WO2021223646A1 - 保护倒换方法及装置 - Google Patents

保护倒换方法及装置 Download PDF

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Publication number
WO2021223646A1
WO2021223646A1 PCT/CN2021/090679 CN2021090679W WO2021223646A1 WO 2021223646 A1 WO2021223646 A1 WO 2021223646A1 CN 2021090679 W CN2021090679 W CN 2021090679W WO 2021223646 A1 WO2021223646 A1 WO 2021223646A1
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WIPO (PCT)
Prior art keywords
transmission path
data transmission
network device
address
bfd
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PCT/CN2021/090679
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English (en)
French (fr)
Inventor
梁波
黄蕾
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华为技术有限公司
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Priority to EP21799468.0A priority Critical patent/EP4135286A4/en
Publication of WO2021223646A1 publication Critical patent/WO2021223646A1/zh

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    • 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
    • H04L67/00—Network arrangements or protocols for supporting network services or applications
    • H04L67/14—Session management
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/46—Interconnection of networks
    • H04L12/4641—Virtual LANs, VLANs, e.g. virtual private networks [VPN]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/46—Interconnection of networks
    • H04L12/4641—Virtual LANs, VLANs, e.g. virtual private networks [VPN]
    • H04L12/4675—Dynamic sharing of VLAN information amongst network nodes
    • 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
    • H04L45/28—Routing or path finding of packets in data switching networks using route fault recovery
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L61/00—Network arrangements, protocols or services for addressing or naming
    • H04L61/09—Mapping addresses
    • H04L61/10—Mapping addresses of different types
    • H04L61/103—Mapping addresses of different types across network layers, e.g. resolution of network layer into physical layer addresses or address resolution protocol [ARP]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L61/00—Network arrangements, protocols or services for addressing or naming
    • H04L61/09—Mapping addresses
    • H04L61/25—Mapping addresses of the same type
    • H04L61/2503—Translation of Internet protocol [IP] addresses
    • 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
    • H04L67/00—Network arrangements or protocols for supporting network services or applications
    • H04L67/14—Session management
    • H04L67/141—Setup of application sessions
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L67/00—Network arrangements or protocols for supporting network services or applications
    • H04L67/14—Session management
    • H04L67/148—Migration or transfer of sessions
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/40—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L2101/00—Indexing scheme associated with group H04L61/00
    • H04L2101/60—Types of network addresses
    • H04L2101/618—Details of network addresses
    • H04L2101/622—Layer-2 addresses, e.g. medium access control [MAC] addresses

Definitions

  • This application relates to the field of communications, and in particular to a protection switching method and device.
  • a data transmission path group can usually be configured for a certain business.
  • the service flow can be switched to another data transmission path for transmission. In this way, the continuity of the business can be ensured.
  • the network device working at the data link layer is also called a layer 2 device.
  • the layer 2 device can forward the received data according to the media access control (MAC) address included in the data packet it receives.
  • Packet; a network device that works at the network layer can also be referred to as a three-layer device.
  • the three-layer device can forward the received data packet according to the Internet Protocol (IP) address included in the received data packet. That is to say, the second-tier device and the third-tier device use different communication protocols to forward the received data packets.
  • IP Internet Protocol
  • layer 2 devices and layer 3 devices use different methods to detect faults on data transmission paths, and layer 2 devices and layer 3 devices cannot coordinate protection switching.
  • the embodiments of the present application provide a protection switching method and device.
  • Layer 2 devices and Layer 3 devices can perform protection switching in coordination, which is beneficial to the MAC switching domain and the IP routing domain to better connect services.
  • a protection switching method is provided, which is applied to the first network device in the MAC switching domain.
  • the first network device is connected to the customer edge (CE) device; the MAC switching domain also includes two second network devices, and the two second network devices are connected in a one-to-one correspondence with the two third network devices in the IP routing domain.
  • the method includes: receiving an address resolution protocol (ARP) message from a CE device, where the ARP message includes a virtual local area network (VLAN) identifier and an IP address of the CE device.
  • ARP address resolution protocol
  • VLAN virtual local area network
  • the data transmission path group associated with the target service is determined, the target service is determined according to the VLAN identifier, and the data transmission path group includes data transmission paths between each of the two second network devices and the first network device.
  • the first network device does not receive the first bidirectional forwarding detection (BFD) control message from the target network device within a preset number of consecutive time intervals, it is determined that the data transmission path group is used for The first data transmission path for transmitting the first BFD control message, the target network device is one of the two third network devices, the first BFD control message is used to indicate that the first BFD session is in the connection establishment state, and the first BFD control message is The session address of the BFD session includes the IP address of the CE device and the IP address of the target network device.
  • a second data transmission path other than the first data transmission path in the data transmission path group is used to receive and/or send the service flow belonging to the target service.
  • the Layer 2 device ie, the first network device connected to the CE device can receive an ARP message from the CE device, and obtain the VLAN identifier and the IP address of the CE device from the ARP message.
  • the first network device can determine the data transmission path group associated with the target service.
  • the data transmission line group includes two of the second layer devices (that is, two second layer devices) included in the MAC switching domain.
  • a data transmission path between each of the network devices and the first network device, and the two second network devices are connected in a one-to-one correspondence with two of the three layer devices (third network devices) included in the IP routing domain.
  • One of the third network devices can serve as the target network device, establish a first BFD session with the IP address of the CE device and the IP address of the target network device as the session address, and send to the first network device an instruction for the first BFD The first BFD control packet in which the session is in the connection establishment state.
  • the first network device does not receive the first BFD control message within a preset number of consecutive time intervals, it indicates that the data transmission path between the target network device and the first network device may be faulty; for the target service As far as the service flow is concerned, it may not be able to be transmitted through the first data transmission path used for transmitting the first BFD control message in the data transmission path group.
  • the first network device can perform protection switching on the target service according to the data transmission path group and the data transmission path used to transmit the first BFD control message.
  • the second data transmission path other than the first data transmission path in the data transmission path group can be used to receive and/or send data packets belonging to the target service.
  • the layer 2 device connected to the CE device can sense the fault of the layer 3 device connected to the layer 2 device in the IP routing domain, and perform protection switching on the target service based on the fault sensed, so as to realize the layer 3 connection with the layer 2 device.
  • the layer 2 device in the MAC switching domain and the layer 3 device in the IP routing domain perform protection switching in coordination, which is beneficial to the IP routing domain and the MAC switching domain in the communication network to better connect services.
  • the first network device may also receive a second BFD control message from the target network device; the destination IP address of the second BFD control message is the IP address of the CE device, and the second BFD control message The source IP address of the message is the IP address of the target network device. Then respond to the second BFD control message to establish the first BFD session. Moreover, the first network device may also terminate the second BFD control message, and no longer forward the first BFD control message to the CE device connected to the first network device. In this way, the first network device can replace its connected CE device to establish the first BFD session with the target network device.
  • the first network device may send a message indicating that the first BFD session is in the connection establishment state to the target network device.
  • the third BFD control message so that the target network device determines the data between the first network device and the target network device by determining whether it has not received the third BFD control message within a preset number of consecutive time intervals. Whether the transmission path is faulty.
  • the first network device may also monitor that the destination IP address is the IP address of the CE device, and the source IP address is the target network device. And then determine whether the first data packet is the first BFD control packet used to indicate that the first BFD session is in the connection establishment state, so that the first network device can determine whether it is in the preset state
  • the first BFD control packet is not received within a number of consecutive time intervals.
  • the first BFD control message is terminated at the first network device and will not be forwarded to the CE device connected to the first network device, preventing the CE device from responding to the first BFD control message to increase the load or load of the CE device. Cause other problems.
  • the first network device may also determine the data transmission path used to transmit the second BFD control packet, and combine the first BFD session with the The data transmission path for transmitting the second BFD control message is associated.
  • the first network device may determine the data transmission path associated with the first BFD session as the first data transmission path for transmitting the first BFD control message.
  • the first network device may associate the IP address of the CE device and the IP address of the target network device with the data transmission path used to transmit the second BFD control message, so as to realize that the first BFD The session is associated with the data transmission path used to transmit the second BFD control message.
  • the first network device may monitor the first data packet whose destination IP address is the IP address of the CE device and the source IP address is the IP address of the target network device; and then determine the first data packet Whether it is the first BFD control packet used to indicate that the first BFD session is in the connection establishment state, so that the first network device can determine whether it does not receive the first BFD control packet within a preset number of consecutive time intervals .
  • the normal forwarding of the first data packet by the first network device will not affect the first BFD session and other services established between the CE device and the target network device.
  • the first network device when the first network device receives the fourth BFD control packet used to indicate that the first BFD session is in the disconnected state, the first network device may also determine the data transmission path group for Transmit the third data transmission path of the fourth BFD control message, and receive and/or send the service flow belonging to the target service according to the fourth data transmission path other than the third data transmission path in the data transmission path group. In this way, when the first network device cannot perceive whether the data transmission path between the first network device and the target network device is faulty, the protection switching is directly performed to ensure the continuity of the target service.
  • the data transmission path group may include, but is not limited to: pseudo wire group (PWG), VLAN transmission path group, or service provider virtual local area network (service provider virtual local area network, SVLAN) Transmission path group.
  • PWG pseudo wire group
  • VLAN virtual local area network
  • SVLAN service provider virtual local area network
  • the first network device includes a first interface, and the CE device is connected to the first interface; the target service is determined according to the VLAN identifier and the identifier of the first interface.
  • a protection switching method is provided, and the beneficial effects can be referred to the description in the first aspect.
  • the method is applied to a target network device in the IP routing domain, the target network device is one of the two third network devices included in the IP routing domain, the two third network devices and the two second networks in the MAC switching domain
  • the devices are connected in a one-to-one correspondence;
  • the MAC switching domain also includes a first network device, the first network device is connected to the user edge CE device, and the two second network devices are connected to the first network device through different data transmission paths.
  • the method includes: establishing a first BFD session with the IP address of the CE device and the IP address of the target network device as the session address; sending to the first network device a first BFD control report for indicating that the first BFD session is in a connection establishment state
  • the first BFD control message is transmitted to the first network device through the data transmission path between the second network device connected to the target network device and the first network device.
  • the target network device when the target network device does not receive the third BFD control message for indicating that the first BFD session is in the connection establishment state within a preset number of consecutive time intervals, the protection switching is performed,
  • the source IP address of the third BFD control message is the IP address of the CE device, and the destination IP address of the third BFD control message is the IP address of the target network device.
  • the IP routing domain further includes a fourth network device, the two third network devices are respectively connected to the fourth network device, and the target network device establishes a second BFD session with the fourth network device.
  • the target network device may also send a fourth BFD control message for indicating that the first BFD session is in the disconnected state to the first network device when the second BFD session is in the disconnected state, and perform protection switching.
  • the fourth BFD The control message is transmitted to the first network device through the data transmission path between the second network device connected to the target network device and the first network device.
  • a communication device is provided, and the beneficial effects can be referred to the description in the first aspect.
  • the communication device is applied to the first network device in the MAC switching domain. More specifically, the communication device may be the first network device, or it may be a module, chip or system on chip deployed in the first network device.
  • the first network device is connected to the user edge CE device; the MAC switching domain also includes two second network devices, and the two second network devices are connected in a one-to-one correspondence with the two third network devices in the IP routing domain.
  • the communication device includes: a first transceiver unit, configured to receive an address resolution protocol ARP message from a CE device; wherein, the ARP message includes a virtual local area network VLAN identifier and an IP address of the CE device.
  • a processing unit configured to determine a data transmission path group associated with a target service; wherein the target service is determined according to a VLAN identifier, and the data transmission path group includes a data transmission path between each of the two second network devices and the first network device; And, when the first network device does not receive the first BFD control message from the target network device within a preset number of consecutive time intervals, it is determined that the first BFD control message in the data transmission path group is used to transmit the first BFD control message.
  • the second transceiver unit is configured to use a second data transmission path other than the first data transmission path in the data transmission path group to receive and/or send a service stream belonging to the target service.
  • the second transceiving unit is further configured to receive a second BFD control message from a target network device; wherein, the destination IP address of the second BFD control message is the IP address of the CE device, The source IP address of the second BFD control message is the IP address of the target network device.
  • the processing unit is further configured to respond to the second BFD control message to establish the first BFD session.
  • the second transceiving unit is further configured to send a third BFD control message to the target network device; where the third BFD control message is used to indicate that the first BFD session is in a connection establishment state.
  • the second transceiving unit is further configured to receive the first data packet; wherein the destination IP address of the first data packet is the IP address of the CE device, and the source IP address of the first data packet is The IP address of the target network device.
  • the processing unit is also used to determine whether the first data packet is the first BFD control message; if the first data packet is the first BFD control message, terminate the first BFD control message.
  • the processing unit is further configured to determine a data transmission path used to transmit the second BFD control message, and transmit the first BFD session to the data transmission path used to transmit the second BFD control message Path association.
  • the processing unit is specifically configured to determine the data transmission path associated with the first BFD session as the first data transmission path for transmitting the first BFD control message.
  • the processing unit is specifically configured to associate the IP address of the CE device and the IP address of the target network device with the data transmission path used to transmit the second BFD control message.
  • the second transceiving unit is further configured to receive the first data packet; wherein the destination IP address of the first data packet is the IP address of the CE device, and the source IP address of the first data packet is The IP address of the target network device.
  • the processing unit is also used to determine whether the first data packet is the first BFD control packet.
  • the first transceiver unit is also used to send the first data packet to the CE device.
  • the processing unit is further configured to, when receiving the fourth BFD control packet from the target network device, determine the third data transmission path group used to transmit the fourth BFD control packet. Data transmission path; wherein, the fourth BFD control message is used to indicate that the first BFD session is in a disconnected state.
  • the second transceiver unit is further configured to use a fourth data transmission path in the data transmission path group except the third data transmission path to receive and/or send a service stream belonging to the target service.
  • the data transmission path group may include, but is not limited to: PWG, VLAN transmission path group, or SVLAN transmission path group.
  • the first network device includes a first interface, and the CE device is connected to the first interface; the target service is determined according to the VLAN identifier and the identifier of the first interface.
  • a communication device is provided, and the beneficial effects can be referred to the description in the first aspect.
  • the communication device is applied to a target network device in an IP routing domain. More specifically, the communication device may be a target network device, or a module, chip, or system-on-chip deployed in the target network device.
  • the target network device is one of the two third network devices included in the IP routing domain, and the two third network devices are connected in a one-to-one correspondence with the two second network devices in the MAC switching domain; the MAC switching domain also includes the first A network device, the first network device is connected to the user edge CE device, and the two second network devices are respectively connected to the first network device through different data transmission paths.
  • the communication device includes: a processing unit configured to establish a first BFD session; wherein the session address of the first BFD session includes the IP address of the CE device and the IP address of the target network device.
  • the transceiver unit is configured to send a first BFD control message to the first network device; where the first BFD control message is used to indicate that the first BFD session is in a connection establishment state, and the first BFD control message is connected through the target network device
  • the data transmission path between the second network device and the first network device is transmitted to the first network device.
  • the processing unit is further configured to perform protection switching when the target network device does not receive the third BFD control packet within a preset number of consecutive time intervals; wherein, the third BFD
  • the source IP address of the control message is the IP address of the CE device, and the destination IP address of the third BFD control message is the IP address of the target network device.
  • the IP routing domain further includes a fourth network device, the two third network devices are respectively connected to the fourth network device, and the target network device establishes a second BFD session with the fourth network device.
  • the transceiver unit is also used to send a fourth BFD control message to the first network device when the second BFD session is in a disconnected state, and trigger the processing unit to perform protection switching; wherein, the fourth BFD control message is used to indicate The first BFD session is in a disconnected state, and the fourth BFD control packet is transmitted to the first network device through a data transmission path between the second network device connected to the target network device and the first network device.
  • a network device including a memory and a processor, where executable code is stored in the memory, and when the processor executes the executable code, the method according to any one of the first aspect or the second aspect is implemented.
  • a computer-readable storage medium for storing instructions.
  • the instructions When the instructions are executed by a processor of a network device, the network device implements the method described in any one of the first aspect or the second aspect
  • a computer program product includes computer program code.
  • the computer program code runs on a computer, the computer executes any one of the first or second aspects described above. The method described.
  • a chip system in an eighth aspect, includes a processor, configured to implement the functions of the communication device described in the foregoing aspects, for example, receiving or processing the method described in the first aspect/second aspect.
  • the chip system further includes a memory, and the memory is used to store program instructions and/or data.
  • the chip system can be composed of chips, and can also include chips and other discrete devices.
  • FIG. 1 is a schematic diagram of a business scenario to which the technical solution provided in an embodiment of the application is applicable.
  • Fig. 2 is a flowchart of a protection switching method provided in an embodiment of the application.
  • FIG. 3 is a schematic diagram of a process of cooperative protection switching between a layer 2 device and a layer 3 device in an embodiment of the application.
  • FIG. 4 is a schematic diagram of a process of establishing a BFD session between a layer 3 device and a layer 2 device in an embodiment of the application.
  • Fig. 5 is a schematic structural diagram of a communication device provided in an embodiment of the application.
  • FIG. 6 is a schematic structural diagram of another communication device provided in an embodiment of this application.
  • FIG. 7 is a schematic structural diagram of a network device provided in an embodiment of this application.
  • Layer 2 devices refer to network devices that work at the data link layer, such as switches. When the Layer 2 device receives a data packet from another device, it can forward the data packet according to the MAC address included in the data packet.
  • Layer 3 devices refer to network devices that work at the network layer, such as routers. When the layer 3 device receives a data packet from another device, it can forward the data packet according to the IP address included in the data packet.
  • a network device may have the capabilities of both a layer 2 device and a layer 3 device.
  • some switches may have both the capabilities of Layer 2 devices and the capabilities of Layer 3 devices. If it has both the capabilities of a layer 2 device and a layer 3 device, the network device may be configured to forward the data packet according to the MAC address included in the data packet it receives, or it may be configured to forward the data packet according to the received data packet. The IP address included in the data packet forwards the data packet.
  • FIG. 1 is a schematic diagram of a business scenario to which the technical solution provided in an embodiment of the application is applicable.
  • the communication network includes one or more CE devices, MAC switching domains, and IP routing domains.
  • the MAC switching domain includes multiple layer 2 devices
  • the IP routing domain includes multiple layer 3 devices.
  • the data transmission path between the second layer device M2 and the second layer device M3 and the MAC switching domain and the IP routing domain respectively includes: the data transmission path between the second layer device M2 and the third layer device R1, and the second layer device M3 and the third layer device Data transmission path between R2.
  • the protected target service can be protected and switched, and the service flow belonging to the target service is transmitted through the other data transmission path that has not failed to ensure the service to which the service flow belongs Continuity.
  • the service flow belonging to the target service refers to one or more data packets belonging to the target service.
  • the layer 2 device M1 is also called the first network device; the layer 2 device M2 and the layer 2 device M3 are also called the second network device; the layer 3 device R1 and the layer 3 device R2 are also called The third network device; the third layer device R3 is also called the fourth network device.
  • the first network device may be configured with one or more interfaces for connecting CE devices.
  • the first network device is configured with multiple interfaces for connecting CE devices, different CE devices can be connected.
  • Layer 2 device M1 is configured with interfaces GE1 and GE2, and connects to CE device 1 through interface GE1, and connects to CE device 2 through interface GE2.
  • the data transmission path between the first network device and the second network device may include one or more layer 2 devices.
  • the layer 2 device M1 and the layer 2 device M2 are directly connected, but the data transmission path between the layer 2 device M1 and the layer 2 device M3 also includes the layer 2 device M4.
  • the data transmission path between the third network device and the fourth network device may include one or more layer-3 devices.
  • the three-layer device R1 and R3 are directly connected, but the data transmission path between the three-layer device R2 and R3 also includes the three-layer device R4.
  • the layer 2 device in the MAC switching domain and the layer 3 device in the IP routing domain can each use different methods to perform fault detection on the data transmission path.
  • the MAC switching domain and the IP routing domain usually adopt different protection switching technologies. For example, the MAC switching domain adopts PW fast protection switching (FPS) technology for protection switching, and the IP routing domain adopts virtual router redundancy protocol (VRRP) technology for protection switching. This will cause the devices in the two domains to not perceive each other's failures and fail to perform coordinated protection switching.
  • PW fast protection switching FPS
  • VRRP virtual router redundancy protocol
  • the layer 3 device R1 in the IP routing domain fails, causing other layer 3 devices connected to it to perform protection switching, the layer 2 device M1 in the MAC switching domain cannot sense the fault of the layer 3 device R1 and will not be timely Perform protection switching.
  • the layer 3 device in the IP routing domain (such as the layer 3 device R2 or the layer 3 device R3 connected to the layer 3 device R1) may receive and/or send through the data transmission path between R2 and M3 after protection switching The service flow belonging to a certain service will no longer receive or send the service flow belonging to this service through the data transmission path between R1 and M2.
  • the layer 2 device M1 cannot sense the fault of the layer 3 device R1, the layer 2 device M1 fails to perform protection switching in coordination with the layer 3 device, and the layer 2 device M1 may still be between the layer 2 device M1 and the layer 2 device M2
  • the data transmission path receives and/or sends the service flow belonging to this service, which leads to the inefficient docking service between the MAC switching domain and the IP routing domain.
  • the Layer 2 device (first network device) connected to the CE device receives an ARP message from the CE device, and obtains the VLAN identifier and the IP address of the CE device from the ARP message. Then, for the target service determined according to the VLAN identifier, the first network device determines the data transmission path group associated with the target service.
  • the data transmission line group includes two of the two layer 2 devices (two second layer devices) included in the MAC switching domain.
  • a data transmission path between each of the network devices and the first network device, and the two second network devices are connected in a one-to-one correspondence with two of the three layer devices (third network devices) included in the IP routing domain.
  • one of the third network devices can serve as the target network device, establish a first BFD session with the IP address of the CE device and the IP address of the target network device as the session address, and send to the first network device an instruction for the first BFD session.
  • the first BFD control packet in which a BFD session is in a connection establishment state.
  • the first network device When the first network device does not receive the first BFD control message within a preset number of consecutive time intervals, it indicates that the data transmission path between the target network device and the first network device is faulty; the service flow of the target service It may not be possible to perform transmission through the first data transmission path used for transmitting the first BFD control message in the data transmission path group.
  • the first network device may use a second data transmission path other than the first data transmission path in the data transmission path group to receive and/or send data packets belonging to the target service.
  • the layer 2 device connected to the CE device can sense the fault of the layer 3 device connected to the layer 2 device in the IP routing domain, and perform protection switching on the target service based on the fault sensed, so that the layer 2 device in the MAC switching domain can Cooperating with the layer 3 equipment in the IP routing domain to perform protection switching is beneficial to the IP routing domain and the MAC switching domain in the communication network to better connect the target service.
  • Fig. 2 is a flowchart of a protection switching method provided in an embodiment of the application. As shown in Figure 2, the method may at least include the following steps.
  • Step 201 The first network device receives an ARP message from the CE device.
  • the ARP message includes the IP address and VLAN identification of the CE device. More specifically, the source IP address of the ARP message is the IP address of the CE device, and the ARP message may also include a VLAN identifier.
  • Step 203 The first network device determines a data transmission path group associated with the target service.
  • the target service is determined according to the VLAN identifier included in the ARP message; the data transmission path group includes a data transmission path between each of two second network devices and the first network device.
  • Step 205 When the first network device does not receive the first BFD control message from the target network device within a preset number of consecutive time intervals, the first network device determines that the data transmission path group is used to transmit the first BFD The first data transmission path of the control message.
  • the first BFD control message is used to indicate that the first BFD session is in the connection establishment state; the session address of the first BFD session includes the IP address of the CE device and the IP address of the target network device; the target network device can complete the establishment of the first BFD session.
  • After a BFD session periodically send the first BFD control message to the first network device at a corresponding time interval.
  • the first network device does not receive the first BFD control message from the target network device within a preset number of consecutive time intervals, it indicates that the target network device may have failed. For the service flow belonging to the target service, It may not be possible to perform transmission through the first data transmission path used for transmitting the first BFD control message in the data transmission path group.
  • Step 207 The first network device uses a second data transmission path other than the first data transmission path in the data transmission path group to receive and/or send data packets belonging to the target service.
  • a layer 3 device connected to a layer 2 device in an IP routing domain fails, other layer 3 devices connected to the layer 3 device in the IP routing domain can perceive the failure of the layer 3 device.
  • Other Layer 3 devices can perform protection switching based on the fault it senses.
  • the layer 2 device connected to the CE device can sense the fault of the layer 3 device connected to the layer 2 device in the IP routing domain, and perform protection switching based on the fault sensed, and finally realize the coordinated operation of the layer 2 device and the layer 3 device Protection switching is conducive to the docking of target services between the MAC switching domain and the IP routing domain.
  • the user can configure the layer 2 device used to connect to the CE device in an actual application scenario, so that the layer 2 device performs the protection switching method provided in the embodiment of this application on a specific CE device .
  • the corresponding "BFD Session Proxy Enable” function and/or “BFD Session Synchronization Function" are configured, and the Layer 2 device is configured according to the user Operation of the interface to determine whether to enable BFD session proxy or BFD session synchronization for the interface.
  • the layer 2 device determines whether to enable it based on the configuration information from other communication devices, or according to the configuration information preset in the layer 2 device. Synchronize the BFD session proxy or BFD session of the interface.
  • the Layer 2 device For each interface used to connect the CE device in the Layer 2 device, if the BFD session proxy for the interface is enabled, the Layer 2 device will replace the CE device connected to the interface with the IP address of the CE device connected to the interface.
  • the Layer 3 device in the IP routing domain establishes a BFD session, completes the fault detection of the Layer 3 device based on the BFD session, and performs protection switching when it senses that the Layer 3 device may malfunction.
  • the Layer 2 device M1 determines to enable the BFD session proxy for the interface GE1
  • the layer 2 device M1 and the Layer 3 device in the IP routing domain can be as shown in Figure 3.
  • the layer 2 device M1 may perform step 301 to receive an ARP packet from the CE device 1 connected to the interface GE1.
  • the CE device 1 is a layer 3 device working at the network layer, and the CE device 1 can broadcast ARP messages to the VLAN, for example, broadcast an ARP request or an ARP response to the VLAN.
  • the source IP address of the ARP message is the IP address of the CE device, and the ARP message also includes the VLAN identification of the VLAN.
  • the Layer 2 device M1 may match the format of the packet received by the interface GE1 according to an access control list (ACL) to determine whether the packet is an ARP packet from CE device 1. .
  • ACL access control list
  • Layer 2 device M1 can perform step 302 for the ARP message to obtain the IP address and VLAN identifier of CE device 1 from the ARP message.
  • the Layer 2 device M1 can parse the ARP message, obtain the source IP address of the ARP message from the IP header of the ARP message, and the source IP address of the ARP message is the IP address of CE device 1. , And obtain the VLAN ID from the ARP message.
  • the layer 2 device M1 may also perform a process similar to the above step 301 and step 302 on the interface GE2. If the Layer 2 device M1 has not determined to enable the BFD session proxy for the interface GE2, and has not determined to enable the BFD session synchronization for the interface GE2, it does not need to perform processing similar to the above step 301 and step 302 on the interface GE2. Avoid excessive load on the second-tier device M1.
  • the Layer 2 device M1 may also record the identifier of the interface used to receive the ARP message, the IP address of the CE device included in the ARP message, and the VLAN identifier in the attribute information table. In this way, it is beneficial to determine the target service to be protected and its associated data transmission path group according to the information recorded in the attribute information table in the subsequent process, and replace the CE device to establish the first BFD session with the layer 3 device in the IP routing domain. .
  • the identifier of the interface GE1 is GE1
  • the IP address of the CE device 1 included in the ARP message received by the interface GE1 is CE_IP1
  • the VLAN identifier included in the ARP message is VLAN_1.
  • the Layer 2 device M1 can maintain the attribute information table shown in Table 1 below.
  • the layer 2 device M1 may perform step 303 to determine the data transmission path group associated with the target service.
  • the data transmission path group may include a data transmission path between the second layer device M1 and the second layer device M2, and a data transmission path between the second layer device M1 and the second layer device M3.
  • the target service may be determined according to the VLAN identifier included in the ARP message.
  • the target service may be determined according to the VLAN identifier included in the ARP message and the interface used to receive the ARP message.
  • the layer 2 device M1 may also configure one data transmission path in the data transmission path group as the main data transmission path, and configure the other data transmission path in the data transmission path group as the backup data transmission path.
  • the main data transmission path is used to receive and/or send the service flow belonging to the target service.
  • the data transmission path group associated with the target service may include, but is not limited to, a PWG, a VLAN transmission path group, or an SVLAN transmission path group.
  • the data transmission path between each of the layer 2 device M2, the layer 2 device M3 and the layer 2 device M1 may include a PW, a VLAN transmission path, or an SVLAN transmission path.
  • the Layer 2 device M1 maintains the attribute information table shown in Table 1 above, and supports PW and FPS.
  • the layer 2 device M1 can configure its associated PWG for the target service, and the PWG can include the PW between the layer 2 device M1 and the layer 2 device M2 , PW between the second-tier device M1 and the second-tier device M3.
  • the PW between the second-tier device M1 and the second-tier device M2 is denoted as PW1
  • the PW between the second-tier device M1 and the second-tier device M3 is denoted as PW2 in the following.
  • PW1 and PW2 respectively configured as the primary and backup PWs as an example
  • the Layer 2 device M1 receives a service flow from CE device 1 that belongs to the target service
  • the service flow is encapsulated into PW1
  • the service flow is passed through PW1 Transmitted to the second layer device M2
  • the second layer device M2 sends the service flow to the third layer device R1
  • the third layer device R1 further forwards the service flow, for example, the third layer device R1 forwards the service flow To the third floor equipment R3.
  • the service flow from the third layer device R3 and belonging to the target service can be transmitted to the CE device 1 through the third layer device R1, the second layer device M2, and the second layer device M1 in sequence.
  • the layer 3 device R1 or the layer 3 device R2 in the IP routing domain can be used as the target network device to establish the first BFD session with the IP address of the CE device 1 connected to the interface GE1 and the IP address of the target network device as the session address.
  • the target network device as the third-tier device R1 as an example, the third-tier device R1 can cooperate with the second-tier device M1 to complete step 304a, and establish the first session address with the IP address of the third-tier device R1 and the IP address of the CE device 1 as the session address.
  • a BFD session is an example, the third-tier device R1 can cooperate with the second-tier device M1 to complete step 304a, and establish the first session address with the IP address of the third-tier device R1 and the IP address of the CE device 1 as the session address.
  • FIG. 4 is a schematic diagram of the process of establishing a first BFD session between the layer 3 device R1 and the layer 2 device M1.
  • the session state is down to indicate that the BFD session is in a connection interrupted state
  • the session state is up to indicate that the BFD session is in the connection establishment state
  • the session state is init to indicate that the BFD session is in the initial state.
  • the Layer 3 device R1 can first start the state machine of the first BFD session, and record the session state of the first BFD session through the state machine.
  • you can first set the session state recorded by the state machine to down, and then execute Step 3041: Send a BFD control packet with a session status of down to the layer 2 device M1.
  • the destination IP address of the BFD control message is the IP address of CE device 1, and the source IP address of the BFD control message is the IP address of the layer 3 device R1.
  • the BFD control message is also referred to as the second BFD control message in the embodiment of the present application.
  • the second BFD control message will first be sent to the layer 2 device M2 corresponding to the layer 3 device R3.
  • the second BFD control message is encapsulated by the layer 2 device M2 into the data transmission path between M2 and M1, and then transmitted to the layer 2 device M1 by the data transmission path between the layer 2 device M2 and the layer 2 device M1.
  • the layer 2 device M1 Since the layer 2 device M1 has determined to enable the BFD session proxy for the interface GE1, when the layer 2 device M1 receives a data packet from the IP routing domain, it can detect the data packet according to the IP address of the CE device 1 connected to the interface GE1 Whether it is the second BFD control packet to be sent to CE device 1. It can be understood that the BFD control message has a specific structure. The Layer 2 device M1 can match the data structure of the data packet from the IP routing domain to detect whether the data packet is a BFD control message, and then determine whether the data packet is a pending data packet. The second BFD control packet sent to CE device 1.
  • the Layer 2 device M1 can query whether the IP address of the CE device in the foregoing Table 1 recorded by it is the same as the destination IP address of the data packet. If it is, it is determined whether the data packet is a BFD control packet with the session status down. Then, if the data packet is a BFD control packet with the session status down, the layer 2 device M1 can obtain the source and destination IP addresses of the second BFD control packet to obtain the IP address of the layer 3 device R1 and the CE device 1’s IP address. Then, the layer 2 device M1 responds to the second BFD control message according to the IP address of the layer 3 device R1 and the IP address of the CE device 1, and completes the establishment of the first BFD session with the layer 3 device R1.
  • the layer 2 device M1 responding to the second BFD control message may include, but is not limited to, the layer 2 device M1 and the layer 3 device R1 cooperating to complete the following steps 3042 to 3048.
  • step 3042 the layer 2 device M1 switches the session state of the first BFD session to init.
  • the layer 2 device M1 when the layer 2 device M1 receives the second BFD control message, it can start the state machine of the first BFD session, and record the session state of the first BFD session through the state machine.
  • the state machine can record the state machine first. Set the session state to down, and then switch the session state recorded by the state machine from down to init.
  • step 3043 the layer 2 device M1 sends a BFD control packet with the session state of init to the layer 3 device R1.
  • the destination IP address of the BFD control packet is the IP address of the layer 3 device R1 of the second BFD control packet
  • the source IP address is the IP address of CE device 1 obtained by the layer 2 device M1 from the second BFD control packet address.
  • the layer 3 device R1 After the layer 3 device R1 receives the BFD control message from the layer 2 device M1 with the session state being init, it may perform step 3044 to switch the session state of the first BFD session to init.
  • the layer 3 device R1 may update the state machine of the first BFD session, and switch the session state recorded by the state machine from down to init.
  • step 3045 the layer 3 device R1 sends a BFD control packet with the session state of init to the layer 2 device M1.
  • the layer 2 device M1 can continuously monitor the BFD control packets whose destination IP address is the IP address of the CE device 1, the source IP address is the IP address of the layer 3 device R1, and the session state is init. After the layer 2 device M1 successfully monitors the BFD control message, step 3046 may be executed to switch the session state of the first BFD session to up. Specifically, the Layer 2 device M1 may update the state machine of the first BFD session, and switch the session state recorded by the state machine from init to up.
  • the layer 2 device M1 After the layer 2 device M1 switches the session state of the first BFD session to up, the layer 2 device M1 completes the establishment of the first BFD session, and can perform step 3047 to send a BFD control packet with the session state of up to the layer 3 device R1.
  • the source IP address of the BFD control message is the IP address of CE device 1
  • the destination IP address of the BFD control message is the IP address of the layer 3 device R1.
  • step 3048 can be performed to transfer the first BFD session The session state of switch to up.
  • the layer three device R1 may update the state machine of the first BFD session, switch the session state recorded by the state machine from init to UP, and complete the establishment of the first BFD session.
  • the Layer 2 device M1 may terminate the BFD control message after completing the processing of the BFD control message. In other words, the layer 2 device M1 can discard the BFD control packet after finishing processing the BFD control packet sent by R1 to the CE device 1, and no longer forward the BFD control packet to the CE device 1 connected to the interface GE1 .
  • the layer 3 device R1 may also establish a second BFD session with other layer 3 devices.
  • the layer 3 device R1 can also cooperate with the layer 3 device R3 to complete step 304b, and establish a second BFD session with the IP address of the layer 3 device R1 and the IP address of the layer 3 device R3 as the session address.
  • the process of establishing the second BFD session between the layer 3 device R1 and the layer 3 device R3 is similar to the process of establishing the first BFD session between the layer 3 device R1 and the layer 2 device M1 shown in FIG. The process of establishing the second BFD session with the layer 3 device R3 will be described in detail.
  • the layer 2 device M1 may also perform step 305, Determine the data transmission path used to transmit the second BFD control packet in the data transmission path group, and associate the data transmission path used to transmit the second BFD control packet with the first BFD session.
  • the layer two device M1 may associate the two session addresses of the first BFD session with the data transmission path used to transmit the second BFD control message. More specifically, the IP address of the CE device 1 and the IP address of the layer 3 device R1 may be associated with the data transmission path used to transmit the second BFD control message.
  • the data transmission path between the second layer device M2 and M1 is PW1; for the BFD control with the destination IP address being the IP address of CE device 1, the source IP address being the IP address of the third layer device R1 and the session status being down
  • Layer 2 device M1 can use the mapping relationship table described in Table 2 to change the IP address of CE device 1 to "CE_IP1".
  • the IP address "R1_IP" of the layer 3 device R1 is associated with PW1, so that the first BFD session is associated with the data transmission path used to transmit the second BFD control message.
  • serial number, the IP address of the CE device, the IP address of the layer 3 device, the data transmission path, and the field values in the foregoing Table 2 are only used to assist in describing the technical solutions provided in the embodiments of this application. In actual applications, the aforementioned fields and field values can be replaced with real values.
  • the layer 3 device R1 may periodically send the first BFD control message to the layer 2 device M1 after completing the establishment of the first BFD session.
  • the source IP address of the first BFD control message is the IP address of layer 3 device R1
  • the destination IP address of the first BFD control message is the IP address of CE device 1
  • the first BFD control message is used to indicate the first
  • the session state is in the connection establishment state, that is, the session state included in the first BFD control packet is the session state "up" recorded by the state machine of the first BFD session initiated by the layer 3 device R1. So that the layer 2 device M1 executes step 306a to perform fault detection on the data transmission path between the layer 2 device M1 and the layer 3 device R1.
  • the layer 2 device M1 can continuously monitor the first data packet whose destination IP address is the IP address of CE device 1 and the source IP address is the IP address of the layer 3 device R1; for the first data received by the layer 2 device M1 Packet, it can be further determined whether the first data packet is a first BFD control packet used to indicate that the first BFD session is in the connection establishment state. If the first data packet is the first BFD control message, process and terminate the first BFD control message.
  • the layer 2 device M1 can determine that the data transmission path between the layer 2 device M1 and the layer 3 device R1 may be faulty For example, the layer 2 device M2 or the layer 3 device R3 fails; for the service flow belonging to the target service, it may not be able to be transmitted through the first data transmission path used to transmit the first BFD control message in the data transmission path group.
  • the layer 2 device M1 may send the layer 2 device M1 to the layer 3 device after completing the establishment of the first BFD session.
  • R1 periodically sends the third BFD control message.
  • the source IP address of the third BFD control message is the IP address of the second layer device M1
  • the destination IP address of the third BFD control message is the IP address of CE device 1
  • the third BFD control message is used to indicate the first
  • the session state is in the connection establishment state. That is, the session state included in the third BFD control packet is the session state "up" recorded by the state machine of the first BFD session initiated by the layer 2 device M1.
  • the layer 3 device R1 executes step 306b to perform fault detection on the data transmission path between the layer 2 device M1 and the layer 3 device R1.
  • the layer 3 device R1 can continuously monitor the second data packet whose destination IP address is the IP address of the layer 3 device R1 and the source IP address is the IP address of the CE device 1; for the second data packet received by the layer 3 device R1 Packet, it can be further determined whether the second data packet is a third BFD control packet used to indicate that the first BFD session is in the connection establishment state.
  • the layer 3 device R1 does not receive the third BFD control packet within the preset number of consecutive time intervals, it means that the data transmission path between the layer 2 device M1 and the layer 3 device R1 is faulty, such as the layer 2 device M1 Or the layer 2 device M2 fails; the layer 3 device R1 may not continue to normally receive and/or send the service flow belonging to the target service on the data transmission path between the layer 2 device M2 and the layer 3 device R1.
  • the layer 3 device R1 and the layer 3 device R3 can also send and receive BFD control messages to each other, and respectively perform fault detection on the corresponding data transmission path.
  • the process of implementing fault detection on the data transmission path in steps 306c and 306d will not be repeated here.
  • the layer 2 device M1 can perform step 307 to determine the data transmission path group associated with the target service A data transmission path used to transmit the first BFD control message.
  • the layer two device M1 may determine the data transmission path used to transmit the second BFD control message as the first data transmission path used to transmit the first BFD control message.
  • the layer 2 device M1 can query the above table 2 according to the session address of the first BFD session, that is, the IP address of the CE device 1 and the IP address of the layer 3 device R1, to determine the data used to transmit the second BFD control message
  • the transmission path is PW1, and PW1 may be determined as a data transmission path for transmitting the first BFD control message.
  • the layer two device M1 may further execute step 308a to perform protection switching according to the data transmission path used to transmit the first BFD control message and the data transmission path group associated with the target service.
  • the layer two device M1 can use the second transmission path in the data transmission path group other than the first data transmission path to receive and/or send the service flow belonging to the target service.
  • the layer 3 device R1 when the layer 3 device R1 detects that the data transmission path between the layer 3 device R1 and the layer 3 device R3 is faulty in step 306c, or the layer 3 device R1 closes the first BFD session under the control of the user
  • the third layer device R1 can send to the second layer device M1
  • the source IP address is the IP address of the third layer device R1
  • the destination IP address is the IP address of the CE device 1
  • the session status is “admin down” or “down”.
  • the layer 2 device M1 For the layer 2 device M1, if the layer 2 device M1 receives the fourth BFD control packet indicating that the first BFD session is in the disconnected state, the layer 2 device M1 cannot determine the layer 2 device M1 and the layer 3 Whether the data transmission path between the devices R1 is faulty. In order to ensure the continuity of the target service, the layer 2 device M1 may determine the third data transmission path for transmitting the fourth BFD control message from the data transmission path group, and then according to the third data transmission path and the data transmission path group Perform protection switching. After the layer 2 device M1 performs protection switching, it can receive and/or send the service flow belonging to the target service through the fourth data transmission path except the third data transmission path in the data transmission path group.
  • the three-layer device R1 detects that the data transmission path between the three-layer device R1 and the three-layer device R3 may be faulty in step 306c, or the three-layer device R1 closes the first BFD under the control of the user During the session, after the layer 3 device R1 finishes sending the fourth BFD control message to the layer 2 device M1, it may perform protection switching in step 308b, so that the layer 2 device M1 and the layer 3 device R1 perform protection switching in coordination.
  • the layer 3 device R1 may perform protection switching in step 308b.
  • the layer 3 device R3 may perform protection switching in step 308c.
  • the faulty three-layer device and the protection switching technology supported by each three-layer device, the two-layer device M1 and the three-layer device R1 or the three-layer device R3 are coordinated.
  • the service flow from the CE device and belonging to the target service can be transmitted to the layer 3 device R3 through the corresponding data transmission path after reaching the layer 3 device R2 in the IP routing domain.
  • the layer 3 device R3 may detect that the data transmission path between the layer 3 device R1 and the layer 3 device R3 may be faulty in step 306d, and then perform protection switching in step 308c, Instead of receiving/sending the service flow belonging to the target service from the MAC switching domain through R1, but receiving/sending the service flow belonging to the target service from the MAC switching domain through the three-layer device R2.
  • the layer 2 device M1 and the layer 3 device R3 cooperatively perform protection switching, for the service flow from the CE device 1 that belongs to the target service, the layer 2 device M1 can communicate with the layer 2 device through the layer 2 device M1.
  • the data transmission path between M3 is sent to the second-tier device M3, and the second-tier device M3 sends the service stream to the correspondingly connected third-tier device R2, and then the third-tier device R2 sends the service stream to the third-tier device R3.
  • the three-layer device R1 is similar. As shown in Figure 3, after the layer 2 device M1 and the layer 3 device R1 cooperatively perform protection switching, for the service flow from the CE device 1 that belongs to the target service, the layer 2 device M1 can communicate with the layer 2 device through the layer 2 device M1. The data transmission path between M3 is sent to the layer 2 device M3, and the layer 2 device M3 sends the service stream to the layer 3 device R2 through the data transmission path between the layer 2 device M3 and R2. After that, the service flow can be sent to the three-layer device R1, and the three-layer device R1 sends the service flow to the three-layer device R3; or, the three-layer device R2 directly sends the service flow to the three-layer device R3.
  • the layer 2 device can monitor the CE device connected to the interface according to the IP address of the CE device connected to the interface
  • the BFD session established with the layer 3 device in the IP routing domain completes the fault detection of the layer 3 device by monitoring the BFD session, and performs protection switching when it senses that the layer 3 device may malfunction.
  • the Layer 2 device M1 determines to enable BFD session synchronization on the interface GE1
  • the Layer 2 device M1 and the Layer 3 device in the IP routing domain cooperate to perform the protection switching process
  • the difference in step 304a shown in FIG. 3 is that the layer 3 device R1 and the CE device 1 establish a first BFD session with the IP address of the layer 3 device R1 and the IP address of the CE device 1 as the session address.
  • the layer 2 device M1 determines to enable synchronization of the BFD session to the interface GE1, when the layer 2 device M1 receives a data packet from the IP routing domain If the data packet is the second BFD control packet to be sent to CE device 1 according to the IP address of CE device 1 connected to interface GE1, if the data packet is the second BFD control packet to be sent to CE device 1 BFD control message, start the state machine of the first BFD session, and switch the session state of the state machine from down to init; moreover, the second layer device M1 also needs to forward the second BFD control message to CE device 1. In this way, the CE device 1 and the Layer 3 device R1 perform a process similar to FIG. 4 to complete the establishment of the first BFD session.
  • the layer 2 device M1 monitors the first BFD session established by the layer 3 device R1 and the CE device 1, so as to realize the connection between the layer 2 device M1 and the layer 3 device R1. Fault detection is performed on the data transmission path between.
  • the layer 2 device M1 can continuously monitor the first data packet whose destination IP address is the IP address of CE device 1 and the source IP address is the IP address of the layer 3 device R1; for the layer 2 device M1 to receive To determine whether the first data packet is a first BFD control packet used to indicate that the first BFD session is in a connection establishment state. If the first data packet is the first BFD control message, update the state machine of the first BFD session and forward the first BFD control message to the CE device 1.
  • the layer 2 device M1 can determine that the data transmission path between the layer 2 device M1 and the layer 3 device R1 may be faulty For example, the layer 2 device M2 or the layer 3 device R3 fails; for the service flow belonging to the target service, it may not be able to be transmitted through the first data transmission path used to transmit the first BFD control message in the data transmission path group.
  • the third BFD control message from the CE device 1 is sent to the layer 3 device R1 via the layer 2 device M1.
  • the layer 3 device R1 performs fault detection on the data transmission path between the CE device 1 and the layer 3 device R1.
  • the third layer device R1 does not receive the third BFD control packet within a preset number of consecutive time intervals, it indicates the data transmission path between the CE device 1 and the layer three device R1 A failure occurs, such as a failure of the CE device 1, the second-tier device M1, or the second-tier device M2; the third-tier device R1 may not continue to receive and/or normally on the data transmission path between the second-tier device M2 and the third-tier device R1 Send the business flow belonging to the target business.
  • an embodiment of the present application also provides a communication device 500.
  • the communication device 500 includes: a first transceiving unit 501 configured to perform step 201 in FIG. 2.
  • the processing unit 502 is configured to execute steps 203 and 205 in FIG. 2.
  • the second transceiver unit 503 is configured to perform step 207 in FIG. 2.
  • the second transceiving unit 503 is further configured to receive a second BFD control packet from a target network device; wherein, the destination IP address of the second BFD control packet is the IP address of the CE device , The source IP address of the second BFD control message is the IP address of the target network device.
  • the processing unit 502 is further configured to respond to the second BFD control message to establish the first BFD session.
  • the second transceiver unit 503 is further configured to send a third BFD control packet to the target network device; where the third BFD control packet is used to indicate that the first BFD session is in a connection establishment state.
  • the second transceiving unit 503 is further configured to receive the first data packet; wherein, the destination IP address of the first data packet is the IP address of the CE device, and the source IP address of the first data packet Is the IP address of the target network device.
  • the processing unit 502 is further configured to determine whether the first data packet is the first BFD control packet; if the first data packet is the first BFD control packet, terminate the first BFD control packet.
  • the processing unit 502 is further configured to determine a data transmission path used to transmit the second BFD control packet, and combine the first BFD session with the data used to transmit the second BFD control packet. Transmission path association.
  • the processing unit 502 is specifically configured to determine the data transmission path associated with the first BFD session as the first data transmission path for transmitting the first BFD control packet.
  • the processing unit 502 is specifically configured to associate the IP address of the CE device and the IP address of the target network device with the data transmission path used to transmit the second BFD control packet.
  • the second transceiving unit 503 is further configured to receive the first data packet; wherein, the destination IP address of the first data packet is the IP address of the CE device, and the source IP address of the first data packet Is the IP address of the target network device.
  • the processing unit 502 is further configured to determine whether the first data packet is a first BFD control packet.
  • the first transceiver unit is also used to send the first data packet to the CE device.
  • the processing unit 502 is further configured to determine a third data transmission path for transmitting the fourth BFD control packet when receiving the fourth BFD control packet from the target network device. Wherein, the fourth BFD control packet is used to indicate that the first BFD session is in the disconnected state.
  • the second transceiver unit 502 is further configured to use a fourth data transmission path other than the third data transmission path in the data transmission path group to receive and/or send a service flow belonging to the target service.
  • the data transmission path group may include, but is not limited to: PWG, VLAN transmission path group, or SVLAN transmission path group.
  • the first network device includes a first interface, and the CE device is connected to the first interface; the target service is determined according to the VLAN identifier and the identifier of the first interface.
  • an embodiment of the present application also provides a communication device 600.
  • the communication device 600 includes: a processing unit 601 configured to establish a first BFD session; wherein the session address of the first BFD session includes the IP address of the CE device and the IP address of the target network device.
  • the transceiving unit 602 is configured to send a first BFD control message to the first network device; where the first BFD control message is used to indicate that the first BFD session is in a connection establishment state, and the first BFD control message is connected through the target network device The data transmission path between the second network device and the first network device is transmitted to the first network device.
  • the processing unit 601 is further configured to perform protection switching when the target network device does not receive the third BFD control packet within a preset number of consecutive time intervals; where the third The source IP address of the BFD control message is the IP address of the CE device, and the destination IP address of the third BFD control message is the IP address of the target network device.
  • the IP routing domain further includes a fourth network device, the two third network devices are respectively connected to the fourth network device, and the target network device establishes a second BFD session with the fourth network device.
  • the transceiver unit 602 is further configured to send a fourth BFD control message to the first network device when the second BFD session is in a disconnected state, and trigger the processing unit 601 to perform protection switching; wherein, the fourth BFD control message is used In order to indicate that the first BFD session is in the disconnected state, the fourth BFD control message is transmitted to the first network device through the data transmission path between the second network device connected to the target network device and the first network device.
  • an embodiment of the present application also provides a network device 700.
  • the network device 700 may perform each step performed by the first network device/layer two device M1 in any of the methods shown in FIGS. 2 to 5, or perform the steps performed by the method shown in any of FIGS. 3 to 5 In order to avoid repetition, the steps performed by the target network device/layer three device R1 will not be described in detail here.
  • the network device 700 includes: a memory 701 for storing programs; a communication interface 702 for communicating with other devices; and a processor 703 for executing programs in the memory 701.
  • the The processor 703 is at least configured to: receive an ARP message from the CE device through the communication interface 702; wherein the ARP message includes the virtual local area network VLAN identifier and the IP address of the CE device; and determines data associated with the target service Transmission path group; wherein the target service is determined according to the VLAN identifier, and the data transmission path group includes two data transmission paths between each of the second network devices and the first network device; when When the first network device does not receive the first BFD control message from the target network device within a preset number of consecutive time intervals, it is determined that the data transmission path group is used for transmitting the first BFD control message.
  • the first data transmission path of the document wherein the target network device is one of the two third network devices, the first BFD control packet is used to indicate that the first BFD session is in a connection establishment state, and the The session address of the first BFD session includes the IP address of the CE device and the IP address of the target network device; according to the second data transmission path other than the first data transmission path in the data transmission path group, receiving And/or send a service flow belonging to the target service.
  • the processor 703 is further configured to: establish a first BFD session; wherein the session address of the first BFD session includes the IP address of the CE device and the IP address of the target network device; through the communication interface 702 Send a first BFD control message to the first network device; wherein, the first BFD control message is used to indicate that the first BFD session is in a connection establishment state, and the first BFD control message passes through the The data transmission path between the second network device connected to the target network device and the first network device is transmitted to the first network device.
  • the network device 700 shown in FIG. 7 may be a chip or a circuit.
  • the aforementioned communication interface 702 may also be a transceiver.
  • the transceiver includes a receiver and a transmitter.
  • the network device 700 may also include a bus system.
  • the processor 703, the memory 701, the receiver and the transmitter are connected through a bus system, and the processor 703 is used to execute the instructions stored in the memory 701 to control the receiver to receive signals and control the transmitter to send signals to complete any of the applications.
  • the receiver and the transmitter may be the same or different physical entities. When they are the same physical entity, they can be collectively referred to as transceivers.
  • the memory 701 may be integrated in the processor 703, or may be provided separately from the processor 703.
  • the functions of the receiver and transmitter may be implemented by a transceiver circuit or a dedicated transceiver chip.
  • the processor 703 may be implemented by a dedicated processing chip, a processing circuit, a processor, or a general-purpose chip.
  • an embodiment of the present application also provides a chip system, which includes a processor, and is configured to implement the functions of the communication device 500/communication device 600 described in any of the foregoing embodiments.
  • the chip system further includes a memory, and the memory is used to store program instructions and/or data.
  • the chip system can be composed of chips, and can also include chips and other discrete devices.
  • the disclosed system, device, and method may be implemented in other ways.
  • the device embodiments described above are illustrative.
  • 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 may be Integrate 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 technical solutions provided in this embodiment.
  • 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 above-mentioned integrated unit can be implemented in the form of hardware or software functional unit.
  • the integrated unit 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 all or 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 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, random access memory, magnetic disk or optical disk and other media that can store program codes.
  • a computer program product is provided.
  • the computer program product includes computer program code. When the computer program code runs on a computer, the computer executes any one of the first aspect or the second aspect described above. Methods.

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Abstract

本申请提供了一种保护倒换方法及装置。MAC交换域的第一网络设备可获得VLAN标识和CE设备的IP地址，并确定基于VLAN标识确定的目标业务所关联的数据传输路径组。如果第一网络设备在预设数量个连续的时间间隔内未接收到来自目标网络设备且用于指示BFD会话处于连接建立状态的BFD控制报文，用于传输BFD控制报文的数据传输路径则无法承载目标业务，利用数据传输路径组中的另一条数据传输路径传输目标业务的业务流。目标网络设备为IP路由域的两个第三网络设备中的一个，两个第三网络设备与MAC交换域中的两个第二网络设备对应连接，BFD会话的会话地址包括CE设备和目标网络设备的IP地址，数据传输路径组包括两个第二网络设备各自与第一网络设备的数据传输路径。

Description

保护倒换方法及装置
本申请要求于2020年5月7日提交中国国家知识产权局、申请号为202010378954.1、发明名称为“保护倒换方法及装置”的中国专利申请的优先权，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，尤其涉及保护倒换方法及装置。
背景技术
通信网络中，通常可以为某一项业务配置数据传输路径组。当数据传输路径组中的其中一条数据传输路径发生故障时，可将业务流切换到另一条数据传输路径进行传输。如此，可以确保该项业务的连续性。
运营商可能利用工作在数据链路层的网络设备和工作在网络层的网络设备，对通信网络进行混合组网。其中，工作在数据链路层的网络设备也被称为二层设备，二层设备可以根据其接收的数据包所包括的媒体接入控制(media access control，MAC)地址，转发其接收的数据包；工作在网络层的网络设备也可以称为三层设备，三层设备可以根据其接收的数据包所包括的互联网协议(internet protocol，IP)地址，转发其接收的数据包。也就是说，二层设备和三层设备采用不同的通信协议，对其接收的数据包进行转发处理。
通常的，二层设备和三层设备各自采用不同的方法对数据传输路径进行故障检测，二层设备和三层设备之间不能协同地进行保护倒换。
发明内容
本申请实施例中提供了一种保护倒换方法及装置，二层设备和三层设备能够协同地进行保护倒换，有利于MAC交换域和IP路由域更好地对接业务。
第一方面，提供了一种保护倒换方法，该方法应用于MAC交换域中的第一网络设备。第一网络设备与用户边缘(customer edge，CE)设备连接；MAC交换域还包括两个第二网络设备，两个第二网络设备与IP路由域中的两个第三网络设备一一对应连接。该方法包括：接收来自CE设备的地址解析协议(address resolution protocol，ARP)报文，该ARP报文中包括虚拟局域网(virtual local area network，VLAN)标识和所述CE设备的IP地址。然后，确定目标业务关联的数据传输路径组，该目标业务是根据VLAN标识确定的，数据传输路径组包括两个第二网络设备各自与第一网络设备之间的数据传输路径。接着，当第一网络设备在预设数量个连续的时间间隔内未接收到来自目标网络设备的第一双向转发检测(bidirectional forwarding detection，BFD)控制报文时，确定数据传输路径组中用于传输第一BFD控制报文的第一数据传输路径，目标网络设备为两个所述第三网络设备中的一个，第一BFD控制报文用于指示第一BFD会话处于连接建立状态，第一BFD会话的会话地址包括CE设备的IP地址和目标网络设备的IP地址。之后，利用数据传输路径组中除第一数据传输路径以外的第二数据传输路径，接收和/或发送属于所述目标业务的业务流。
换而言之，与CE设备连接的二层设备(即第一网络设备)可以接收来自CE设备的ARP报文，并从该ARP报文中获得VLAN标识和CE设备的IP地址。对于根据该VLAN标识确定的目标业务，第一网络设备可以确定目标业务关联的数据传输路径组，该数据传输线路组中包括MAC交换域所包括的其中两个二层设备(即两个第二网络设备)各自与第一网络设备之间的数据传输路径，且两个第二网络设备与IP路由域所包括的其中两个三层设备(第三网络设备)一一对应连接。其中一个第三网络设备可以作为目标网络设备，建立以CE设备的IP地址和该目标网络设备的IP地址为会话地址的第一BFD会话，并向该第一网络设备发送用于指示第一BFD会话处于连接建立状态的第一BFD控制报文。当第一网络设备在预设数量个连续的时间间隔内未接收到该第一BFD控制报文时，说明目标网络设备与第一网络设备之间的数据传输路径可能发生故障；对于属于目标业务的业务流而言，可能无法通过数据传输路径组中用于传输第一BFD控制报文的第一数据传输路径进行传输。相应的，第一网络设备即可根据数据传输路径组以及用于传输第一BFD控制报文的数据传输路径，对目标业务进行保护倒换。第一网络网络设备进行保护倒换之后，即可利用数据传输路径组中除第一数据传输路径以外的第二数据传输路径，接收和/或发送属于目标业务的数据包。
如此，CE设备连接的二层设备可以感知IP路由域中与二层设备连接的三层设备的故障，并基于其感知的故障对目标业务进行保护倒换，实现在与二层设备连接的三层设备发生故障时，MAC交换域中的二层设备和IP路由域中的三层设备协同地进行保护倒换，有利于通信网络中的IP路由域和MAC交换域更好地对接业务。
在一种可能的实施方式中，第一网络设备还可以接收来自目标网络设备的第二BFD控制报文；该第二BFD控制报文的目的IP地址为CE设备的IP地址，第二BFD控制报文的源IP地址为所述目标网络设备的IP地址。然后对第二BFD控制报文进行响应以建立第一BFD会话。而且，第一网络设备还可以终结该第二BFD控制报文，不再向第一网络设备连接的CE设备转发该第一BFD控制报文。如此，第一网络设备即可替代其连接的CE设备与目标网络设备建立第一BFD会话。
在一种可能的实施方式中，在第一网络设备完成替代其连接的CE设备与目标网络设备建立第一BFD会话之后，可以向目标网络设备发送用于指示第一BFD会话处于连接建立状态的第三BFD控制报文，以便目标网络设备通过判断其自身是否发生在预设数量个连续的时间间隔内未接收到第三BFD控制报文，确定第一网络设备与目标网络设备之间的数据传输路径是否发生故障。
在一种可能的实施方式中，在第一网络设备完成与目标网络设备建立第一BFD会话之后，第一网络设备还可以监听目的IP地址为CE设备的IP地址、源IP地址为目标网络设备的IP地址的第一数据包，然后确定该第一数据包是否为用于指示第一BFD会话处于连接建立状态的第一BFD控制报文，以便第一网络设备判断其自身是否发生在预设数量个连续的时间间隔内未接收到第一BFD控制报文。另外，第一BFD控制报文在第一网络设备处终结，不会被转发至第一网络设备连接的CE设备，避免CE设备对该第一BFD控制报文进行响应而增加CE设备的负载或造成其它问题。
在一种可能的实施方式中，在第一网络设备接收到第二BFD控制报文之后，还可以确定用于传输第二BFD控制报文的数据传输路径，并将第一BFD会话与用于传输第二BFD控制报文的数据传输路径关联。相应的，第一网络设备可以将第一BFD会话关联的数据传输 路径，确定为用于传输第一BFD控制报文的第一数据传输路径。
在一种可能的实施方式中，第一网络设备可以将CE设备的IP地址和目标网络设备的IP地址与用于传输第二BFD控制报文的数据传输路径关联，从而实现将将第一BFD会话与用于传输第二BFD控制报文的数据传输路径关联。
在一种可能的实施方式中，第一网络设备可以监听目的IP地址为所述CE设备的IP地址、源IP地址为目标网络设备的IP地址的第一数据包；然后确定该第一数据包是否为用于指示第一BFD会话处于连接建立状态的第一BFD控制报文，以便第一网络设备判断其自身是否发生在预设数量个连续的时间间隔内未接收到第一BFD控制报文。另外，第一网络设备对第一数据包进行正常的转发，不会对CE设备与目标网络设备之间建立的第一BFD会话及其它业务造成影响。
在一种可能的实施方式中，当第一网络设备接收到用于指示第一BFD会话处于连接中断状态的第四BFD控制报文时，第一网络设备还可以确定数据传输路径组中用于传输第四BFD控制报文的第三数据传输路径，并根据数据传输路径组中除第三数据传输路径以外的第四数据传输路径，接收和/或发送属于所述目标业务的业务流。如此，实现在第一网络设备无法感知第一网络设备与目标网络设备之间的数据传输路径是否发生故障的情况下，直接进行保护倒换以确保目标业务的连续型。
在一种可能的实施方式中，数据传输路径组可以包括但不限于：伪线组(pseudo wire group，PWG)、VLAN传输路径组或服务提供商虚拟局域网(service provider virtual local area network，SVLAN)传输路径组。
在一种可能的实施方式中，第一网络设备包括第一接口，CE设备与第一接口连接；目标业务是根据VLAN标识和第一接口的标识确定的。
第二方面，提供了一种保护倒换方法，有益效果可参考第一方面中的描述。该方法应用于IP路由域中的目标网络设备，目标网络设备为IP路由域所包括的两个第三网络设备中的一个，两个第三网络设备与MAC交换域中的两个第二网络设备一一对应连接；MAC交换域还包括第一网络设备，第一网络设备与用户边缘CE设备连接，两个第二网络设备各自通过不同的数据传输路径与所述第一网络设备连接。该方法包括：建立以CE设备的IP地址和目标网络设备的IP地址为会话地址的第一BFD会话；向第一网络设备发送用于指示第一BFD会话处于连接建立状态的第一BFD控制报文该第一BFD控制报文通过目标网络设备连接的第二网络设备与第一网络设备之间的数据传输路径传输至第一网络设备。
在一种可能的实施方式中，当目标网络设备在预设数量个连续的时间间隔内未接收到用于指示第一BFD会话处于连接建立状态的第三BFD控制报文时，进行保护倒换，该第三BFD控制报文的源IP地址为CE设备的IP地址，该第三BFD控制报文的目的IP地址为目标网络设备的IP地址。
在一种可能的实施方式中，IP路由域中还包括第四网络设备，两个第三网络设备各自与第四网络设备连接，目标网络设备与第四网络设备建立了第二BFD会话。目标网络设备还可以在第二BFD会话处于连接中断状态时，向第一网络设备发送用于指示第一BFD会话处于连接中断状态的第四BFD控制报文，并进行保护倒换，该第四BFD控制报文通过目标网络设备连接的第二网络设备与第一网络设备之间的数据传输路径传输至第一网络设备。
第三方面，提供了一种通信装置，有益效果可参考第一方面中的描述。该通信装置应 用于MAC交换域中的第一网络设备，更具体地说该通信装置可以是第一网络设备，也可以是部署在第一网络设备中的模块、芯片或片上系统。该第一网络设备与用户边缘CE设备连接；MAC交换域还包括两个第二网络设备，两个第二网络设备与IP路由域中的两个第三网络设备一一对应连接。该通信装置包括：第一收发单元，用于接收来自CE设备的地址解析协议ARP报文；其中，ARP报文中包括虚拟局域网VLAN标识和CE设备的IP地址。处理单元，用于确定目标业务关联的数据传输路径组；其中，目标业务是根据VLAN标识确定的，数据传输路径组包括两个第二网络设备各自与第一网络设备之间的数据传输路径；以及，当第一网络设备在预设数量个连续的时间间隔内未接收到来自目标网络设备的第一BFD控制报文时，确定数据传输路径组中用于传输第一BFD控制报文的第一数据传输路径；其中，目标网络设备为两个第三网络设备中的一个，第一BFD控制报文用于指示第一BFD会话处于连接建立状态，第一BFD会话的会话地址包括CE设备的IP地址和目标网络设备的IP地址。第二收发单元，用于利用数据传输路径组中除第一数据传输路径以外的第二数据传输路径，接收和/或发送属于目标业务的业务流。
在一种可能的实施方式中，该第二收发单元，还用于接收来自目标网络设备的第二BFD控制报文；其中，第二BFD控制报文的目的IP地址为CE设备的IP地址，第二BFD控制报文的源IP地址为目标网络设备的IP地址。该处理单元，还用于对第二BFD控制报文进行响应以建立第一BFD会话。该第二收发单元，还用于向目标网络设备发送第三BFD控制报文；其中，第三BFD控制报文用于指示第一BFD会话处于连接建立状态。
在一种可能的实施方式中，该第二收发单元，还用于接收第一数据包；其中，第一数据包的目的IP地址为CE设备的IP地址，第一数据包的源IP地址为目标网络设备的IP地址。该处理单元，还用于确定第一数据包是否是第一BFD控制报文；如果第一数据包是第一BFD控制报文，终结第一BFD控制报文。
在一种可能的实施方式中，该处理单元，还用于确定用于传输第二BFD控制报文的数据传输路径，并将第一BFD会话与用于传输第二BFD控制报文的数据传输路径关联。该处理单元，具体用于将第一BFD会话关联的数据传输路径，确定为用于传输第一BFD控制报文的第一数据传输路径。
在一种可能的实施方式中，该处理单元，具体用于将CE设备的IP地址和目标网络设备的IP地址与用于传输第二BFD控制报文的数据传输路径关联。
在一种可能的实施方式中，该第二收发单元，还用于接收第一数据包；其中，第一数据包的目的IP地址为CE设备的IP地址，第一数据包的源IP地址为目标网络设备的IP地址。该处理单元，还用于确定第一数据包是否是第一BFD控制报文。该第一收发单元，还用于向CE设备发送第一数据包。
在一种可能的实施方式中，该处理单元，还用于当接收到来自目标网络设备的第四BFD控制报文时，确定数据传输路径组中用于传输第四BFD控制报文的第三数据传输路径；其中，第四BFD控制报文用于指示第一BFD会话处于连接中断状态。该第二收发单元，还用于利用数据传输路径组中除第三数据传输路径以外的第四数据传输路径，接收和/或发送属于目标业务的业务流。
在一种可能的实施方式中，数据传输路径组可以包括但不限于：PWG、VLAN传输路径组或SVLAN传输路径组。
在一种可能的实施方式中，第一网络设备包括第一接口，CE设备与第一接口连接；目标业务是根据VLAN标识和第一接口的标识确定的。
第四方面，提供了一种通信装置，有益效果可参考第一方面中的描述。该通信装置应用于IP路由域中的目标网络设备，更具体地说该通信装置可以是目标网络设备，也可以是部署在目标网络设备中的模块、芯片或片上系统。该目标网络设备为IP路由域所包括的两个第三网络设备中的一个，两个第三网络设备与MAC交换域中的两个第二网络设备一一对应连接；MAC交换域还包括第一网络设备，第一网络设备与用户边缘CE设备连接，两个第二网络设备各自通过不同的数据传输路径与第一网络设备连接。该通信装置包括：处理单元，用于建立第一BFD会话；其中，第一BFD会话的会话地址包括CE设备的IP地址和目标网络设备的IP地址。收发单元，用于向第一网络设备发送第一BFD控制报文；其中，第一BFD控制报文用于指示第一BFD会话处于连接建立状态，第一BFD控制报文通过目标网络设备连接的第二网络设备与第一网络设备之间的数据传输路径传输至第一网络设备。
在一种可能的实施方式中，该处理单元，还用于当目标网络设备在预设数量个连续的时间间隔内未接收到第三BFD控制报文时，进行保护倒换；其中，第三BFD控制报文的源IP地址为CE设备的IP地址，第三BFD控制报文的目的IP地址为目标网络设备的IP地址。
在一种可能的实施方式中，IP路由域中还包括第四网络设备，两个第三网络设备各自与第四网络设备连接，目标网络设备与第四网络设备建立了第二BFD会话。该收发单元，还用于当第二BFD会话处于连接中断状态时，向第一网络设备发送第四BFD控制报文，并触发处理单元进行保护倒换；其中，第四BFD控制报文用于指示第一BFD会话处于连接中断状态，第四BFD控制报文通过目标网络设备连接的第二网络设备与第一网络设备之间的数据传输路径传输至第一网络设备。
第五方面，提供了一种网络设备，包括存储器和处理器，存储器中存储有可执行代码，处理器执行可执行代码时，实现第一方面或者第二方面中任一项所述的方法。
第六方面，提供了一种计算机可读存储介质，用于存储指令，当该指令被网络设备的处理器执行时，网络设备实现第一方面或者第二方面中任一项所述的方法
第七方面，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代码，当所述计算机程序代码在计算机上运行时，使得计算机执行上述第一方面或第二方面中任一项所述的方法。
第八方面，提供了一种芯片系统，该芯片系统包括处理器，用于实现上述各个方面中所述的通信装置的功能，例如，接收或处理上述第一方面/第二方面的方法中所涉及的数据和/或信息。在一种可能的设计中，所述芯片系统还包括存储器，所述存储器，用于保存程序指令和/或数据。该芯片系统可以由芯片构成，也可以包括芯片和其他分立器件。
附图说明
下面对实施例或现有技术描述中所需使用的附图作简单地介绍。
图1为本申请实施例中提供的技术方案所适用的一种业务场景的示意图。
图2为本申请实施例中提供的一种保护倒换方法的流程图。
图3为本申请实施例中二层设备与三层设备协同地进行保护倒换的过程示意图。
图4为本申请实施例中三层设备与二层设备建立BFD会话的过程示意图。
图5为本申请实施例中提供的一种通信装置的结构示意图。
图6为本申请实施例中提供的另一种通信装置的结构示意图。
图7为本申请实施例中提供的一种网络设备的结构示意图。
具体实施方式
下面将结合本申请实施例中提供的附图，对本申请实施例中提供的技术方案进行描述。
运营商可能采用二层设备和三层设备对通信网络进行混合组网。二层设备是指工作在数据链路层的网络设备，例如，交换机。二层设备接收到来自其它设备的数据包时，可以根据该数据包中包括的MAC地址，对该数据包进行转发处理。三层设备是指工作在网络层的网络设备，例如，路由器。三层设备接收到来自其它设备的数据包时，可以根据该数据包中包括的IP地址，对该数据包进行转发处理。
需要说明的是，网络设备可能同时具有二层设备和三层设备的能力。比如，部分交换机可能同时具有二层设备的能力和三层设备的能力。如果同时具有二层设备的能力和三层设备的能力，则该网络设备可能被配置为根据其接收的数据包所包括的MAC地址对数据包进行转发处理，也可能被配置为根据其接收的数据包所包括的IP地址对数据包进行转发处理。
图1为本申请实施例中提供的技术方案所适用的一种业务场景的示意图。如图1所示，通信网络包括一个或多个CE设备、MAC交换域和IP路由域。其中，MAC交换域包括多个二层设备，IP路由域包括多个三层设备。二层设备M2、二层设备M3分别和MAC交换域和IP路由域之间的数据传输路径包括：二层设备M2与三层设备R1之间的数据传输路径以及二层设备M3与三层设备R2之间的数据传输路径。当其中任意一条数据传输路径发生故障时，即可对被保护的目标业务进行保护倒换，通过另一条并未发生故障的数据传输路径传输属于该目标业务的业务流，确保该业务流所属的业务的连续性。可以理解，属于目标业务的业务流是指属于目标业务的一个或多个数据包。
本申请实施例中，二层设备M1也被称为第一网络设备；二层设备M2、二层设备M3也被称为第二网络设备；三层设备R1、三层设备R2也被称为第三网络设备；三层设备R3也被称为第四网络设备。
可以理解，第一网络设备可以配置一个或多个用于连接CE设备的接口。当第一网络设备配置多个用于连接CE设备的接口时，可连接不同的CE设备。如图1所示，二层设备M1配置了用于接口GE1和接口GE2，并通过接口GE1连接CE设备1，通过接口GE2连接CE设备2。
可以理解，第一网络设备和第二网络设备之间的数据传输路径中，可能包括一个或多个二层设备。如图1所示，二层设备M1和二层设备M2之间直接连接，但是二层设备M1与二层设备M3之间的数据传输路径中还包括二层设备M4。类似地，第三网络设备与第四网络设备之间的数据传输路径中，可以包括一个或多个三层设备。如图1所示，三层设备R1与R3直接连接，但是三层设备R2与R3之间的数据传输路径中还包括三层设备R4。
在二层设备和三层设备混合组网的通信网络中，对数据传输路径进行故障检测时，通常可以对MAC交换域和IP路由域进行分段检测。也就是说，在如图1所示的业务场景中， MAC交换域中的二层设备和IP路由域中的三层设备，可以各自采用不同的方法对数据传输路径进行故障检测。MAC交换域和IP路由域通常采用不同的保护倒换技术。比如，MAC交换域采用PW快速保护倒换(fast protection switching，FPS)技术进行保护倒换，IP路由域采用虚拟路由冗余协议(virtual router redundancy protocol，VRRP)技术进行保护倒换。这会导致两个域中的设备互不感知对方的故障，无法进行协同的保护倒换。
比如，IP路由域中的三层设备R1发生故障，导致与其连接的其它三层设备进行保护倒换时，MAC交换域中的二层设备M1无法感知三层设备R1的故障而并不会及时的进行保护倒换。如此，IP路由域中的三层设备(比如与三层设备R1连接的三层设备R2或三层设备R3)进行保护倒换之后，可能通过R2与M3之间的数据传输路径接收和/或发送属于某项业务的业务流，不再通过R1与M2之间的数据传输路径接收或发送属于该项业务的业务流。但是，由于二层设备M1无法感知三层设备R1的故障，二层设备M1未能与三层设备协同地进行保护倒换，二层设备M1可能仍然在二层设备M1与二层设备M2之间的数据传输路径上接收和/或发送属于该项业务的业务流，这就导致MAC交换域和IP路由域之间不能高效的对接业务。
为了解决上述问题，本申请实施例中至少提供了一种保护倒换方法及装置。在该方法中，与CE设备连接的二层设备(第一网络设备)接收来自CE设备的ARP报文，并从该ARP报文中获得VLAN标识和CE设备的IP地址。接着，对于根据该VLAN标识确定的目标业务，第一网络设备确定目标业务关联的数据传输路径组，该数据传输线路组中包括MAC交换域所包括的其中两个二层设备(两个第二网络设备)各自与第一网络设备之间的数据传输路径，且两个第二网络设备与IP路由域所包括的其中两个三层设备(第三网络设备)一一对应连接。之后，其中一个第三网络设备可以作为目标网络设备，建立以CE设备的IP地址和该目标网络设备的IP地址为会话地址的第一BFD会话，并向该第一网络设备发送用于指示第一BFD会话处于连接建立状态的第一BFD控制报文。当第一网络设备在预设数量个连续的时间间隔内未接收到该第一BFD控制报文时，说明目标网络设备与第一网络设备之间的数据传输路径发生故障；目标业务的业务流可能无法通过数据传输路径组中用于传输第一BFD控制报文的第一数据传输路径进行传输。第一网络设备可利用数据传输路径组中除第一数据传输路径以外的第二数据传输路径来接收和/或发送属于目标业务的数据包。如此，CE设备连接的二层设备可以感知IP路由域中与二层设备连接的三层设备的故障，并基于其感知的故障对目标业务进行保护倒换，使得MAC交换域中的二层设备可以和IP路由域中的三层设备协同地进行保护倒换，有利于通信网络中的IP路由域和MAC交换域更好地对接目标业务。
图2为本申请实施例中提供的一种保护倒换方法的流程图。如图2所示，该方法至少可以包括如下步骤。
步骤201，第一网络设备接收来自CE设备的ARP报文。
其中，该ARP报文中包括CE设备的IP地址和VLAN标识。更具体地说，该ARP报文的源IP地址为该CE设备的IP地址，该ARP报文中还可以包括VLAN标识。
步骤203，第一网络设备确定目标业务关联的数据传输路径组。
其中，目标业务是根据ARP报文中包括的VLAN标识确定的；数据传输路径组中包括两个第二网络设备各自与第一网络设备之间的数据传输路径。
步骤205，当第一网络设备在预设数量个连续的时间间隔内未接收到来自目标网络设备的第一BFD控制报文时，第一网络设备确定数据传输路径组中用于传输第一BFD控制报文的第一数据传输路径。
其中，第一BFD控制报文用于指示第一BFD会话处于连接建立状态；第一BFD会话的会话地址包括CE设备的IP地址和目标网络设备的IP地址；目标网络设备可以在其完成建立第一BFD会话之后，以相应的时间间隔周期性的向第一网络设备发送第一BFD控制报文。当第一网络设备在预设数量个连续的时间间隔内未接收到来自目标网络设备的第一BFD控制报文时，说明目标网络设备可能已经发生故障，对于属于目标业务的业务流而言，可能无法通过数据传输路径组中用于传输第一BFD控制报文的第一数据传输路径进行传输。
步骤207，第一网络设备利用数据传输路径组中除第一数据传输路径以外的第二数据传输路径，接收和/或发送属于目标业务的数据包。
根据本申请的实施例，IP路由域中用于与二层设备连接的三层设备发生故障时，IP路由域中与该三层设备连接的其它三层设备可以感知该三层设备的故障，其它三层设备可以基于其感知的故障进行保护倒换。同时，与CE设备连接的二层设备可以感知IP路由域中与二层设备连接的三层设备的故障，并基于其感知的故障进行保护倒换，最终实现二层设备与三层设备协同地进行保护倒换，有利于MAC交换域和IP路由域对接目标业务。
在一种可能的实施方式中，用户可以在实际应用场景中对用于连接CE设备的二层设备进行配置，使得该二层设备对特定的CE设备执行本申请实施例中提供的保护倒换方法。
在一些实施例中，对于二层设备中用于连接CE设备的每个接口，配置其对应的“BFD会话代理使能”功能和/或“BFD会话同步功能”，二层设备根据用户对该接口的操作，确定是否使能对该接口的BFD会话代理或BFD会话同步。
在一些实施例中，对于二层设备中用于连接CE设备的每个接口，二层设备根据来自其它通信设备的配置信息，或者根据预先设置到二层设备中的配置信息，确定是否使能对该接口的BFD会话代理或BFD会话同步。
对于二层设备中用于连接CE设备的每个接口，如果使能对该接口的BFD会话代理，则该二层设备根据该接口连接的CE设备的IP地址，取代该接口连接的CE设备与IP路由域中的三层设备建立BFD会话，根据该BFD会话完成对该三层设备的故障感知，并在感知到该三层设备可能发生故障时进行保护倒换。
以图1所示的业务场景为例，如果二层设备M1确定使能对接口GE1的BFD会话代理，二层设备M1和IP路由域中的三层设备之间即可按照如图3所示的过程协同地进行保护倒换。
在二层设备M1确定使能对接口GE1的BFD会话代理的情况下，二层设备M1可以执行步骤301，接收来自接口GE1连接的CE设备1的ARP报文。
可以理解，CE设备1是工作在网络层的三层设备，CE设备1可以向VLAN广播ARP报文，比如向VLAN广播ARP请求或ARP响应。其中，ARP报文的源IP地址为CE设备的IP地址，ARP报文中还包括该VLAN的VLAN标识。
在一些实施例中，二层设备M1可以根据访问控制列表(access control list，ACL)，对接口GE1接收的报文的格式进行匹配，以确定该报文是否为来自CE设备1的ARP报文。
如果接口GE1接收的报文为来自CE设备1的ARP报文，二层设备M1可针对该ARP报 文执行步骤302，从ARP报文中获取CE设备1的IP地址和VLAN标识。
在一些实施例中，二层设备M1可以对ARP报文进行解析处理，从ARP报文的IP头部获取ARP报文的源IP地址，ARP报文的源IP地址为CE设备1的IP地址，以及从ARP报文中获取VLAN标识。
可以理解，如果二层设备M1确定使能对接口GE2的BFD会话代理，二层设备M1还可以对接口GE2执行与上述步骤301和步骤302相似的过程。如果二层设备M1并未确定使能对接口GE2的BFD会话代理，且并未确定使能对接口GE2的BFD会话同步，则无需对接口GE2执行与上述步骤301和步骤302相似的处理过程，避免二层设备M1的负载过高。
在一些实施例中，二层设备M1还可以将用于接收ARP报文的接口的标识、ARP报文所包括的CE设备的IP地址和VLAN标识记录到属性信息表中。如此，有利于在后续过程中根据属性信息表中记载的信息，确定需要保护的目标业务及其关联的数据传输路径组，以及取代CE设备与IP路由域中的三层设备建立第一BFD会话。
示例性的，如果接口GE1的标识为GE1，接口GE1接收的ARP报文中所包括的CE设备1的IP地址为CE_IP1，ARP报文中所包括的VLAN标识为VLAN_1。二层设备M1可以维护如下表1所示的属性信息表。
表1
序号 CE设备的IP VLAN标识 接口标识
1 CE_IP1 VLAN_1 GE1
2 … … …
需要说明的是，上述表1中的序号、CE设备的IP、VLAN标识、接口标识等字段，以及前述各个字段下的字段值，仅用于辅助描述本申请实施例中提供的技术方案，在实际应用时可以将前述各个字段以及字段值替换为真实值。
接着，二层设备M1可以执行步骤303，确定目标业务关联的数据传输路径组。
其中，数据传输路径组中可以包括二层设备M1与二层设备M2之间的数据传输路径，以及包括二层设备M1与二层设备M3之间的数据传输路径。
其中，目标业务可以是根据ARP报文中所包括的VLAN标识确定的。或者，目标业务可以是根据ARP报文中所包括的VLAN标识和用于接收该ARP报文的接口确定的。
在一些实施例中，二层设备M1还可以将数据传输路径组中的一条数据传输路径配置为主用数据传输路径，将该数据传输路径组中的另一条数据传输路径配置为备用数据传输路径。利用该主用数据传输路径，接收和/或发送属于该目标业务的业务流。
在一些实施例中，依赖于二层设备M1支持的保护倒换技术，目标业务关联的数据传输路径组可以包括但不限于PWG、VLAN传输路径组或者SVLAN传输路径组。也就是说，二层设备M2、二层设备M3各自与二层设备M1之间的数据传输路径，可以包括PW、VLAN传输路径或者SVLAN传输路径。
示例性地，二层设备M1维护如上表1所示的属性信息表，且支持PW FPS。对于由VLAN标识“VLAN_1”和接口标识“GE1”确定的目标业务，二层设备M1可以为该目标业务配置其关联的PWG，PWG中可以包括二层设备M1与二层设备M2之间的PW、二层设备M1与二层设备M3之间的PW。为了方便描述，以下将二层设备M1与二层设备M2之间的PW记为PW1，将二层设备M1与二层设备M3之间的PW记为PW2。
以PW1和PW2分别配置为主用和备用PW为例，当二层设备M1接收到来自CE设备1并且属于目标业务的业务流时，将该业务流封装到PW1中，通过PW1将该业务流传输至二层设备M2，然后由二层设备M2将该业务流发送至三层设备R1，进而由三层设备R1对该业务流进行进一步的转发，比如由三层设备R1将该业务流转发至三层设备R3。
可以理解，对于来自三层设备R3并且属于目标业务的业务流，可依次通过三层设备R1、二层设备M2、二层设备M1传输至CE设备1。
IP路由域中的三层设备R1或者三层设备R2可以作为目标网络设备，建立以接口GE1所连接的CE设备1的IP地址、目标网络设备的IP地址为会话地址的第一BFD会话。以目标网络设备为三层设备R1为例，三层设备R1可以和二层设备M1相协作以完成步骤304a，建立以三层设备R1的IP地址、CE设备1的IP地址为会话地址的第一BFD会话。
图4为三层设备R1与二层设备M1建立第一BFD会话的过程示意图。其中，为例方便描述，会话状态为down表征BFD会话处于连接中断状态、会话状态为up表征BFD会话处于连接建立状态、会话状态为init表征BFD会话处于初始状态。
作为目标网络设备的三层设备R1可以首先启动第一BFD会话的状态机，通过该状态机记录第一BFD会话的会话状态，这里可以首先将该状态机记录的会话状态置为down，然后执行步骤3041，向二层设备M1发送会话状态为down的BFD控制报文。
其中，该BFD控制报文的目的IP地址为CE设备1的IP地址，该BFD控制报文的源IP地址为三层设备R1的IP地址。为了方便描述，该BFD控制报文在本申请实施例中也被称为第二BFD控制报文。
由于与三层设备R1对应连接的二层设备是M2，第二BFD控制报文首先会被发送到与三层设备R3对应连接的二层设备M2。第二BFD控制报文被二层设备M2封装到M2与M1之间的数据传输路径中，然后由二层设备M2与二层设备M1之间的数据传输路径传输至二层设备M1。
由于二层设备M1确定使能对接口GE1的BFD会话代理，当二层设备M1接收到来自IP路由域的数据包时，可以根据接口GE1所连接的CE设备1的IP地址，检测该数据包是否为待发送至CE设备1的第二BFD控制报文。可以理解，BFD控制报文具有特定的结构，二层设备M1可以对来自IP路由域的数据包的数据结构进行匹配，实现检测数据包是否为BFD控制报文，进而确定该数据包是否为待发送至CE设备1的第二BFD控制报文。
如果该数据包为待发送至CE设备1的第二BFD控制报文，则对该第二BFD控制报文进行响应以建立第一BFD会话。示例性地，二层设备M1接收到来自IP路由域的数据包时，可以查询其记录的上述表1中是否存在CE设备的IP地址与该数据包的目的IP地址相同。如果是，则确定该数据包是否是会话状态为down的BFD控制报文。接着，如果该数据包是会话状态为down的BFD控制报文，二层设备M1可以获取该第二BFD控制报文的源IP地址和目的IP地址，得到三层设备R1的IP地址和CE设备1的IP地址。然后，二层设备M1根据三层设备R1的IP地址、CE设备1的IP地址对第二BFD控制报文进行响应，完成与三层设备R1建立第一BFD会话。
具体地，二层设备M1对第二BFD控制报文进行响应，可以包括但不限于二层设备M1与三层设备R1相协作以完成如下步骤3042至步骤3048。
在步骤3042，二层设备M1将第一BFD会话的会话状态切换至init。
具体地，二层设备M1可以在接收到第二BFD控制报文时，启动第一BFD会话的状态机，通过该状态机记录第一BFD会话的会话状态，这里可以首先将该状态机记录的会话状态置为down，然后将该状态机记录的会话状态由down切换至init。
在步骤3043，二层设备M1向三层设备R1发送会话状态为init的BFD控制报文。
其中，该BFD控制报文的目的IP地址为第二BFD控制报文的三层设备R1的IP地址，源IP地址为二层设备M1从第二BFD控制报文中获取的CE设备1的IP地址。
三层设备R1在接收到来自二层设备M1且会话状态为init的BFD控制报文之后，可以执行步骤3044，将第一BFD会话的会话状态切换至init。
具体地，三层设备R1可以对第一BFD会话的状态机进行更新，将该状态机记录的会话状态由down切换至init。
在步骤3045，三层设备R1向二层设备M1发送会话状态为init的BFD控制报文。
二层设备M1可以持续监听目的IP地址为CE设备1的IP地址、源IP地址为三层设备R1的IP地址并且会话状态为init的BFD控制报文。当二层设备M1成功监听到该BFD控制报文之后，可以执行步骤3046，将第一BFD会话的会话状态切换至up。具体地，二层设备M1可以对第一BFD会话的状态机进行更新，将该状态机记录的会话状态由init切换至up。
二层设备M1将第一BFD会话的会话状态切换至up之后，二层设备M1完成建立第一BFD会话，可以执行步骤3047，向三层设备R1发送会话状态为up的BFD控制报文。其中，该BFD控制报文的源IP地址为CE设备1的IP地址，该BFD控制报文的目的IP地址为三层设备R1的IP地址。
三层设备R1接收到目的IP地址为三层设备R1的IP地址、源IP地址为CE设备1的IP地址并且会话状态为up的BFD控制报文之后，可执行步骤3048，将第一BFD会话的会话状态切换至up。
具体地，三层设备R1可以对第一BFD会话的状态机进行更新，将该状态机记录的会话状态由init切换至UP，完成建立第一BFD会话。
在一些实施例中，对于R1向CE设备1发送的BFD控制报文，二层设备M1可以在完成对该BFD控制报文的处理之后，终结该BFD控制报文。也就是说，二层设备M1可以在完成对R1向CE设备1发送的BFD控制报文的处理之后，丢弃该BFD控制报文，不再向接口GE1连接的CE设备1转发该BFD控制报文。
在本申请实施例中，三层设备R1还可以与其它三层设备建立第二BFD会话。如图3所示，三层设备R1还可以和三层设备R3相协作以完成步骤304b，建立以三层设备R1的IP地址、三层设备R3的IP地址为会话地址的第二BFD会话。其中，三层设备R1与三层设备R3建立第二BFD会话的过程，与图4所示三层设备R1与二层设备M1建立第一BFD会话的过程相似，这里不再对三层设备R1与三层设备R3建立第二BFD会话的过程进行赘述。
在二层设备M1接收到来自三层设备R1的第二BFD控制报文之后，或者在二层设备M1与三层设备R1完成建立第一BFD会话之后，二层设备M1还可以执行步骤305，确定数据传输路径组中用于传输第二BFD控制报文的数据传输路径，并将用于传输第二BFD控制报文的数据传输路径与第一BFD会话关联。
在一些实施例中，二层设备M1可以将第一BFD会话的两个会话地址与用于传输第二BFD控制报文的数据传输路径关联。更具体地说，可以将CE设备1的IP地址、三层设备R1的 IP地址与用于传输第二BFD控制报文的数据传输路径关联。
示例性地，二层设备M2与M1之间的数据传输路径为PW1；对于目的IP地址为CE设备1的IP地址、源IP地址为三层设备R1的IP地址并且会话状态为down的BFD控制报文(即第二BFD控制报文)，二层设备M1在PW1上接收到第二BFD控制报文之后，可以通过表2所述的映射关系表，将CE设备1的IP地址“CE_IP1”、三层设备R1的IP地址“R1_IP”与PW1关联，实现将第一BFD会话与用于传输第二BFD控制报文的数据传输路径关联。
表2
序号 CE设备的IP地址 三层设备的IP地址 数据传输路径
1 CE_IP1 R1_IP PW1
2 … … …
上述表2中的序号、CE设备的IP地址、三层设备的IP地址、数据传输路径等字段，以及前述各个字段下的字段值，仅用于辅助描述本申请实施例中提供的技术方案，在实际应用时可以将前述各个字段及字段值替换为真实值。
三层设备R1可以在完成建立第一BFD会话之后，向二层设备M1周期性的发送第一BFD控制报文。其中，第一BFD控制报文的源IP地址为三层设备R1的IP地址，第一BFD控制报文的目的IP地址为CE设备1的IP地址；第一BFD控制报文用于指示第一会话状态处于连接建立状态，也就是说，第一BFD控制报文所包括的会话状态为三层设备R1启动的第一BFD会话的状态机所记录的会话状态“up”。以便二层设备M1执行步骤306a，对二层设备M1与三层设备R1之间的数据传输路径进行故障检测。
在步骤306a中，二层设备M1可以持续监听目的IP地址为CE设备1的IP地址、源IP地址为三层设备R1的IP地址的第一数据包；对于二层设备M1接收的第一数据包，可以进一步确定该第一数据包是否为用于指示第一BFD会话处于连接建立状态的第一BFD控制报文。如果该第一数据包是第一BFD控制报文，处理并终结第一BFD控制报文。如果二层设备M1在预设数量个连续的时间间隔内未接收到第一BFD控制报文，二层设备M1则可确定二层设备M1与三层设备R1之间的数据传输路径可能发生故障，比如二层设备M2或三层设备R3发生故障；对于属于目标业务的业务流而言，可能无法通过数据传输路径组中用于传输第一BFD控制报文的第一数据传输路径进行传输。
相应地，为了使三层设备R1能够实现对二层设备M1与三层设备R1之间的数据传输路径的故障进行检测，二层设备M1可以在完成建立第一BFD会话之后，向三层设备R1周期性的发送第三BFD控制报文。其中，第三BFD控制报文的源IP地址为二层设备M1的IP地址，第三BFD控制报文的目的IP地址为CE设备1的IP地址；第三BFD控制报文用于指示第一会话状态处于连接建立状态。也就是说，第三BFD控制报文所包括的会话状态为二层设备M1启动的第一BFD会话的状态机所记录的会话状态“up”。以便三层设备R1执行步骤306b，对二层设备M1与三层设备R1之间的数据传输路径进行故障检测。
在步骤306b中，三层设备R1可以持续监听目的IP地址为三层设备R1的IP地址、源IP地址为CE设备1的IP地址的第二数据包；对于三层设备R1接收的第二数据包，可以进一步确定该第二数据包的是否为用于指示第一BFD会话处于连接建立状态的第三BFD控制报文。如果三层设备R1在预设数量个连续的时间间隔内未接收到第三BFD控制报文，则说明二层设备M1与三层设备R1之间的数据传输路径发生故障，比如二层设备M1或二层设备 M2发生故障；三层设备R1可能无法继续在二层设备M2与三层设备R1之间的数据传输路径上正常的接收和/或发送属于目标业务的业务流。
与步骤306a、306b相似的，三层设备R1与三层设备R3之间还可以相互收发BFD控制报文，各自对相应的数据传输路径进行故障检测。这里不再对步骤306c、306d实现对数据传输路径进行故障检测的过程进行赘述。
如果二层设备M1在步骤306a中检测到二层设备M1与三层设备R1之间的数据传输路径可能发生故障，二层设备M1即可执行步骤307，确定目标业务关联的数据传输路径组中用于传输第一BFD控制报文的数据传输路径。
在一些实施例中，二层设备M1可以将用于传输第二BFD控制报文的数据传输路径，确定为用于传输第一BFD控制报文的第一数据传输路径。
示例性地，二层设备M1可以根据第一BFD会话的会话地址，即CE设备1的IP地址和三层设备R1的IP地址查询上述表2，确定用于传输第二BFD控制报文的数据传输路径为PW1，PW1可以被确定为用于传输第一BFD控制报文的数据传输路径。
相应地，二层设备M1可以进一步执行步骤308a，根据用于传输第一BFD控制报文的数据传输路径和目标业务关联的数据传输路径组进行保护倒换。在二层设备M1进行保护倒换之后，二层设备M1可以利用数据传输路径组中除第一数据传输路径以外的第二传输路径，接收和/或发送属于目标业务的业务流。
在一些实施例中，当三层设备R1在步骤306c检测到三层设备R1与三层设备R3之间的数据传输路径发生故障时，或者三层设备R1在用户的控制下关闭第一BFD会话时，三层设备R1可以向二层设备M1发送源IP地址为三层设备R1的IP地址、目的IP地址为CE设备1的IP地址、会话状态为“admin down”或“down”的第四BFD控制报文；其中admin down表征第一BFD会话是在用户的控制下被关闭的。
对于二层设备M1而言，如果二层设备M1接收到用于指示第一BFD会话处于连接中断状态的第四BFD控制报文，二层设备M1在此时无法确定二层设备M1与三层设备R1之间的数据传输路径是否发生故障。为了确保目标业务的连续性，二层设备M1可以从数据传输路径组中确定出用于传输该第四BFD控制报文的第三数据传输路径，然后根据第三数据传输路径和数据传输路径组进行保护倒换。二层设备M1进行保护倒换之后，可通过数据传输路径组中除第三数据传输路径外的第四数据传输路径接收和/或发送属于目标业务的业务流。
需要说明的是，当三层设备R1在步骤306c中检测到三层设备R1与三层设备R3之间的数据传输路径可能发生故障时，或者三层设备R1在用户的控制下关闭第一BFD会话时，三层设备R1在完成向二层设备M1发送第四BFD控制报文之后，可以在步骤308b进行保护倒换，从而使得二层设备M1和三层设备R1协同地进行保护倒换。
需要说明的是，当三层设备R1在步骤306b中检测到二层设备M1与三层设备R1之间的数据传输路径可能发生故障时，三层设备R1可以在步骤308b进行保护倒换。
需要说明的是，当三层设备R3在步骤306d中检测到三层设备R1与三层设备R3之间的数据传输路径可能发生故障时，三层设备R3可以在步骤308c进行保护倒换。
依赖于IP路由域中各个三层设备的连接关系、发生故障的三层设备以及各三层设备所支持的保护倒换技术，在二层设备M1与三层设备R1或者三层设备R3协同地进行保护倒换之后，来自CE设备并且属于目标业务的业务流在到达IP路由域中的三层设备R2之后，可 以通过相应的数据传输路径传输至三层设备R3。
示例性地，如果三层设备R1发生故障，三层设备R3可以在步骤306d检测到三层设备R1与三层设备R3之间的数据传输路径可能发生故障，然后在步骤308c进行保护倒换之后，不再通过R1从MAC交换域接收/发送属于目标业务的业务流，而是通过三层设备R2从MAC交换域接收/发送属于目标业务的业务流。如图3所示，在二层设备M1与三层设备R3协同地进行保护倒换之后，对于来自CE设备1且属于目标业务的业务流，二层设备M1可以通过二层设备M1与二层设备M3之间的数据传输路径发送至二层设备M3，由二层设备M3将该业务流发送至对应连接的三层设备R2，进而由三层设备R2将该业务流发送至三层设备R3。
三层设备R1类似。如图3所示，在二层设备M1与三层设备R1协同地进行保护倒换之后，对于来自CE设备1且属于目标业务的业务流，二层设备M1可以通过二层设备M1与二层设备M3之间的数据传输路径发送至二层设备M3，由二层设备M3通过其与R2之间的数据传输路径将该业务流发送至三层设备R2。之后，该业务流可以被发送至三层设备R1，由三层设备R1将该业务流发送至三层设备R3；或者，由三层设备R2将该业务流直接发送至三层设备R3。
对于二层设备中用于连接CE设备的每个接口，如果使能对该接口的BFD会话同步，则该二层设备可以根据该接口连接的CE设备的IP地址，监听该接口连接的CE设备与IP路由域中的三层设备建立的BFD会话，通过对该BFD会话的监听完成对该三层设备的故障感知，并在感知到该三层设备可能发生故障时进行保护倒换。仍然以图1所示的业务场景为例，如果二层设备M1确定使能对接口GE1的BFD会话同步，二层设备M1和IP路由域中的三层设备协同地进行保护倒换的过程，与图3所示的步骤304a不同的是，三层设备R1和CE设备1，建立以三层设备R1的IP地址、CE设备1的IP地址为会话地址的第一BFD会话。
在一种可能的实施方式中，在建立该第一BFD会话的过程中，由于二层设备M1确定使能对接口GE1的BFD会话同步，当二层设备M1接收到来自IP路由域的数据包时，可以根据接口GE1所连接的CE设备1的IP地址，检测该数据包是否为待发送至CE设备1的第二BFD控制报文；如果该数据包为待发送至CE设备1的第二BFD控制报文，则启动第一BFD会话的状态机，并将该状态机的会话状态由down切换至init；而且，二层设备M1还需要将第二BFD控制报文转发至CE设备1，以便CE设备1与三层设备R1执行如图4相似的过程，完成建立第一BFD会话。
相应的，与图3所示的步骤306a不同的是，二层设备M1通过对三层设备R1和CE设备1建立的第一BFD会话进行监听，实现对二层设备M1与三层设备R1之间的数据传输路径进行故障检测。
在一种可能的实施方式中，二层设备M1可以持续监听目的IP地址为CE设备1的IP地址、源IP地址为三层设备R1的IP地址的第一数据包；对于二层设备M1接收的第一数据包，确定该第一数据包是否为用于指示第一BFD会话处于连接建立状态的第一BFD控制报文。如果该第一数据包是第一BFD控制报文，更新第一BFD会话的状态机并向CE设备1转发该第一BFD控制报文。如果二层设备M1在预设数量个连续的时间间隔内未接收到第一BFD控制报文，二层设备M1则可确定二层设备M1与三层设备R1之间的数据传输路径可能发生故障，比如二层设备M2或三层设备R3发生故障；对于属于目标业务的业务流而言，可能无法通过数据传输路径组中用于传输第一BFD控制报文的第一数据传输路径进行传输。
需要说明的是，来自CE设备1的第三BFD控制报文经二层设备M1发送至三层设备R1。相应的，与图3所示的步骤306b不同的是，三层设备R1对CE设备1与三层设备R1之间的数据传输路径进行故障检测。
在一种可能的实施方式中，如果三层设备R1在预设数量个连续的时间间隔内未接收到第三BFD控制报文，则说明CE设备1与三层设备R1之间的数据传输路径发生故障，比如CE设备1、二层设备M1或二层设备M2发生故障；三层设备R1可能无法继续在二层设备M2与三层设备R1之间的数据传输路径上正常的接收和/或发送属于目标业务的业务流。
与前述方法实施例基于相同的构思，如图5所示，本申请实施例中还提供了一种通信装置500。该通信装置500包括：第一收发单元501，用于执行图2的步骤201。处理单元502，用于执行图2的步骤203和205。第二收发单元503，用于执行图2的步骤207。相关描述请参见图2中相关步骤的描述，在此不再赘述。
在一种可能的实施方式中，该第二收发单元503，还用于接收来自目标网络设备的第二BFD控制报文；其中，第二BFD控制报文的目的IP地址为CE设备的IP地址，第二BFD控制报文的源IP地址为目标网络设备的IP地址。该处理单元502，还用于对第二BFD控制报文进行响应以建立第一BFD会话。该第二收发单元503，还用于向目标网络设备发送第三BFD控制报文；其中，第三BFD控制报文用于指示第一BFD会话处于连接建立状态。
在一种可能的实施方式中，该第二收发单元503，还用于接收第一数据包；其中，第一数据包的目的IP地址为CE设备的IP地址，第一数据包的源IP地址为目标网络设备的IP地址。该处理单元502，还用于确定第一数据包是否是第一BFD控制报文；如果第一数据包是第一BFD控制报文，终结第一BFD控制报文。
在一种可能的实施方式中，该处理单元502，还用于确定用于传输第二BFD控制报文的数据传输路径，并将第一BFD会话与用于传输第二BFD控制报文的数据传输路径关联。该处理单元502，具体用于将第一BFD会话关联的数据传输路径，确定为用于传输第一BFD控制报文的第一数据传输路径。
在一种可能的实施方式中，该处理单元502，具体用于将CE设备的IP地址和目标网络设备的IP地址与用于传输第二BFD控制报文的数据传输路径关联。
在一种可能的实施方式中，该第二收发单元503，还用于接收第一数据包；其中，第一数据包的目的IP地址为CE设备的IP地址，第一数据包的源IP地址为目标网络设备的IP地址。该处理单元502，还用于确定第一数据包是否是第一BFD控制报文。该第一收发单元，还用于向CE设备发送第一数据包。
在一种可能的实施方式中，处理单元502，还用于当接收到来自目标网络设备的第四BFD控制报文时，确定用于传输第四BFD控制报文的第三数据传输路径。其中，第四BFD控制报文用于指示第一BFD会话处于连接中断状态。第二收发单元502，还用于利用数据传输路径组中除第三数据传输路径以外的第四数据传输路径，接收和/或发送属于目标业务的业务流。
在一种可能的实施方式中，数据传输路径组可以包括但不限于：PWG、VLAN传输路径组或SVLAN传输路径组。
在一种可能的实施方式中，第一网络设备包括第一接口，CE设备与第一接口连接；目标业务是根据VLAN标识和第一接口的标识确定的。
与前述方法实施例基于相同的构思，如图6所示，本申请实施例中还提供了一种通信装置600。该通信装置600包括：处理单元601，用于建立第一BFD会话；其中，第一BFD会话的会话地址包括CE设备的IP地址和目标网络设备的IP地址。收发单元602，用于向第一网络设备发送第一BFD控制报文；其中，第一BFD控制报文用于指示第一BFD会话处于连接建立状态，第一BFD控制报文通过目标网络设备连接的第二网络设备与第一网络设备之间的数据传输路径传输至第一网络设备。
在一种可能的实施方式中，该处理单元601，还用于当目标网络设备在预设数量个连续的时间间隔内未接收到第三BFD控制报文时，进行保护倒换；其中，第三BFD控制报文的源IP地址为CE设备的IP地址，第三BFD控制报文的目的IP地址为目标网络设备的IP地址。
在一种可能的实施方式中，IP路由域中还包括第四网络设备，两个第三网络设备各自与第四网络设备连接，目标网络设备与第四网络设备建立了第二BFD会话。该收发单元602，还用于当第二BFD会话处于连接中断状态时，向第一网络设备发送第四BFD控制报文，并触发处理单元601进行保护倒换；其中，第四BFD控制报文用于指示第一BFD会话处于连接中断状态，第四BFD控制报文通过目标网络设备连接的第二网络设备与第一网络设备之间的数据传输路径传输至第一网络设备。
与前述方法实施例基于相同的构思，如图7所示，本申请实施例中还提供了一种网络设备700。应理解，网络设备700可以执行图2至图5任一所示的方法中由第一网络设备/二层设备M1执行的各个步骤，或者执行图3至图5任一所示的方法中由目标网络设备/三层设备R1执行的各个步骤，为了避免重复，此处不再详述。其中，网络设备700包括：存储器701，用于存储程序；通信接口702，用于和其他设备进行通信；处理器703，用于执行存储器701中的程序，当所述程序被执行时，所述处理器703至少用于：通过所述通信接口702接收来自CE设备的ARP报文；其中，所述ARP报文中包括虚拟局域网VLAN标识和所述CE设备的IP地址；确定目标业务关联的数据传输路径组；其中，所述目标业务是根据所述VLAN标识确定的，所述数据传输路径组包括两个所述第二网络设备各自与所述第一网络设备之间的数据传输路径；当所述第一网络设备在预设数量个连续的时间间隔内未接收到来自目标网络设备的第一BFD控制报文时，确定所述数据传输路径组中用于传输所述第一BFD控制报文的第一数据传输路径；其中，所述目标网络设备为两个所述第三网络设备中的一个，所述第一BFD控制报文用于指示第一BFD会话处于连接建立状态，所述第一BFD会话的会话地址包括所述CE设备的IP地址和所述目标网络设备的IP地址；根据所述数据传输路径组中除所述第一数据传输路径以外的第二数据传输路径，接收和/或发送属于所述目标业务的业务流。或者，处理器703还用于：建立第一BFD会话；其中，所述第一BFD会话的会话地址包括所述CE设备的IP地址和所述目标网络设备的IP地址；通过所述通信接口702向所述第一网络设备发送第一BFD控制报文；其中，所述第一BFD控制报文用于指示所述第一BFD会话处于连接建立状态，所述第一BFD控制报文通过所述目标网络设备连接的第二网络设备与所述第一网络设备之间的数据传输路径传输至所述第一网络设备。可以理解，图7所示的网络设备700可以是芯片或电路。例如可设置在网络设备700内的芯片或电路。上述通信接口702也可以是收发器。收发器包括接收器和发送器。进一步地，该网络设备700还可以包括总线系统。
其中，处理器703、存储器701、接收器和发送器通过总线系统相连，处理器703用于执行该存储器701存储的指令，以控制接收器接收信号，并控制发送器发送信号，完成本申请任意一个实施例中提供的保护倒换方法中由第一网络设备执行的步骤。其中，接收器和发送器可以为相同或不同的物理实体。为相同的物理实体时，可以统称为收发器。所述存储器701可以集成在所述处理器703中，也可以与所述处理器703分开设置。
作为一种实现方式，接收器和发送器的功能可以考虑通过收发电路或者收发专用芯片实现。处理器703可以考虑通过专用处理芯片、处理电路、处理器或者通用芯片实现。相应的，本申请实施例中还提供了一种芯片系统，该芯片系统包括处理器，用于实现上述任一实施例中所述的通信装置500/通信装置600的功能。在一种可能的设计中，所述芯片系统还包括存储器，所述存储器，用于保存程序指令和/或数据。该芯片系统可以由芯片构成，也可以包括芯片和其他分立器件。
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实施例的范围。
本申请提供的不同实施例可以相互结合。在本申请所提供的实施例中，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中提供的技术方案的目的。
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。上述集成的单元既可以采用硬件的形式实现，也可以采用软件功能单元的形式实现。
所述集成的单元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全部或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、随机存取存储器、磁盘或者光盘等各种可以存储程序代码的介质。相应的，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代码，当所述计算机程序代码在计算机上运行时，使得计算机执行上述第一方面或第二方面中任一项所述的方法。
以上仅为本申请实施例的具体实施方式，但本申请实施例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实施例揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请实施例的保护范围之内。在本申请的各个实施例中，如果没有特殊说明以及逻辑冲突，不同的实施例的术语和/或描述具有一致性、且可以相互引用，不同的实施例中的技术特征根据其内在的逻辑关系可以组合形成新的实施例。
本申请中，“和/或”，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的情况，其中A、B可以是单数或者复数。在本申请的文字描述中，字符“/”，一般表示前后关联对象是一种“或”的关系；在本申请的公式中，字符“/”，表示前后关联对象是一种“相除”的关系。
可以理解的是，在本申请的实施例中涉及的各种数字编号是为描述方便进行的区分，并不用来限制本申请的实施例的范围。上述各过程的序号的大小并不意味着执行顺序的先后，各过程的执行顺序应以其功能和内在逻辑确定。
最后需要说明的是，以上实施例仅用以说明本申请的技术方案，而未对其限制；尽管参照前述实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解，依然可以对前述各个实施例中所提供的技术方案进行修改，或者对其中部分技术特征进行等同替换，而这些修改或替换，并不使相应技术方案的本质脱离本申请各个实施例中所提供技术方案的精神和范围。

Claims (21)

  1. 一种保护倒换方法，其特征在于，应用于媒体接入控制MAC交换域中的第一网络设备，所述第一网络设备与用户边缘CE设备连接；所述MAC交换域还包括两个第二网络设备，两个所述第二网络设备与互联网协议IP路由域中的两个第三网络设备一一对应连接；所述方法包括：
    接收来自所述CE设备的地址解析协议ARP报文；其中，所述ARP报文中包括虚拟局域网VLAN标识和所述CE设备的IP地址；
    确定目标业务关联的数据传输路径组；其中，所述目标业务是根据所述VLAN标识确定的，所述数据传输路径组包括两个所述第二网络设备各自与所述第一网络设备之间的数据传输路径；
    当所述第一网络设备在预设数量个连续的时间间隔内未接收到来自目标网络设备的第一双向转发检测BFD控制报文时，确定所述数据传输路径组中用于传输所述第一BFD控制报文的第一数据传输路径；其中，所述目标网络设备为两个所述第三网络设备中的一个，所述第一BFD控制报文用于指示第一BFD会话处于连接建立状态，所述第一BFD会话的会话地址包括所述CE设备的IP地址和所述目标网络设备的IP地址；
    利用所述数据传输路径组中除所述第一数据传输路径以外的第二数据传输路径，接收和/或发送属于所述目标业务的业务流。
  2. 根据权利要求1所述的方法，其特征在于，
    在所述当所述第一网络设备在预设数量个连续的时间间隔内未接收到来自目标网络设备的第一BFD控制报文时，确定所述数据传输路径组中用于传输所述第一BFD控制报文的第一数据传输路径之前，所述方法还包括：
    接收来自所述目标网络设备的第二BFD控制报文；其中，所述第二BFD控制报文的目的IP地址为所述CE设备的IP地址，所述第二BFD控制报文的源IP地址为所述目标网络设备的IP地址；
    对所述第二BFD控制报文进行响应以建立所述第一BFD会话；向所述目标网络设备发送第三BFD控制报文；其中，所述第三BFD控制报文用于指示所述第一BFD会话处于连接建立状态。
  3. 根据权利要求2所述的方法，其特征在于，
    在所述当所述第一网络设备在预设数量个连续的时间间隔内未接收到来自目标网络设备的第一BFD控制报文时，确定所述数据传输路径组中用于传输所述第一BFD控制报文的第一数据传输路径之前，所述方法还包括：
    接收第一数据包；其中，所述第一数据包的目的IP地址为所述CE设备的IP地址，所述第一数据包的源IP地址为所述目标网络设备的IP地址；
    确定所述第一数据包是否是所述第一BFD控制报文；
    如果所述第一数据包是所述第一BFD控制报文，终结所述第一BFD控制报文。
  4. 根据权利要求2所述的方法，其特征在于，
    在所述当所述第一网络设备在预设数量个连续的时间间隔内未接收到来自目标网络设备的第一BFD控制报文时，确定所述数据传输路径组中用于传输所述第一BFD控制报文的第一数据传输路径之前，所述方法还包括：
    确定用于传输所述第二BFD控制报文的数据传输路径，并将所述第一BFD会话与用于传输所述第二BFD控制报文的数据传输路径关联；
    所述确定所述数据传输路径组中用于传输所述第一BFD控制报文的第一数据传输路径，包括：将所述第一BFD会话关联的数据传输路径，确定为用于传输所述第一BFD控制报文的第一数据传输路径。
  5. 根据权利要求4所述的方法，其特征在于，
    所述将所述第一BFD会话与用于传输所述第二BFD控制报文的数据传输路径关联，包括：
    将所述CE设备的IP地址和所述目标网络设备的IP地址与用于传输所述第二BFD控制报文的数据传输路径关联。
  6. 根据权利要求1所述的方法，其特征在于，
    在所述当所述第一网络设备在预设数量个连续的时间间隔内未接收到来自目标网络设备的第一BFD控制报文时，确定所述数据传输路径组中用于传输所述第一BFD控制报文的第一数据传输路径之前，所述方法还包括：
    接收第一数据包；其中，所述第一数据包的目的IP地址为所述CE设备的IP地址，所述第一数据包的源IP地址为所述目标网络设备的IP地址；
    向所述CE设备发送所述第一数据包；以及，
    确定所述第一数据包是否是所述第一BFD控制报文。
  7. 根据权利要求1至6中任一所述的方法，其特征在于，所述方法还包括：
    当接收到来自所述目标网络设备的第四BFD控制报文时，确定所述数据传输路径组中用于传输所述第四BFD控制报文的第三数据传输路径；其中，所述第四BFD控制报文用于指示所述第一BFD会话处于连接中断状态；
    利用所述数据传输路径组中除所述第三数据传输路径以外的第四数据传输路径，接收和/或发送属于所述目标业务的业务流。
  8. 根据权利要求1至6中任一所述的方法，其特征在于，所述数据传输路径组包括：伪线组PWG、VLAN传输路径组或服务提供商虚拟局域网SVLAN传输路径组。
  9. 根据权利要求1至6中任一所述的方法，其特征在于，
    所述第一网络设备包括第一接口，所述CE设备与所述第一接口连接；
    所述目标业务是根据所述VLAN标识和所述第一接口的标识确定的。
  10. 一种保护倒换方法，其特征在于，应用于互联网协议IP路由域中的目标网络设备，所述目标网络设备为所述IP路由域所包括的两个第三网络设备中的一个，两个所述第三网络设备与媒体接入控制MAC交换域中的两个第二网络设备一一对应连接；所述MAC交换域还包括第一网络设备，所述第一网络设备与用户边缘CE设备连接，两个所述第二网络设备各自通过不同的数据传输路径与所述第一网络设备连接；所述方法包括：
    建立第一双向转发检测BFD会话；其中，所述第一BFD会话的会话地址包括所述CE设备的IP地址和所述目标网络设备的IP地址；
    向所述第一网络设备发送第一BFD控制报文；其中，所述第一BFD控制报文用于指示所述第一BFD会话处于连接建立状态，所述第一BFD控制报文通过所述目标网络设备连接的第二网络设备与所述第一网络设备之间的数据传输路径传输至所述第一网络设备。
  11. 根据权利要求10所述的方法，其特征在于，所述方法还包括：
    当所述目标网络设备在预设数量个连续的时间间隔内未接收到第三BFD控制报文时，进行保护倒换；其中，所述第三BFD控制报文的源IP地址为所述CE设备的IP地址，所述第三BFD控制报文的目的IP地址为所述目标网络设备的IP地址。
  12. 根据权利要求10或11所述的方法，其特征在于，
    所述IP路由域中还包括第四网络设备，两个所述第三网络设备各自与所述第四网络设备连接，所述目标网络设备与所述第四网络设备建立了第二BFD会话；
    所述方法还包括：
    当所述第二BFD会话处于连接中断状态时，向所述第一网络设备发送第四BFD控制报文，并进行保护倒换；其中，所述第四BFD控制报文用于指示所述第一BFD会话处于连接中断状态，所述第四BFD控制报文通过所述目标网络设备连接的第二网络设备与所述第一网络设备之间的数据传输路径传输至所述第一网络设备。
  13. 一种通信装置，其特征在于，应用于媒体接入控制MAC交换域中的第一网络设备，所述第一网络设备与用户边缘CE设备连接；所述MAC交换域还包括两个第二网络设备，两个所述第二网络设备与互联网协议IP路由域中的两个第三网络设备一一对应连接；所述通信装置包括：
    第一收发单元，用于接收来自所述CE设备的地址解析协议ARP报文；其中，所述ARP报文中包括虚拟局域网VLAN标识和所述CE设备的IP地址；
    处理单元，用于确定目标业务关联的数据传输路径组；其中，所述目标业务是根据所述VLAN标识确定的，所述数据传输路径组包括两个所述第二网络设备各自与所述第一网络设备之间的数据传输路径；以及，当所述第一网络设备在预设数量个连续的时间间隔内未接收到来自目标网络设备的第一双向转发检测BFD控制报文时，确定所述数据传输路径组中用于传输所述第一BFD控制报文的第一数据传输路径；其中，所述目标网络设备为两个所述第三网络设备中的一个，所述第一BFD控制报文用于指示第一BFD会话处于连接建立状态，所述第一BFD会话的会话地址包括所述CE设备的IP地址和所述目标网络设备的IP地址；
    第二收发单元，用于利用所述数据传输路径组中除所述第一数据传输路径以外的第二数据传输路径，接收和/或发送属于所述目标业务的业务流。
  14. 根据权利要求13所述的通信装置，其特征在于，
    所述第二收发单元，还用于接收来自所述目标网络设备的第二BFD控制报文；其中，所述第二BFD控制报文的目的IP地址为所述CE设备的IP地址，所述第二BFD控制报文的源IP地址为所述目标网络设备的IP地址；
    所述处理单元，还用于对所述第二BFD控制报文进行响应以建立所述第一BFD会话；所述第二收发单元，还用于向所述目标网络设备发送第三BFD控制报文；其中，所述第三BFD控制报文用于指示所述第一BFD会话处于连接建立状态。
  15. 根据权利要求14所述的通信装置，其特征在于，
    所述第二收发单元，还用于接收第一数据包；其中，所述第一数据包的目的IP地址为所述CE设备的IP地址，所述第一数据包的源IP地址为所述目标网络设备的IP地址；
    所述处理单元，还用于确定所述第一数据包是否是所述第一BFD控制报文；如果所述第一数据包是所述第一BFD控制报文，处理并终结所述第一BFD控制报文。
  16. 根据权利要求14所述的通信装置，其特征在于，
    所述处理单元，还用于确定用于传输所述第二BFD控制报文的数据传输路径，并将所述第一BFD会话与用于传输所述第二BFD控制报文的数据传输路径关联；
    所述处理单元，具体用于将所述第一BFD会话关联的数据传输路径，确定为用于传输所述第一BFD控制报文的第一数据传输路径。
  17. 根据权利要求16所述的通信装置，其特征在于，
    所述处理单元，具体用于将所述CE设备的IP地址和所述目标网络设备的IP地址与用于 传输所述第二BFD控制报文的数据传输路径关联。
  18. 根据权利要求13所述的通信装置，其特征在于，
    所述第二收发单元，还用于接收第一数据包；其中，所述第一数据包的目的IP地址为所述CE设备的IP地址，所述第一数据包的源IP地址为所述目标网络设备的IP地址；
    所述第一收发单元，还用于向所述CE设备发送所述第一数据包；以及，
    所述处理单元，还用于确定所述第一数据包是否是所述第一BFD控制报文。
  19. 根据权利要求13至18中任一所述的通信装置，其特征在于，
    所述处理单元，还用于当接收到来自所述目标网络设备的第四BFD控制报文时，确定所述数据传输路径组中用于传输所述第四BFD控制报文的第三数据传输路径；其中，所述第四BFD控制报文用于指示所述第一BFD会话处于连接中断状态；
    所述第二收发单元，还用于利用所述数据传输路径组中除所述第三数据传输路径以外的第四数据传输路径，接收和/或发送属于所述目标业务的业务流。
  20. 根据权利要求13至18中任一所述的通信装置，其特征在于，
    所述数据传输路径组包括：伪线组PWG、VLAN传输路径组或服务提供商虚拟局域网SVLAN传输路径组。
  21. 根据权利要求13至18中任一项或所述的通信装置，其特征在于，
    所述第一网络设备包括第一接口，所述CE设备与所述第一接口连接；
    所述目标业务是根据所述VLAN标识和所述第一接口的标识确定的。
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