP连接，所述第一传输层连接和所述第三传输层连接属于同一个MPTCP会话。
  3. 如权利要求1或2所述的方法，其特征在于，所述方法还包括：
    所述源传输层代理网元向所述目标传输层代理网元发送所述第一传输层连接的上下文，所述上下文用于所述第三传输层连接的建立。
  4. 如权利要求1所述的方法，其特征在于，所述将数据传输的路径从所述第一路径切换到第二路径，包括：
    所述源传输层代理网元向所述目标传输层代理网元发送所述第一传输层连接的上下文，所述上下文包括第一传输层连接参数和传输状态参数，所述第一传输层连接参数用于所述第三传输层连接的生成，所述传输状态参数用于指示所述第一传输层连接的数据传输状态。
  5. 如权利要求2所述的方法，其特征在于，所述源传输层代理网元指示所述终端设备将所述数据传输的路径从所述第一传输层连接切换至所述第三传输层连接，包括：
    所述源传输层代理网元调整所述第一传输层连接的优先级，使所述第三传输层连接的优先级高于所述第一传输层连接的优先级。
  6. 如权利要求3所述的方法，其特征在在于，所述源传输层代理网元向目标传输层代理网元发送所述第一传输层连接的上下文，包括：
    所述源传输层代理网元通过向会话管理网元发送所述上下文，向所述目标传输层代理网元发送所述上下文。
  7. 如权利要求1-6中任一项所述的方法，其特征在于，所述源传输层代理网元确定需要进行路径切换，包括：
    所述源传输层代理网元接收到所述会话管理网元发送的路径切换指示消息。
  8. 如权利要求1或2所述的方法，其特征在于，所述源传输层代理网元确定需要进行路径切换，包括：
    所述源传输层代理网元接收到第三传输层连接建立完成消息，所述第三传输层连接建立完成消息用于指示所述第三传输层连接建立完成。
  9. 如权利要求1-8中任一项所述的方法，其特征在于，所述源传输层代理网元和所述目标传输层代理网元均为用户面网元，或者，所述源传输层代理网元和所述目标传输层代理网元均为移动边缘计算MEC平台网元。
  10. 如权利要求3所述的方法，其特征在于，所述源传输层代理网元和所述目标传输层代理网元均为移动边缘计算MEC平台网元；
    以及，在所述源传输层代理网元向目标传输层代理网元发送所述第一传输层连接的上下文之前，所述方法还包括：
    所述源传输层代理网元接收会话管理网元发送的数据网络接入标识DNAI变化通知，所述DNAI变化通知包括目标DNAI；
    所述源传输层代理网元根据所述目标DNAI，确定所述目标传输层代理网元。
  11. 如权利要求1-10中任一项所述的方法，其特征在于，所述上下文包括下述中的一些或多项：
    所述终端设备用于所述第一传输层连接的IP地址和端口号、所述第一传输层连接使用的哈希加密算法信息、密钥信息、数据序列号DSN和子流序列号SSN的映射关系、初始子流序列号ISSN。
  12. 如权利要求1-11中任一项所述的方法，其特征在于，所述第一应用服务器和所述第二应用服务器提供相同的应用服务。
  13. 一种路径切换方法，其特征在于，包括：
    目标传输层代理网元接收第一传输层连接的上下文，所述第一传输层连接为源传输层代理网元与终端设备之间的传输层连接；
    所述目标传输层代理网元根据所述上下文，建立与所述终端设备之间的第三传输层连接；
    在完成所述第三传输层连接的建立后，所述目标传输层代理网元向会话管理网元或所述源传输层代理网元发送第三传输层连接建立完成消息，所述第三传输层连接建立完成消息用于指示所述第三传输层连接建立完成。
  14. 如权利要求13所述的方法，其特征在于，所述源传输层代理网元和所述目标传输层代理网元均为用户面网元，或者，所述源传输层代理网元和所述目标传输层代理网元均为移动边缘计算MEC平台网元。
  15. 一种路径切换方法，其特征在于，包括：
    会话管理网元获取第一传输层连接的上下文，所述第一传输层连接为源传输层代理网元与终端设备之间的传输层连接；
    在所述终端设备需要更换协议数据单元PDU会话锚点的情况下，所述会话管理网元向目标传输层代理网元发送所述第一传输层连接的上下文，所述上下文用于所述目标传输层代理网元与所述终端设备之间的第三传输层连接的建立。
  16. 如权利要求15所述的方法，其特征在于，所述方法还包括：
    在确定所述第三传输层连接建立完成的情况下，所述会话管理网元向所述源传输层代理网元发送路径切换指示信息，所述路径切换指示信息用于指示所述源传输层代理网元将数据传输的路径从所述第一传输层连接切换至所述第三传输层连接。
  17. 如权利要求16所述的方法，其特征在于，所述路径切换指示信息具体用于指示所述源传输层代理网元修改所述第一传输层连接的优先级，以使所述第三传输层连接的优先级大于所述第一传输层连接的优先级。
  18. 如权利要求15-17中任一项所述的方法，其特征在于，所述第一传输层连接和所述第三传输层连接为多径传输控制协议MPTCP连接，所述第一传输层连接和所述第三传输层连接属于同一个MPTCP会话。
  19. 如权利要求15-18中任一项所述的方法，其特征在于，所述源传输层代理网元和所述目标传输层代理网元均为用户面网元。
  20. 一种路径切换方法，其特征在于，包括：
    当终端设备确定需要进行路径切换时，所述终端设备在接收到针对业务请求的完整的业务应答报文后，将数据传输路径从第一路径切换至第二路径，
    其中，所述第一路径为所述终端设备与第一应用服务器之间建立的路径，所述第一路径包括第一传输层连接和第二传输层连接，所述第一传输层连接为源传输层代理网元与所述终端设备之间的传输层连接，所述第二传输层连接为所述源传输层代理网元与所述第一应用服务器之间的传输层连接，所述第二路径包括第三传输层连接和第四传输层连接，所述第三传输层连接为目标传输层代理网元与所述终端设备之间的传输层连接，所述第四传输层连接为所述目标传输层代理网元与第二应用服务器之间的传输层连接。
  21. 如权利要求20所述的方法，其特征在于，所述业务应答报文为所述终端设备从所述源传输层代理网元接收的，且所述业务应答报文指示所述第三传输层连接的优先级高于所述第一传输层连接的优先级。
  22. 如权利要求20或21所述的方法，其特征在于，所述终端设备确定需要进行路径切换，包括：
    所述终端设备接收到所述目标传输层代理网元发送的所述第三传输层连接建立完成消息，所述第三传输层连接建立完成消息用于指示所述第三传输层连接建立完成；或者，
    所述终端设备接收到会话管理网元发送的路径切换指示信息。
  23. 如权利要求20-22中任一项所述的方法，其特征在于，所述第一传输层连接和所述第三传输层连接为多径传输控制协议MPTCP连接，所述第一传输层连接和所述第三传输层连接属于同一个MPTCP会话。
  24. 如权利要求20-23中任一项所述的方法，其特征在于，所述源传输层代理网元和所述目标传输层代理网元均为用户面网元，或者，所述源传输层代理网元和所述目标传输层代理网元均为移动边缘计算MEC平台网元。
  25. 如权利要求20-24中任一项所述的方法，其特征在于，所述第一应用服务器和所述第二应用服务器提供相同的应用服务。
  26. 一种路径切换方法，其特征在于，终端设备与第一应用服务器之间建立有第一传输层连接，所述终端设备与第二应用服务器之间建立有第二传输层连接，所述方法包括：
    当所述终端设备确定需要进行路径切换，在接收到所述第一应用服务器发送的针对业 务请求的完整的业务应答报文后，将数据传输的路径从所述第一传输层连接切换至所述第二传输层连接，所述业务请求来自所述终端设备。
  27. 如权利要求26所述的方法，其特征在于，所述终端设备确定需要进行路径切换，包括：
    所述终端设备接收到会话管理网元发送的路径切换指示信息。
  28. 如权利要求26或27所述的方法，其特征在于，所述第一传输层连接和所述第二传输层连接为多径传输控制协议MPTCP连接，所述第一传输层连接和所述第三传输层连接属于同一个MPTCP会话上。
  29. 如权利要求26-28中任一项所述的方法，其特征在于，所述第一应用服务器和所述第二应用服务器提供相同的应用服务。
  30. 一种通信系统，其特征在于，包括源传输层代理网元、目标传输层代理网元和会话管理网元，其特征在于，包括：
    所述源传输层代理网元用于，向所述会话管理网元发送第一传输层连接的上下文，所述第一传输层连接为所述源传输层代理网元和终端设备之间的传输层连接；
    所述会话管理网元用于，向所述目标传输层代理网元发送所述第一传输层连接的上下文，所述第一传输层连接的上下文用于第三传输层连接的建立，所述第三传输层连接为所述目标传输层代理网元和所述终端设备之间的传输层连接；
    所述源传输层代理网元还用于，在所述第三传输层连接建立完成后，所述目标传输层代理网元还用于，在接收到针对业务请求的完整的业务应答报文后，将数据传输的路径从所述第一传输层连接切换到所述第三传输层连接。
  31. 如权利要求30所述的系统，其特征在于，所述系统还包括终端设备；
    其中，所述数据传输的路径从所述第一传输层连接切换到所述第三传输层连接，包括：
    所述源传输层代理网元指示所述终端设备将所述数据传输的路径从所述第一传输层连接切换至所述第三传输层连接，所述第一传输层连接和所述第三传输层连接为多径传输控制协议MPTCP连接，所述第一传输层连接和所述第三传输层连接属于同一个MPTCP会话；
    所述终端设备用于，根据所述源传输层代理网元的指示，将所述数据传输的路径从所述第一传输层连接切换至所述第三传输层连接。
  32. 一种路径切换方法，其特征在于，包括：
    在源传输层代理网元确定需要进行路径切换的情况下，若所述源传输层代理网元接收到终端设备发送的新的业务请求报文，所述源传输层代理网元向目标传输层代理网元发送所述新的业务请求报文和第一传输层连接的上下文，所述第一传输层连接的上下文用于所述目标传输层代理网元建立第三传输层连接，所述第三传输层连接为所述目标传输层代理网元和所述终端设备之间的传输层连接，
    其中，所述第一传输层连接为所述终端设备与所述源传输层代理网元之间的传输层连接。
  33. 如权利要求32所述的方法，其特征在于，所述第一传输层连接的上下文包括第一传输层连接参数和第一传输状态参数，所述第一传输层连接参数用于所述第三传输层连接的生成，所述第一传输状态参数用于指示所述第一传输层连接的数据传输状态。
  34. 如权利要求32或33所述的方法，其特征在于，所述源传输层代理网元确定需要进行路径切换，包括：
    所述源传输层代理网元接收到会话管理网元发送的路径切换指示消息。
  35. 一种路径切换方法，其特征在于，包括：
    目标传输层代理网元接收源传输层代理网元发送的新的业务请求报文和第一传输层连接的上下文；
    所述目标传输层代理网元通过第四传输层连接，向第二应用服务器发送所述新的业务请求报文，其中，所述第四传输层连接为所述目标传输层代理网元与所述第二应用服务器之间的传输层连接；
    所述目标传输层代理网元根据所述第一传输层连接的上下文，建立与终端设备之间的第三传输层连接，所述第一传输层连接为所述终端设备与所述源传输层代理网元之间的传输层连接；
    所述目标传输层代理网元接收所述终端设备通过所述第三传输层连接发送的报文，并通过所述第四传输层连接发送给所述第二应用服务器。
  36. 如权利要求35所述的方法，其特征在于，在所述目标传输层代理网元通过第四传输层连接，向第二应用服务器发送所述新的业务请求报文之前，所述方法还包括：
    所述目标传输层代理网元接收会话管理网元发送的第二应用服务器的IP地址信息，并根据所述IP地址信息建立所述第四传输层连接。
  37. 如权利要求35或36所述的方法，其特征在于，所述第一传输层连接的上下文包括第一传输层连接参数和第一传输状态参数，所述第一传输层连接参数用于所述第三传输层连接的生成，所述第一传输状态参数用于指示所述第一传输层连接的数据传输状态。
  38. 一种路径切换方法，其特征在于，包括：
    目标传输层代理网元接收源传输层代理网元发送的第一传输层连接的上下文和第二传输层连接的上下文，所述第一传输层连接为所述源传输层代理网元与终端设备之间的传输层连接，所述第二传输层连接为所述源传输层代理网元与第一应用服务器之间的传输层连接；
    所述目标传输层代理网元根据所述第一传输层连接的上下文，生成第三传输层连接，并根据所述第二传输层连接的上下文，生成第五传输层连接，所述第三传输层连接为所述目标传输层代理网元与所述终端设备之间的传输层连接，所述第五传输层连接为所述目标传输层代理网元与所述第一应用服务器之间的传输层连接；
    若所述目标传输层代理网元通过所述第三传输层连接接收到所述终端设备发送的新的业务请求报文，所述目标传输层代理网元将数据传输的路径从第一路径切换到第二路径，其中，所述第一路径为所述终端设备与所述第一应用服务器之间建立的路径，所述第一路径包括所述第三传输层连接和所述第五传输层连接，所述第二路径包括所述第三传输层连接和第四传输层连接，所述第四传输层连接为所述目标传输层代理网元与第二应用服务器之间的传输层连接。
  39. 如权利要求38所述的方法，其特征在于，在所述目标传输层代理网元将数据传输的路径从第一路径切换到第二路径之前，所述方法还包括：
    所述目标传输层代理网元从会话管理网元获取所述第二应用服务器的IP地址信息， 并根据所述IP地址信息建立所述第四传输层连接。
  40. 如权利要求38或39所述的方法，其特征在于，所述第一传输层连接的上下文包括所述第一传输层连接参数和第一传输状态参数，所述第一传输层连接参数用于所述第三传输层连接的生成，所述第一传输状态参数用于指示所述第一传输层连接的数据传输状态；
    所述第二传输层连接的上下文包括所述第二传输层连接参数和第二传输状态参数，所述第二传输层连接参数用于所述第五传输层连接的生成，所述第二传输状态参数用于指示所述第二传输层连接的数据传输状态。
  41. 一种路径切换方法，其特征在于，包括：
    源传输层代理网元接收会话管理网元发送的状态迁移指示信息；
    所述源传输层代理网元根据所述状态迁移指示信息，向目标传输层代理网元发送第一传输层连接的上下文和第二传输层连接的上下文，其中，所述第一传输层连接为所述源传输层代理网元与终端设备之间的传输层连接，所述第二传输层连接为所述源传输层代理网元与第一应用服务器之间的传输层连接，所述第一传输层连接的上下文用于所述目标传输层代理网元生成第三传输层连接，所述第二传输层连接的上下文用于所述目标传输层代理网元生成第五传输层连接，所述第三传输层连接为所述目标传输层代理网元与所述终端设备之间的传输层连接，所述第五传输层连接为所述目标传输层代理网元与所述第一应用服务器之间的传输层连接。
  42. 如权利要求41所述的方法，其特征在于，所述第一传输层连接的上下文包括所述第一传输层连接参数和第一传输状态参数，所述第一传输层连接参数用于所述第三传输层连接的生成，所述第一传输状态参数用于指示所述第一传输层连接的数据传输状态；
    所述第二传输层连接的上下文包括所述第二传输层连接参数和第二传输状态参数，所述第二传输层连接参数用于所述第五传输层连接的生成，所述第二传输状态参数用于指示所述第二传输层连接的数据传输状态。
  43. 一种路径切换方法，其特征在于，包括：
    在终端设备确定需要进行路径切换的情况下，若待发送的业务请求报文为新的业务请求报文，所述终端设备将数据传输路径从第一传输层连接切换至第二传输层连接，
    其中，所述第一传输层连接为所述终端设备与第一应用服务器之间的传输层连接，所述第二传输层连接为所述终端设备与所述第二应用服务器之间的传输层连接。
  44. 如权利要求43所述的方法，其特征在于，所述终端设备确定需要进行路径切换，包括：
    所述终端设备接收到会话管理网元发送的路径切换指示信息；或者，
    所述终端设备确定所述第二传输层连接建立完成。
  45. 如权利要求43或44所述的方法，其特征在于，所述第一传输层连接和所述第二传输层连接为多径传输控制协议MPTCP连接，所述第一传输层连接和所述第三传输层连接属于同一个MPTCP会话。
  46. 如权利要求43-45中任一项所述的方法，其特征在于，所述第一应用服务器和所述第二应用服务器提供相同的应用服务。
  47. 一种路径切换方法，其特征在于，包括：
    在终端设备确定需要进行路径切换的情况下，若待发送的业务请求报文为新的业务请求报文，所述终端设备将从数据传输路径从第一路径切换至第二路径，
    其中，所述第一路径为所述终端设备与第一应用服务器之间建立的路径，所述第一路径包括第一传输层连接和第二传输层连接，所述第一传输层连接为源传输层代理网元与所述终端设备之间的传输层连接，所述第二传输层连接为所述源传输层代理网元与所述第一应用服务器之间的传输层连接，所述第二路径包括第三传输层连接和第四传输层连接，所述第三传输层连接为目标传输层代理网元与所述终端设备之间的传输层连接，所述第四传输层连接为所述目标传输层代理网元与第二应用服务器之间的传输层连接。
  48. 如权利要求47所述的方法，其特征在于，所述终端设备确定需要进行路径切换，包括：
    所述终端设备接收到所述目标传输层代理网元发送的所述第三传输层连接建立完成消息，所述第三传输层连接建立完成消息用于指示所述第三传输层连接建立完成；或者，
    所述终端设备接收到会话管理网元发送的路径切换指示信息。
  49. 如权利要求47或48所述的方法，其特征在于，所述第一传输层连接和所述第三传输层连接为多径传输控制协议MPTCP连接，所述第一传输层连接和所述第三传输层连接属于同一个MPTCP会话。
  50. 如权利要求47-49中任一项所述的方法，其特征在于，所述源传输层代理网元和所述目标传输层代理网元均为用户面网元，或者，所述源传输层代理网元和所述目标传输层代理网元均为移动边缘计算MEC平台网元。
  51. 如权利要求47-50中任一项所述的方法，其特征在于，所述第一应用服务器和所述第二应用服务器提供相同的应用服务。
  52. 一种路径切换方法，其特征在于，包括：
    在源传输层代理网元确定需要进行路径切换的情况下，若所述源传输层代理网元接收到终端设备发送的新的业务请求报文，所述源传输层代理网元向目标传输层代理网元发送所述新的业务请求报文和第一传输层连接的上下文，所述第一传输层连接的上下文用于所述目标传输层代理网元建立第三传输层连接，所述第三传输层连接为所述目标传输层代理网元和所述终端设备之间的传输层连接，其中，所述第一传输层连接为所述终端设备与所述源传输层代理网元之间的传输层连接；
    所述目标传输层代理网元通过第四传输层连接，向第二应用服务器发送所述新的业务请求报文，其中，所述第四传输层连接为所述目标传输层代理网元与所述第二应用服务器之间的传输层连接；
    所述目标传输层代理网元根据所述第一传输层连接的上下文，建立所述第三传输层连接；
    所述目标传输层代理网元接收所述终端设备通过所述第三传输层连接发送的报文，并通过所述第四传输层连接发送给所述第二应用服务器。
  53. 一种通信系统，其特征在于，包括源传输层代理网元和目标传输层代理网元；
    所述源传输层代理网元用于，在确定需要进行路径切换的情况下，若接收到终端设备发送的新的业务请求报文，向所述目标传输层代理网元发送所述新的业务请求报文和第一传输层连接的上下文，所述第一传输层连接的上下文用于所述目标传输层代理网元建立第 三传输层连接，所述第三传输层连接为所述目标传输层代理网元和所述终端设备之间的传输层连接，其中，所述第一传输层连接为所述终端设备与所述源传输层代理网元之间的传输层连接；
    所述目标传输层代理网元用于，通过第四传输层连接，向第二应用服务器发送所述新的业务请求报文，其中，所述第四传输层连接为所述目标传输层代理网元与所述第二应用服务器之间的传输层连接；
    所述目标传输层代理网元还用于，根据所述第一传输层连接的上下文，建立所述第三传输层连接；
    所述目标传输层代理网元还用于，接收所述终端设备通过所述第三传输层连接发送的报文，并通过所述第四传输层连接发送给所述第二应用服务器。
  54. 一种路径切换方法，其特征在于，包括：
    源传输层代理网元接收会话管理网元发送的；
    所述源传输层代理网元根据所述状态迁移指示信息，向目标传输层代理网元发送第一传输层连接的上下文和第二传输层连接的上下文，其中，所述第一传输层连接为所述源传输层代理网元与终端设备之间的传输层连接，所述第二传输层连接为所述源传输层代理网元与第一应用服务器之间的传输层连接，所述第一传输层连接的上下文用于所述目标传输层代理网元生成第三传输层连接，所述第二传输层连接的上下文用于所述目标传输层代理网元生成第五传输层连接，所述第三传输层连接为所述目标传输层代理网元与所述终端设备之间的传输层连接，所述第五传输层连接为所述目标传输层代理网元与所述第一应用服务器之间的传输层连接；
    所述目标传输层代理网元根据所述第一传输层连接的上下文，生成所述第三传输层连接，并根据所述第二传输层连接的上下文，生成所述第五传输层连接；
    若所述目标传输层代理网元通过所述第三传输层连接接收到所述终端设备发送的新的业务请求报文，所述目标传输层代理网元将数据传输的路径从第一路径切换到第二路径，其中，所述第一路径为所述终端设备与所述第一应用服务器之间建立的路径，所述第一路径包括所述第三传输层连接和所述第五传输层连接，所述第二路径包括所述第三传输层连接和第四传输层连接，所述第四传输层连接为所述目标传输层代理网元与第二应用服务器之间的传输层连接。
  55. 一种通信系统，其特征在于，包括：源传输层代理网元和目标传输层代理网元；
    所述源传输层代理网元用于，接收会话管理网元发送的；
    所述源传输层代理网元还用于，根据所述状态迁移指示信息，向目标传输层代理网元发送第一传输层连接的上下文和第二传输层连接的上下文，其中，所述第一传输层连接为所述源传输层代理网元与终端设备之间的传输层连接，所述第二传输层连接为所述源传输层代理网元与第一应用服务器之间的传输层连接，所述第一传输层连接的上下文用于所述目标传输层代理网元生成第三传输层连接，所述第二传输层连接的上下文用于所述目标传输层代理网元生成第五传输层连接，所述第三传输层连接为所述目标传输层代理网元与所述终端设备之间的传输层连接，所述第五传输层连接为所述目标传输层代理网元与所述第一应用服务器之间的传输层连接。
    所述目标传输层代理网元用于，根据所述第一传输层连接的上下文，生成所述第三传 输层连接，并根据所述第二传输层连接的上下文，生成所述第五传输层连接；
    所述目标传输层代理网元还用于，若通过所述第三传输层连接接收到所述终端设备发送的新的业务请求报文，将数据传输的路径从第一路径切换到第二路径，其中，所述第一路径为所述终端设备与所述第一应用服务器之间建立的路径，所述第一路径包括所述第三传输层连接和所述第五传输层连接，所述第二路径包括所述第三传输层连接和第四传输层连接，所述第四传输层连接为所述目标传输层代理网元与第二应用服务器之间的传输层连接。
  56. 一种通信装置，其特征在于，所述装置用于执行如权利要求1-12中任一项、13或14、15-19中任一项、20-25中任一项、26-29中任一项、32-34中任一项、35-37中任一项、38-40中任一项、41或42、43-46中任一项、或者47-51中任一项所述的方法。
  57. 一种装置，其特征在于，包括：处理器，所述处理器与存储器耦合，所述存储器用于存储程序或指令，当所述程序或指令被所述处理器执行时，使得所述装置执行如权利要求1-12中任一项、13或14、15-19中任一项、20-25中任一项、26-29中任一项、32-34中任一项、35-37中任一项、38-40中任一项、41或42、43-46中任一项、或者47-51中任一项所述的方法。
  58. 一种可读存储介质，其上存储有计算机程序或指令，其特征在于，所述计算机程序或指令被执行时使得计算机执行如权利要求1至51中任一项所述的方法。
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