WO2017063717A1 - Method and apparatus for network communication over an interface - Google Patents

Method and apparatus for network communication over an interface Download PDF

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Publication number
WO2017063717A1
WO2017063717A1 PCT/EP2015/074045 EP2015074045W WO2017063717A1 WO 2017063717 A1 WO2017063717 A1 WO 2017063717A1 EP 2015074045 W EP2015074045 W EP 2015074045W WO 2017063717 A1 WO2017063717 A1 WO 2017063717A1
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WIPO (PCT)
Prior art keywords
node
transport flow
mtn
communication network
transport
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PCT/EP2015/074045
Other languages
French (fr)
Inventor
Giovanni Fiaschi
Anton Smith
Balázs VARGA
Géza GAÁL
János Szabó
Shahryar KHAN
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Telefonaktiebolaget Lm Ericsson (Publ)
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Priority to PCT/EP2015/074045 priority Critical patent/WO2017063717A1/en
Publication of WO2017063717A1 publication Critical patent/WO2017063717A1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W76/00—Connection management
    • H04W76/10—Connection setup
    • H04W76/12—Setup of transport tunnels
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/1066—Session management
    • H04L65/1069—Session establishment or de-establishment
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/60—Network streaming of media packets
    • H04L65/75—Media network packet handling
    • H04L65/765—Media network packet handling intermediate
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/80—Responding to QoS

Definitions

  • the present invention relates to methods performed in a network controller of a Mobile Transport Network (MTN), a node of a communication network and a node of an MTN.
  • MTN Mobile Transport Network
  • the present invention also relates to a computer program product configured, when run on a computer, to carry out methods performed in an MTN network controller, communication network node and MTN node.
  • MTN Mobile Transport Network
  • MH Mobile Backhaul Network
  • IP TNL IP packet transport service
  • Examples of interfaces implementing the GTPv1 -U protocol are set out in TS 29.281 and some of these interfaces are illustrated in Figure 1 , which shows an example LTE Radio and Core Network, taken from 3GPP TS 23.401 .
  • Example interfaces include, in 2G networks the Gn and Gp interfaces of the General Packet Radio Service (GPRS), in 3G networks the lu, Gn and Gp interfaces of the UMTS system, and in 4G and 5G networks the S1 -U, X2, S4, S5, S8 and S12 interfaces of the Evolved Packet System (EPS).
  • GPRS General Packet Radio Service
  • S1 -U interface a typical example of interfaces implementing the GTPvl - U protocol.
  • the S1 -U interface is illustrated in Figure 1 between the eNodeBs of the E- UTRAN and the Serving Gateway (SGW) core node.
  • the S1 -U interface transports flows for 4G networks and will also in the future transport flows in 5G networks.
  • Figure 2 illustrates the protocol stack of the GTPv1 -U protocol used to implement the S1 -U interface between an eNodeB and the SGW.
  • the GTPv1 -U protocol stack multiplexes several user tunnels onto the same S1 -U interface.
  • the GTP protocol itself is in turn carried over UDP packets, with common practice being to use a single pair of UDP source and destination ports for a given GTP tunnel in a radio base station.
  • the UDP is in turn carried by IP packets.
  • the MTN implementing interfaces between RAN and core network nodes is typically deployed to include a degree of redundancy in its resources, in order to manage periods of very high traffic load or temporary unavailability of some part of the MTN, for example owing to malfunction or maintenance.
  • an MTN is usually equipped with the means to provide different levels of quality of service to traffic flowing through the MTN.
  • the provision of redundant resources in the MTN may mean that traffic carried by the MTN may follow a variety of different paths to its destination, the paths having different characteristics such as delay, delay variation, packet loss probability etc. Traffic may also experience service variations over time, as one or more paths become subject to congestion or other factors affecting the transport service provided by the MTN.
  • QoS Quality of Service
  • a method performed in a network controller of a Mobile Transport Network (MTN) the MTN providing a GPRS Tunnelling Protocol (GTP) based interface between nodes of a communication network.
  • the method comprises defining a transport flow within the MTN, the transport flow comprising at least one specified transport resource in the MTN, associating an identifier with the defined transport flow, and communicating the identifier and at least one characteristic of the transport flow to a node of the communication network.
  • MTN Mobile Transport Network
  • GTP GPRS Tunnelling Protocol
  • the network controller carries out network control functions for the Mobile Transport Network, and may be implemented as a distributed control plane or may a Software Defined Network (SDN) controller.
  • transport resources which may be specified in a defined transport flow may include:
  • MPLS Multi Protocol Label Switching
  • LSP Label Switched Path
  • IP tunnel for example Generic Routing Encapsulation (GRE) or IPsec
  • GRE Generic Routing Encapsulation
  • IPsec IPsec
  • SDH Synchronous Digital Hierarchy
  • ATM Asynchronous Transfer Mode
  • a ring forwarding direction (clockwise, anti-clockwise)
  • the communication network may comprise a Long Term Evolution, LTE, network
  • the interface may comprise an S1 -U interface.
  • the interface may for example be implemented with GTPv1 -U, specified in TS29.281 .
  • the identifier may comprise a User Datagram Protocol (UDP) port number.
  • the UDP port number may for example be a source port number.
  • communicating the identifier and at least one characteristic of the transport flow to a node of the communication network may comprise sending a message over an interface to the node of the communication network.
  • the interface to the node of the communication network, over which the message is sent may comprise a GTP based interface.
  • the message may be a GTPv2-C protocol message, GTPv2-C being specified in TS29.274.
  • the characteristic of the transport flow may comprise at least one of: delay, delay variation, packet loss probability, available bandwidth, congestion status.
  • the method may further comprise detecting a change in the at least one characteristic of the transport flow, and communicating the changed characteristic to the node in the communication network.
  • the transport flow may further comprise at least one service provided to traffic allocated to the transport flow.
  • the service provided to traffic allocated to the transport flow may comprise at least one of: a best effort service, a guaranteed performance service, and/or a reserved bandwidth service.
  • the method may further comprise communicating the service provided to traffic allocated to the transport flow to the node of the communication network.
  • the method may further comprise updating the service provided to traffic allocated to the transport flow, and communicating the updated service to the node of the communication network.
  • the method may further comprise receiving a request from a node of the communication network to amend at least one characteristic of the transport flow or at least one service provided to traffic allocated to the transport flow, and amending the transport flow to provide the requested characteristic or service.
  • the interface provided by the MTN may be between a cellular Radio Access Network, RAN, node and a core network node.
  • RAN Radio Access Network
  • Examples of such interfaces may include, in 2G networks the Gn and Gp interfaces of the General Packet Radio Service (GPRS), in 3G networks the lu, Gn and Gp interfaces of the UMTS system, and in 4G and 5G networks the S1 -U, X2, S4, S5, S8 and S12 interfaces of the Evolved Packet System (EPS).
  • GPRS General Packet Radio Service
  • 3G networks the lu, Gn and Gp interfaces of the UMTS system
  • 4G and 5G networks the S1 -U, X2, S4, S5, S8 and S12 interfaces of the Evolved Packet System (EPS).
  • EPS Evolved Packet System
  • the node in the communication network may comprise a core network node.
  • a method performed by a node in a communication network, the node being connected to another node of the communication network via a GPRS Tunnelling Protocol (GTP) based interface provided by a Mobile Transport Network (MTN).
  • the method comprises receiving an identifier and at least one characteristic of a transport flow from a network controller of the MTN, the transport flow comprising at least one specified transport resource in the MTN, selecting a user data packet for transmission to the other node, selecting a transport flow for the user data packet, including the identifier of the selected transport flow in a header of the user data packet, and forwarding the user data packet to the interface for transmission to the other node.
  • GTP GPRS Tunnelling Protocol
  • MTN Mobile Transport Network
  • Examples of communication network nodes which may carry out the method include an eNodeB, Serving Gateway (SGW), Packet Data Network Gateway (PGW), Radio Network Controller (RNC), Serving GPRS Support Node (SGSN), Mobile Switching Centre (MSC), Gateway GPRS Support Node (GGSN) etc.
  • SGW Serving Gateway
  • PGW Packet Data Network Gateway
  • RNC Radio Network Controller
  • SGSN Serving GPRS Support Node
  • MSC Mobile Switching Centre
  • GGSN Gateway GPRS Support Node
  • the communication network may comprise a Long Term Evolution (LTE) network and the interface may comprise an S1 -U interface.
  • LTE Long Term Evolution
  • receiving the identifier and at least one characteristic of the transport flow from a network controller of the MTN may comprise receiving a message over an interface from the network controller of the MTN.
  • the interface from the network controller of the MTN, over which the message is received may comprise a GTP based interface.
  • the message may be a GTPv2-C protocol message.
  • the identifier may comprises a User Datagram Protocol (UDP) port number and including the identifier of the selected transport flow in a header of the user data packet may comprise writing the UDP port number of the selected transport flow into a UDP port field of a UDP header of the user data packet.
  • the UDP port field may for example be a UDP source port field.
  • selecting a transport flow for the user data packet may comprise selecting a transport flow having a characteristic compatible with a quality of service requirement for the user data packet.
  • a method performed by a node in a Mobile Transport Network (MTN), the MTN providing a GPRS Tunnelling Protocol (GTP) based interface between first and second nodes of a communication network.
  • the method comprises receiving a user data packet from a first network node for transmission over the interface to the second network node, extracting, from a header of the user data packet, a transport flow identifier for the user data packet, the transport flow comprising at least one specified transport resource in the MTN, and processing the user data packet onto the identified transport flow.
  • the communication network may comprise a Long Term Evolution (LTE) network and the interface may comprise an S1 -U interface.
  • LTE Long Term Evolution
  • the identifier may comprises a User Datagram Protocol (UDP) port number and extracting the identifier of the transport flow from a header of the user data packet may comprises reading a UDP port number from the UDP port field of a UDP header of the user data packet.
  • the UDP port field may for example be a UDP source port field.
  • a computer program configured when run on a computer, to carry out a method according to any one of the preceding aspects of the present invention.
  • a computer program product comprising computer readable material having stored thereon a computer program according to the preceding aspect of the present invention.
  • a network controller of a Mobile Transport Network the MTN providing a GPRS Tunnelling Protocol (GTP) based interface between nodes of a communication network.
  • the network controller comprises a transport flow unit for defining a transport flow within the MTN, the transport flow comprising at least one specified transport resource in the MTN, an identifier unit for associating an identifier with the defined transport flow, and a transmission unit for communicating the identifier and at least one characteristic of the transport flow to a node of the communication network.
  • the network controller carries out network control functions for the Mobile Transport Network, and may be implemented as a distributed control plane or may a Software Defined Network (SDN) controller.
  • the communication network may comprise a Long Term Evolution (LTE) network and the interface may comprise an S1 -U interface.
  • LTE Long Term Evolution
  • the identifier may comprise a User Datagram Protocol (UDP) port number, which may be a UDP source port number.
  • the transmission unit may be for sending a message over an interface to the node of the communication network.
  • UDP User Datagram Protocol
  • the interface to the node of the communication network, over which the message is sent may comprise a GTP based interface.
  • the message may be a GTPv2-C protocol message.
  • the network controller may further comprise a detecting unit for detecting a change in the at least one characteristic of the transport flow, and the transmission unit may be for communicating the changed characteristic to the node in the communication network.
  • the transport flow may further comprise at least one service provided to traffic allocated to the transport flow.
  • the transmission unit may be for communicating the service provided to traffic allocated to the transport flow to the node of the communication network.
  • the network controller may further comprise an updating unit for updating the service provided to traffic allocated to the transport flow, and the transmission unit may be for communicating the updated service to the node of the communication network.
  • the network controller may further comprise a receiving unit for receiving a request from a node of the communication network to amend at least one characteristic of the transport flow or at least one service provided to traffic allocated to the transport flow, and the transport flow unit may be for amending the transport flow to provide the requested characteristic or service.
  • a communication network node the node being connected to another node of the communication network via a GPRS Tunnelling Protocol (GTP) based interface provided by a Mobile Transport Network (MTN).
  • GTP GPRS Tunnelling Protocol
  • MTN Mobile Transport Network
  • the node comprises a receiving unit for receiving an identifier and at least one characteristic of a transport flow from a network controller of the MTN, the transport flow comprising at least one specified transport resource in the MTN, and a user data packet unit for selecting a user data packet for transmission to the other node.
  • GTP GPRS Tunnelling Protocol
  • MTN Mobile Transport Network
  • the node further comprises a transport flow unit for selecting a transport flow for the user data packet, a header unit for including the identifier of the selected transport flow in a header of the user data packet, and a transmission unit for forwarding the user data packet to the interface for transmission to the other node.
  • the communication network may comprise a Long Term Evolution (LTE) network and the interface may comprise an S1 -U interface.
  • LTE Long Term Evolution
  • the receiving unit may be for receiving the identifier and at least one characteristic of the transport flow from a network controller of the MTN by receiving a message over an interface from the network controller of the MTN.
  • the interface from the network controller of the MTN, over which the message is received by the receiving unit may comprise a GTP based interface.
  • the message may be a GTPv2-C protocol message.
  • the identifier may comprise a User Datagram Protocol (UDP) port number and the header unit may be for writing the UDP port number of the selected transport flow into a UDP port field of a UDP header of the user data packet.
  • the UDP port number may for example be a UDP source port number.
  • the transport flow unit may be for selecting a transport flow having a characteristic compatible with a quality of service requirement for the user data packet.
  • a Mobile Transport Network (MTN) node the MTN providing a GPRS Tunnelling Protocol (GTP) based interface between first and second nodes of a communication network.
  • the MTN node comprises a receiving unit for receiving a user data packet from a first network node for transmission over the interface to the second network node, a transport flow unit for extracting, from a header of the user data packet, a transport flow identifier for the user data packet, the transport flow comprising at least one specified transport resource in the MTN, and a processing unit for processing the user data packet onto the identified transport flow.
  • the communication network may comprise a Long Term Evolution (LTE) network and the interface may comprise an S1 -U interface.
  • LTE Long Term Evolution
  • the identifier may comprises a User Datagram Protocol (UDP) port number and the transport flow unit may be for reading a UDP port number from the UDP port field of a UDP header of the user data packet.
  • the UDP port field may be a UDP source port field.
  • a network controller of a Mobile Transport Network MTN
  • the MTN providing a GPRS Tunnelling Protocol (GTP) based interface between nodes of a communication network.
  • GTP GPRS Tunnelling Protocol
  • the network controller comprises a processor and a memory, the memory containing instructions executable by the processor such that the network controller is operable to define a transport flow within the MTN, the transport flow comprising at least one specified transport resource in the MTN, associate an identifier with the defined transport flow, and communicate the identifier and at least one characteristic of the transport flow to a node of the communication network.
  • the network controller may carry out network control functions for the Mobile Transport Network.
  • the network controller may be implemented as a distributed control plane.
  • the network controller may comprise a Software Defined Network (SDN) controller.
  • SDN Software Defined Network
  • the communication network may comprise a Long Term Evolution (LTE) network and the interface may comprise an S1 -U interface.
  • LTE Long Term Evolution
  • the identifier may comprises a User Datagram Protocol (UDP) port number, and may comprise a UDP source port number.
  • UDP User Datagram Protocol
  • the network controller may be further operable to send a message over a GTP based interface to the node of the communication network.
  • the network controller may be further operable to detect a change in the at least one characteristic of the transport flow, and communicate the changed characteristic to the node in the communication network.
  • the transport flow may further comprise at least one service provided to traffic allocated to the transport flow, and the network controller may be further operable to communicate the service provided to traffic allocated to the transport flow to the node of the communication network.
  • the network controller may be further operable to update the service provided to traffic allocated to the transport flow, and communicate the updated service to the node of the communication network.
  • the network controller may be further operable to receive a request from a node of the communication network to amend at least one characteristic of the transport flow or at least one service provided to traffic allocated to the transport flow, and amend the transport flow to provide the requested characteristic or service.
  • a communication network node the node being connected to another node of the communication network via a GPRS Tunnelling Protocol (GTP) based interface provided by a Mobile Transport Network (MTN).
  • GTP GPRS Tunnelling Protocol
  • MTN Mobile Transport Network
  • the node comprises a processor and a memory, the memory containing instructions executable by the processor such that the node is operable to receive an identifier and at least one characteristic of a transport flow from a network controller of the MTN, the transport flow comprising at least one specified transport resource in the MTN, and select a user data packet for transmission to the other node.
  • the node is also operable to select a transport flow for the user data packet, include the identifier of the selected transport flow in a header of the user data packet, and forward the user data packet to the interface for transmission to the other node.
  • the communication network may comprise a Long Term Evolution, LTE, network and the interface may comprise an S1 -U interface.
  • the identifier may comprises a User Datagram Protocol (UDP) port number and the node may be further operable to write the UDP port number of the selected transport flow into a UDP port field of a UDP header of the user data packet, which may be a source port field of the UDP header.
  • UDP User Datagram Protocol
  • the node may be further operable to select a transport flow having a characteristic compatible with a quality of service requirement for the user data packet.
  • MTN Mobile Transport Network
  • GTP GPRS Tunnelling Protocol
  • the MTN node comprises a processor and a memory, the memory containing instructions executable by the processor such that the MTN node is operable to receive a user data packet from a first network node for transmission over the interface to the second network node, extract, from a header of the user data packet, a transport flow identifier for the user data packet, the transport flow comprising at least one specified transport resource in the MTN, and process the user data packet onto the identified transport flow.
  • the communication network may comprise a Long Term Evolution, LTE, network and the interface may comprise an S1 -U interface.
  • LTE Long Term Evolution
  • the interface may comprise an S1 -U interface.
  • the identifier may comprises a User Datagram Protocol (UDP) port number and the MTN node may be further operable to read a UDP port number of from the UDP port field of a UDP header of the user data packet.
  • the UDP port field may be a UDP source port field.
  • Figure 1 illustrates an example LTE Radio and Core Network
  • Figure 2 illustrates the protocol stack of the GTPv1 -U protocol used to implement an S1 -U interface
  • Figure 3 is a flow chart illustrating process steps in a method performed in a network controller of an MTN
  • Figure 4 is a flow chart illustrating process steps in another example of method performed in a network controller of an MTN
  • Figure 5 is a flow chart illustrating process steps in a method performed in a communication network node
  • Figure 6 is a flow chart illustrating process steps in a method performed in an MTN node
  • Figure 7 is a block diagram illustrating functional units in an MTN network controller
  • Figure 8 is a block diagram illustrating functional units in a communication network node
  • Figure 9 is a is a block diagram illustrating functional units in an MTN node
  • Figure 10 is a block diagram illustrating functional units in another example of MTN network controller
  • Figure 1 1 is a block diagram illustrating functional units in another example of communication network node.
  • Figure 12 is a block diagram illustrating functional units in another example of MTN node.
  • aspects of the present invention provide methods according to which a communication network node and MTN network controller may communicate regarding transport resources to be allocated to user data being transported over an interface provided by the MTN.
  • An MTN controller defines a transport flow within the MTN, comprising at least one specified transport resource, and then communicates an identifier of the transport flow, together with at least one characteristic of the transport flow, to a communication network node.
  • the communication network node may then select an appropriate transport flow for a given user data packet, on the basis of the characteristic or characteristics communicated by the MTN controller, and may request allocation of the user data packet to the selected transport flow by referencing the identifier of the selected transport flow in a header of the user data packet.
  • the identifier assigned to the transport flow by the MTN controller may be a UDP port number, and may particularly be a UDP source port number, which the communication network node may write into the appropriate header field of the user data packet.
  • An MTN node receiving the user data packet may read the UDP source port number from the packet header and allocate the user data packet to the transport flow identified by the source port number.
  • Figure 3 illustrates a first example method 100 which may be conducted in a network controller of an MTN, the MTN providing a GTP based interface between nodes of a communication network.
  • the interface may be implemented using the GTPv1 -U protocol, specified in TS 29.281 , and may for example be an S1 -U interface in an LTE network between RAN and core network nodes.
  • the MTN network may be an optical, radio, microwave or other network type.
  • the network controller may for example be a Software Defined Network (SDN) controller or may be implemented as a distributed control plane or in any other manner.
  • the communication network nodes which communicate over the interface may for example be a RAN node and a core network node.
  • the communication network may for example be a GPRS, UMTS, LTE network etc.
  • the MTN network controller defines a transport flow within the MTN, the transport flow comprising at least one specified transport resource in the MTN.
  • the transport resource may take a range of different forms, according to the nature of the MTN network. Examples of transport resources which may be comprised within a defined transport flow include:
  • MPLS Multi Protocol Label Switching
  • LSP Label Switched Path
  • a Segment Routing LSP An IP tunnel, for example Generic Routing Encapsulation (GRE) or IPsec
  • GRE Generic Routing Encapsulation
  • IPsec IPsec
  • SDH Synchronous Digital Hierarchy
  • ATM Asynchronous Transfer Mode
  • a ring forwarding direction (clockwise, anti-clockwise)
  • the definition of the transport flow may also include at least one service provided to traffic allocated to the transport flow, as discussed in further detail with reference to Figure 4.
  • the MTN network controller associates an identifier with the defined transport flow, enabling the transport flow to be referenced via the identifier.
  • the identifier may be a UDP port number, and may for example be a UDP source port number.
  • TS 19.281 specifies a destination UDP port of 2152 but does not specify any particular value for the source port number. Using a UDP source port number as a transport flow identifier thus leaves the leaves the destination UDP port number to be set as 2152 and therefore maintains compatibility with TS 29.281 .
  • the MTN network controller communicates the identifier and at least one characteristic of the transport flow to a node of the communication network, which node may for example be one of the nodes on either side of the interface provided by the MTN.
  • a characteristic of the transport flow comprises a quality of the transport flow which may vary according to network conditions, including for example delay, delay variation, packet loss probability, available bandwidth, congestion status etc. Provision of one or more such characteristics, together with an identifier for the transport flow, may enable the communication node to select a particular transport flow for a user data packet, according to the transport flow characteristic(s), and to request allocation to that transport flow by writing the selected transport flow identifier into a header of the user data packet before forwarding the user data packet to the interface. This process is discussed in further detail with reference to Figure 5.
  • Communication of the transport flow identifier and characteristic or characteristics to the communication network node may be performed by the MTN network controller over an interface between the MTN and the communication network node.
  • an interface is described in patent application PCT/EP2015/063358, and may be implemented using the GTPv2-C protocol, specified in 3GPP TS 29.274.
  • This interface may in some examples be used by the MTN network controller to communicate the transport flow identifier and characteristic(s), for example by sending this information in a GTPv2-C protocol message, as illustrated in step 130a.
  • Figure 4 is a flow chart illustrating process steps in another example of a method 200 performed in an MTN network controller.
  • the method 200 of Figure 4 illustrates one way in which the steps of the method 100 of Figure 3 may be implemented and supplemented to provide the above discussed and additional functionality.
  • the MTN network controller defines a transport flow within the MTN, the transport flow comprising at least one specified transport resource in the MTN.
  • the defined transport flow also comprises at least one service provided to traffic allocated to the transport flow.
  • the service provided to traffic allocated to the transport flow may for example be a best effort service, a guaranteed performance service, reserved bandwidth etc.
  • Including one or more services in the definition of a transport flow may enable an MTN network controller to differentiate between different transport flows provided on the same resource. For example, two transport flows may be defined on a shortest path between source and destination nodes for an interface, the first transport flow having a guaranteed bandwidth and the second transport flow having a best effort service.
  • a third transport flow may be defined on another, longer path between the source and destination nodes, the longer path also having a best effort service.
  • all transport flows will have one or more characteristics associated with the resources forming the transport flow, including currently available bandwidth, delay, delay variation, packet loss probability, congestion status etc. One or more of these characteristics may be communicated to a communication network node as discussed below.
  • the MTN network then associates an identifier in the form of a UDP source port number to the defined transport flow.
  • the identifier enables the MTN network controller, communication network nodes and MTN nodes to reference particular transport flows in their communications.
  • a plurality of UDP source port numbers in the GTP protocol stack may be used to identify a plurality of different transport flows.
  • the MTN network controller communicates the identifier, at least one characteristic of the transport flow, and any service included in the definition of the transport flow to a node of the communication network. As discussed above, this communication may take place over an appropriate interface via the sending of a message, which may for example be a GTPv2-C message.
  • the method 200 may therefore include a step 240, in which the MTN controller detects a change in the, or at least one of the, characteristic(s) communicated to the communication network node. The MTN network then informs the communication network node of the changed characteristic(s) in step 242.
  • a communication network node may receive dynamic updates regarding the characteristics of one or more transport flows, enabling the communication network node to select a transport flow for particular user data packets on the basis of information that is up to date and reflects current conditions in the MTN.
  • characteristics which are qualities of the transport flow which may vary with network conditions
  • services provided to traffic allocated to a transport flow are defined by the MTN controller, and may be included in the definition of a transport flow, as discussed above.
  • the method 200 may include the step 250 of updating a service provided to traffic allocated to a transport flow, and the step 252 of communicating the updated service to the communication network node.
  • a communication network node may request an adjustment to a characteristic or service of a transport flow
  • the method 200 may include the step 160 of receiving a request from a communication network node to make such an adjustment.
  • a communication network node may make a request for an adjustment to reflect new traffic requirements, for example requesting an increase or decrease to a guaranteed bandwidth on a transport flow.
  • the method 200 may include the step 262 of making the requested adjustment, and may also confirm to the communication network node that the requested adjustment has been made.
  • the methods 100, 200 performed in an MTN controller may enable a communication network node to request allocation of a user data packet to a particular transport flow.
  • Figure 5 illustrates process steps in a method 300 which may be performed in a communication network node.
  • the communication network node may be a core network node or a RAN node, and may for example be an eNodeB, Serving Gateway (SGW), Packet Data Network Gateway (PGW), Radio Network Controller (RNC), Serving GPRS Support Node (SGSN), Mobile Switching Centre (MSC), Gateway GPRS Support Node (GGSN) etc.
  • SGW Serving Gateway
  • PGW Packet Data Network Gateway
  • RNC Radio Network Controller
  • SGSN Serving GPRS Support Node
  • MSC Mobile Switching Centre
  • GGSN Gateway GPRS Support Node
  • the method 300 comprises a first step 310 of receiving an identifier and at least one characteristic of a transport flow from a network controller of an MTN which is providing a GTP based interface via which the communication network node is connected to another node of the communication network.
  • the transport flow which is identified by the received identifier comprises at least one specified transport resource in the MTN, and may also comprise a service received by traffic allocated to the transport flow, which service may also be communicated to the communication network node with the identifier and one or more characteristics.
  • the characteristic(s) of the transport flow may include delay, delay variation, packet loss probability, congestion status, available bandwidth etc.
  • the service, if included in the transport flow may comprise a best effort service, a guaranteed performance service, reserved bandwidth etc.
  • the identifier, characteristic(s) and service may be received for example over an interface connecting the communication network node with the MTN network controller, as discussed above.
  • the interface may be a GTP based interface, and the identifier, characteristic(s) and service may be received in a message, such as a GTPv2-C protocol message.
  • the communication network node selects a user data packet for transmission to the other node of the communication network via the interface provided by the MTN in step 320.
  • the communication network node selects a transport flow for the selected user data packet in step 330.
  • the selection of a transport flow may involve matching a characteristic of a transport flow to a QoS or other requirement for the selected user data packet, as shown in step 330a. If a service is included in the definition of the transport flow, then the communication network node may also take this service into account in selecting an appropriate transport flow for the selected user data packet. In further examples, the communication network node may seek to balance optimal user experience with efficient network resource utilisation in selecting a transport flow for the selected user data packet. The communication network node may have received identifiers and characteristics for multiple transport flows, and may thus select the most appropriate for each individual user data packet to be forwarded to the interface.
  • the communication network node then includes the identifier of the selected transport flow in a header of the user data packet in step 340.
  • the transport flow identifier may be a UDP port number, and may in particular be a UDP source port number, which the communication network node may write into the UDP source port field of the UDP header of the user data packet, as shown in step 340a.
  • the UDP destination port number may be set as specified in the appropriate standards documents, ensuring that the method 300 remains compatible with existing standards.
  • the communication network node then forwards the user data packet to the interface for transmission to the other network node.
  • Methods 100, 200 and 300 thus together provide communication network nodes and the MTN with a common reference to identify transport resources in the MTN and enable improved management of MTN resources that provide an interface between communication network nodes.
  • the communication network node may additionally receive updates to the characteristics of one or more transport flows, as conditions within the MTN evolve over time.
  • the communication network node may also be notified of changes to services provided to traffic allocated to different transport flows, and may take these updates and notified changes into consideration in future selections of transport flows for user data packets.
  • the communication network node may request a change to a characteristic or service of a particular transport flow, for example to reflect changing requirements for user traffic.
  • Figure 6 illustrates an example method 400 which may take place in an MTN node such as a router, and illustrates how an MTN node may contribute to the management of resources by respecting the requested allocation to a transport flow.
  • the MTN node receives a user data packet from a first communication network node for transmission over the interface provided by the MTN to a second network node.
  • the MTN node extracts, from a header of the user data packet, a transport flow identifier for the user data packet.
  • the identifier may be a UDP source port number, which the MTN node may extract from the UDP source port field of the UDP header of the user data packet as shown in step 420a.
  • the MTN node then processes the user data packet onto the transport flow corresponding to the extracted identifier in step 430.
  • the nodes of the MTN ensure that traffic allocated to a particular transport flow travels along the resources included in the transport flow definition, and receives any services which are also included in the definition of the transport flow, as made by the MTN network controller according to the methods 100, 200.
  • the methods 100 and 200 may be carried out by a network controller of an MTN network, which may for example be implemented as an SDN controller or as a distributed control plane.
  • the methods 300 and 400 may be carried out respectively by a communication network node, which may be a RAN or a core network node, and by an MTN node such as a router.
  • Figure 7 illustrates an example MTN network controller 500 which may implement the methods 100, 200 for example on receipt of suitable instructions from a computer program.
  • the network node 500 comprises a processor 501 and a memory 502.
  • the memory 502 contains instructions executable by the processor 501 such that the network node 500 is operative to conduct some or all of the steps of the methods 100 and/or 200.
  • FIGs 8 and 9 illustrate examples of a communication network node 600 and an MTN node 700, which may implement the methods 300, 400 respectively, for example on receipt of suitable instructions from a computer program.
  • each of the communication network node 600 and MTN node 700 comprises a processor 601 , 701 and a memory 602, 702.
  • the memory 602, 702 contains instructions executable by the processor 601 , 701 such that the communication network node 600 is operative to conduct the method 300 and the MTN node 700 is operative to conduct the method 400.
  • FIG 10 illustrates an alternative example of MTN network controller 800, which may implement the methods 100, 200, for example on receipt of suitable instructions from a computer program.
  • the network controller carries out network control functions for the MTN, and may be implemented as a distributed control plane or may be an SDN controller.
  • the MTN controlled by the network controller may provide a GTP based interface between nodes of a communication network.
  • the communication network may for example be an LTE network and the interface may be an S1 -U interface.
  • the units illustrated in Figure 10 may be realised in any appropriate combination of hardware and/or software.
  • the units may comprise one or more processors and one or more memories containing instructions executable by the one or more processors.
  • the units may be integrated to any degree.
  • the network controller comprises a transport flow unit 810 for defining a transport flow within the MTN, the transport flow comprising at least one specified transport resource in the MTN.
  • the network controller also comprises an identifier unit 820 for associating an identifier with the defined transport flow, and a transmission unit 830 for communicating the identifier and at least one characteristic of the transport flow to a node of the communication network.
  • the identifier may be a UDP port number, which may be a UDP source port number.
  • the transmission unit 830 may be for sending a message over an interface to the node of the communication network, which interface may be a GTP based interface.
  • the message may be a GTPv2-C protocol message.
  • network controller 800 may further comprise a detecting unit 840 for detecting a change in the at least one characteristic of the transport flow, and the transmission unit 830 may be for communicating the changed characteristic to the node in the communication network.
  • the transport flow may comprise at least one service provided to traffic allocated to the transport flow, and the transmission unit 830 may be for communicating the service provided to traffic allocated to the transport flow to the node of the communication network.
  • Some examples of network controller 800 may further comprise an updating unit 850 for updating the service provided to traffic allocated to the transport flow, and the transmission unit 830 may be for communicating the updated service to the node of the communication network.
  • network controller 800 may further comprise a receiving unit 860 for receiving a request from a node of the communication network to amend at least one characteristic of the transport flow or at least one service provided to traffic allocated to the transport flow, and the transport flow unit 810 may be for amending the transport flow to provide the requested characteristic or service.
  • Figure 1 1 illustrates an alternative example of communication network node 900, which may implement the method 300, for example on receipt of suitable instructions from a computer program.
  • the communication network node 900 may in some examples be a part of an LTE network, and may be connected to another node of the communication network via a GTP based interface provided by an MTN, which interface may be an S1 -U interface.
  • MTN Mobility Management Entity
  • the units illustrated in Figure 1 1 may be realised in any appropriate combination of hardware and/or software.
  • the units may comprise one or more processors and one or more memories containing instructions executable by the one or more processors.
  • the units may be integrated to any degree.
  • the communication network node 900 comprises a receiving unit 910 for receiving an identifier and at least one characteristic of a transport flow from a network controller of the MTN, the transport flow comprising at least one specified transport resource in the MTN.
  • the communication network node 900 also comprises a user data packet unit 920 for selecting a user data packet for transmission to the other node and a transport flow unit 930 for selecting a transport flow for the user data packet.
  • the communication network node also comprises a header unit 940 for including the identifier of the selected transport flow in a header of the user data packet, and a transmission unit 950 for forwarding the user data packet to the interface for transmission to the other node.
  • the receiving unit 910 may be for receiving the identifier and at least one characteristic of the transport flow from a network controller of the MTN by receiving a message over an interface from the network controller of the MTN, which interface may be a GTP based interface, and the message may be a GTPv2-C protocol message.
  • the identifier may be a UDP port number, such as a UDP source port number
  • the header unit 940 may be for writing the UDP port number of the selected transport flow into a UDP port field of a UDP header of the user data packet.
  • the transport flow unit 930 may be for selecting a transport flow having a characteristic compatible with a quality of service requirement for the user data packet.
  • FIG 12 illustrates an alternative example of MTN node 1000, which may implement the method 400, for example on receipt of suitable instructions from a computer program.
  • the MTN node 1000 may be part of an MTN that provides a GTP based interface between first and second nodes of a communication network.
  • the communication network may for example be an LTE network and the interface may be an S1 -U interface.
  • the units illustrated in Figure 12 may be realised in any appropriate combination of hardware and/or software.
  • the units may comprise one or more processors and one or more memories containing instructions executable by the one or more processors.
  • the units may be integrated to any degree.
  • the MTN node comprises a receiving unit 1010 for receiving a user data packet from a first network node for transmission over the interface to the second network nod.
  • the MTN node also comprises a transport flow unit 1020 for extracting, from a header of the user data packet, a transport flow identifier for the user data packet, the transport flow comprising at least one specified transport resource in the MTN, and a processing unit 1030 for processing the user data packet onto the identified transport flow.
  • the identifier may comprise a UDP port number and the transport flow unit 1020 may be for reading a UDP port number from the UDP port field of a UDP header of the user data packet.
  • the UDP port field may be a UDP source port field.
  • aspects of the present invention provide methods enabling communication between an MTN network controller and a communication network node, providing a shared reference to identify transport resources in the MTN, and enabling the communication network node to request such resources for particular user data packets.
  • the reference used to identify transport resources may be the currently unspecified UDP source port number in the GTP protocol stack.
  • the UDP source port number, or other identifier uniquely identifies transport flows maintained by the MTN and comprising specified transport resources and, in some examples, specified services provided to traffic allocated to the transport flows.
  • the communication network node is provided not only with an identifier of a transport flow but also with at least one characteristic of the transport flow, enabling the communication network node to select an appropriate transport flow for each user data packet to be transported over an interface provided by the MTN. Selection of transport flows for user data packets may seek to optimize user experience and perceived service performance in addition to network resource usage. Characteristics of transport flows may be monitored by the MTN network controller, with updated characteristics provided to the communication network node as conditions in the MTN evolve. Communication between the MTN network controller and the communication network node may take place over an interface, such as a GTP based interface, which may use the GTPv2-C protocol.
  • the communication network node is able to select transport flows to ensure predictable service for user flows and MTN resource optimization. Fairness may also be implemented, with fair scheduling when multiplexing user flows on a transport flow with well defined characteristics.
  • the use of defined and identified transport flows also enables the MTN to implement load balancing, for example on Ethernet LAG or ECMP, by defining at least one transport flow per alternative path and keeping track of the used resources.
  • Unequal cost multipath may also be implemented with at least one transport flow per alternative path.
  • the methods of the present invention may be implemented in hardware, or as software modules running on one or more processors. The methods may also be carried out according to the instructions of a computer program, and the present invention also provides a computer readable medium having stored thereon a program for carrying out any of the methods described herein.
  • a computer program embodying the invention may be stored on a computer readable medium, or it could, for example, be in the form of a signal such as a downloadable data signal provided from an Internet website, or it could be in any other form.

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Abstract

A method (100), performed in a network controller of a Mobile Transport Network (MTN) is disclosed, the MTN providing a GPRS Tunnelling Protocol (GTP) based interface between nodes of a communication network. The method comprises defining a transport flow within the MTN (110), the transport flow comprising at least one specified transport resource in the MTN, associating an identifier with the defined transport flow (120), and communicating the identifier and at least one characteristic of the transport flow to a node of the communication network (130). Also disclosed is a method (300), performed by a node in a communication network, the node being connected to another node of the communication network via a GTP based interface provided by an MTN. The method comprises receiving an identifier and at least one characteristic of a transport flow from a network controller of the MTN (310), the transport flow comprising at least one specified transport resource in the MTN. The method further comprises selecting a user data packet for transmission to the other node (320), selecting a transport flow for the user data packet (330), including the identifier of the selected transport flow in a header of the user data packet (340), and forwarding the user data packet to the interface for transmission to the other node (350). Also disclosed are an MTN network controller (500, 800), a communication network node (600, 900), an MTN node (700, 1000) and a computer program product configured to carry out methods in an MTN network controller, a communication network node and an MTN node.

Description

Methods And Apparatus For Network Communication Over An Interface
Technical Field The present invention relates to methods performed in a network controller of a Mobile Transport Network (MTN), a node of a communication network and a node of an MTN. The present invention also relates to a computer program product configured, when run on a computer, to carry out methods performed in an MTN network controller, communication network node and MTN node.
Background
In existing mobile communication networks, user data is collected via Radio Base Stations of a Radio Access Network (RAN), and then sent via terrestrial transport networks towards nodes of a Core Network. Network components implementing the transport from RAN to Core Network nodes are generally referred to as a Mobile Transport Network (MTN) or Mobile Backhaul Network (MBH). The MTN implements an IP packet transport service (IP TNL) for the RAN, and the main interfaces used to transport user traffic between the RAN and the Core Nodes are implemented with the GPRS Tunnelling Protocol GTPv1 -U protocol, defined in TS 29.281.
Examples of interfaces implementing the GTPv1 -U protocol are set out in TS 29.281 and some of these interfaces are illustrated in Figure 1 , which shows an example LTE Radio and Core Network, taken from 3GPP TS 23.401 . Example interfaces include, in 2G networks the Gn and Gp interfaces of the General Packet Radio Service (GPRS), in 3G networks the lu, Gn and Gp interfaces of the UMTS system, and in 4G and 5G networks the S1 -U, X2, S4, S5, S8 and S12 interfaces of the Evolved Packet System (EPS). The S1 -U interface is a typical example of interfaces implementing the GTPvl - U protocol. The S1 -U interface is illustrated in Figure 1 between the eNodeBs of the E- UTRAN and the Serving Gateway (SGW) core node. The S1 -U interface transports flows for 4G networks and will also in the future transport flows in 5G networks.
Figure 2 illustrates the protocol stack of the GTPv1 -U protocol used to implement the S1 -U interface between an eNodeB and the SGW. The GTPv1 -U protocol stack multiplexes several user tunnels onto the same S1 -U interface. The GTP protocol itself is in turn carried over UDP packets, with common practice being to use a single pair of UDP source and destination ports for a given GTP tunnel in a radio base station. The UDP is in turn carried by IP packets.
The MTN implementing interfaces between RAN and core network nodes is typically deployed to include a degree of redundancy in its resources, in order to manage periods of very high traffic load or temporary unavailability of some part of the MTN, for example owing to malfunction or maintenance. In addition, an MTN is usually equipped with the means to provide different levels of quality of service to traffic flowing through the MTN. The provision of redundant resources in the MTN may mean that traffic carried by the MTN may follow a variety of different paths to its destination, the paths having different characteristics such as delay, delay variation, packet loss probability etc. Traffic may also experience service variations over time, as one or more paths become subject to congestion or other factors affecting the transport service provided by the MTN. These variations may be in addition to the varying service levels explicitly provided by the MTN to different types of traffic, for example via classification, customer service and bandwidth reservation policies which may be applied to traffic. Consequently, traffic being transported over a single interface of a communication network, the S1 -U interface for example, may be subject to a wide variety of service conditions provided by the MTN implementing the interface.
Aside from Quality of Service (QoS) information which may be available to MTN nodes through packet inspection of user data packets, there is no mechanism in existing networks for communication network nodes and an MTN providing interfaces between such nodes to communicate regarding the service levels experienced by user traffic being transported by the MTN. Even if control plane communication between communication network nodes and an MTN is possible, communication nodes are ignorant of the many different transport paths over which traffic may traverse an interface, and which may provide different service characteristics or be experiencing different levels of service variation.
Summary
It is an aim of the present invention to provide a method and apparatus which obviate or reduce at least one or more of the disadvantages mentioned above. According to a first aspect of the present invention, there is provided a method, performed in a network controller of a Mobile Transport Network (MTN) the MTN providing a GPRS Tunnelling Protocol (GTP) based interface between nodes of a communication network. The method comprises defining a transport flow within the MTN, the transport flow comprising at least one specified transport resource in the MTN, associating an identifier with the defined transport flow, and communicating the identifier and at least one characteristic of the transport flow to a node of the communication network. According to examples of the invention, the network controller carries out network control functions for the Mobile Transport Network, and may be implemented as a distributed control plane or may a Software Defined Network (SDN) controller. Examples of transport resources which may be specified in a defined transport flow may include:
A Multi Protocol Label Switching (MPLS) Label Switched Path (LSP)
A packet flow defined by classification rules
A Segment Routing LSP
An IP tunnel, for example Generic Routing Encapsulation (GRE) or IPsec
An optical wavelength, Course or Dense Wavelength Division Multiplexing
(CWDM or DWDM)
A Synchronous Digital Hierarchy (SDH) or Asynchronous Transfer Mode (ATM) legacy circuit
A Traffic Engineering tunnel
A ring forwarding direction (clockwise, anti-clockwise)
A protection mechanism
A service-chain
Traffic forwarding on different Radio Link uplinks (directed load-balancing). According to examples of the invention, the communication network may comprise a Long Term Evolution, LTE, network, and the interface may comprise an S1 -U interface. The interface may for example be implemented with GTPv1 -U, specified in TS29.281 .
According to examples of the invention, the identifier may comprise a User Datagram Protocol (UDP) port number. The UDP port number may for example be a source port number. According to examples of the invention, communicating the identifier and at least one characteristic of the transport flow to a node of the communication network may comprise sending a message over an interface to the node of the communication network.
According to examples of the invention, the interface to the node of the communication network, over which the message is sent, may comprise a GTP based interface. According to examples of the invention, the message may be a GTPv2-C protocol message, GTPv2-C being specified in TS29.274.
According to examples of the invention, the characteristic of the transport flow may comprise at least one of: delay, delay variation, packet loss probability, available bandwidth, congestion status.
According to examples of the invention, the method may further comprise detecting a change in the at least one characteristic of the transport flow, and communicating the changed characteristic to the node in the communication network.
According to examples of the invention, the transport flow may further comprise at least one service provided to traffic allocated to the transport flow.
According to examples of the invention, the service provided to traffic allocated to the transport flow may comprise at least one of: a best effort service, a guaranteed performance service, and/or a reserved bandwidth service.
According to examples of the invention, the method may further comprise communicating the service provided to traffic allocated to the transport flow to the node of the communication network.
According to examples of the invention, the method may further comprise updating the service provided to traffic allocated to the transport flow, and communicating the updated service to the node of the communication network. According to examples of the invention, the method may further comprise receiving a request from a node of the communication network to amend at least one characteristic of the transport flow or at least one service provided to traffic allocated to the transport flow, and amending the transport flow to provide the requested characteristic or service.
According to examples of the invention, the interface provided by the MTN may be between a cellular Radio Access Network, RAN, node and a core network node. Examples of such interfaces may include, in 2G networks the Gn and Gp interfaces of the General Packet Radio Service (GPRS), in 3G networks the lu, Gn and Gp interfaces of the UMTS system, and in 4G and 5G networks the S1 -U, X2, S4, S5, S8 and S12 interfaces of the Evolved Packet System (EPS).
According to examples of the invention, the node in the communication network may comprise a core network node.
According to another example of the present invention, there is provided a method, performed by a node in a communication network, the node being connected to another node of the communication network via a GPRS Tunnelling Protocol (GTP) based interface provided by a Mobile Transport Network (MTN). The method comprises receiving an identifier and at least one characteristic of a transport flow from a network controller of the MTN, the transport flow comprising at least one specified transport resource in the MTN, selecting a user data packet for transmission to the other node, selecting a transport flow for the user data packet, including the identifier of the selected transport flow in a header of the user data packet, and forwarding the user data packet to the interface for transmission to the other node.
Examples of communication network nodes which may carry out the method include an eNodeB, Serving Gateway (SGW), Packet Data Network Gateway (PGW), Radio Network Controller (RNC), Serving GPRS Support Node (SGSN), Mobile Switching Centre (MSC), Gateway GPRS Support Node (GGSN) etc.
According to examples of the invention, the communication network may comprise a Long Term Evolution (LTE) network and the interface may comprise an S1 -U interface. According to examples of the invention, receiving the identifier and at least one characteristic of the transport flow from a network controller of the MTN may comprise receiving a message over an interface from the network controller of the MTN. According to examples of the invention, the interface from the network controller of the MTN, over which the message is received, may comprise a GTP based interface.
According to examples of the invention, the message may be a GTPv2-C protocol message.
According to examples of the invention, the identifier may comprises a User Datagram Protocol (UDP) port number and including the identifier of the selected transport flow in a header of the user data packet may comprise writing the UDP port number of the selected transport flow into a UDP port field of a UDP header of the user data packet. The UDP port field may for example be a UDP source port field.
According to examples of the invention, selecting a transport flow for the user data packet may comprise selecting a transport flow having a characteristic compatible with a quality of service requirement for the user data packet.
According to another aspect of the present invention, there is provided a method, performed by a node in a Mobile Transport Network (MTN), the MTN providing a GPRS Tunnelling Protocol (GTP) based interface between first and second nodes of a communication network. The method comprises receiving a user data packet from a first network node for transmission over the interface to the second network node, extracting, from a header of the user data packet, a transport flow identifier for the user data packet, the transport flow comprising at least one specified transport resource in the MTN, and processing the user data packet onto the identified transport flow. According to examples of the invention, the communication network may comprise a Long Term Evolution (LTE) network and the interface may comprise an S1 -U interface.
According to examples of the invention, the identifier may comprises a User Datagram Protocol (UDP) port number and extracting the identifier of the transport flow from a header of the user data packet may comprises reading a UDP port number from the UDP port field of a UDP header of the user data packet. The UDP port field may for example be a UDP source port field.
According to another aspect of the present invention, there is provided a computer program configured when run on a computer, to carry out a method according to any one of the preceding aspects of the present invention.
According to another aspect of the present invention, there is provided a computer program product comprising computer readable material having stored thereon a computer program according to the preceding aspect of the present invention.
According to another aspect of the present invention, there is provided a network controller of a Mobile Transport Network (MTN), the MTN providing a GPRS Tunnelling Protocol (GTP) based interface between nodes of a communication network. The network controller comprises a transport flow unit for defining a transport flow within the MTN, the transport flow comprising at least one specified transport resource in the MTN, an identifier unit for associating an identifier with the defined transport flow, and a transmission unit for communicating the identifier and at least one characteristic of the transport flow to a node of the communication network.
According to examples of the invention, the network controller carries out network control functions for the Mobile Transport Network, and may be implemented as a distributed control plane or may a Software Defined Network (SDN) controller. According to examples of the invention, the communication network may comprise a Long Term Evolution (LTE) network and the interface may comprise an S1 -U interface.
According to examples of the invention, the identifier may comprise a User Datagram Protocol (UDP) port number, which may be a UDP source port number. According to examples of the invention, the transmission unit may be for sending a message over an interface to the node of the communication network.
According to examples of the invention, the interface to the node of the communication network, over which the message is sent, may comprise a GTP based interface. According to examples of the invention, the message may be a GTPv2-C protocol message.
According to examples of the invention, the network controller may further comprise a detecting unit for detecting a change in the at least one characteristic of the transport flow, and the transmission unit may be for communicating the changed characteristic to the node in the communication network.
According to examples of the invention, the transport flow may further comprise at least one service provided to traffic allocated to the transport flow.
According to examples of the invention, the transmission unit may be for communicating the service provided to traffic allocated to the transport flow to the node of the communication network.
According to examples of the invention, the network controller may further comprise an updating unit for updating the service provided to traffic allocated to the transport flow, and the transmission unit may be for communicating the updated service to the node of the communication network.
According to examples of the invention, the network controller may further comprise a receiving unit for receiving a request from a node of the communication network to amend at least one characteristic of the transport flow or at least one service provided to traffic allocated to the transport flow, and the transport flow unit may be for amending the transport flow to provide the requested characteristic or service.
According to another aspect of the present invention, there is provided a communication network node, the node being connected to another node of the communication network via a GPRS Tunnelling Protocol (GTP) based interface provided by a Mobile Transport Network (MTN). The node comprises a receiving unit for receiving an identifier and at least one characteristic of a transport flow from a network controller of the MTN, the transport flow comprising at least one specified transport resource in the MTN, and a user data packet unit for selecting a user data packet for transmission to the other node. The node further comprises a transport flow unit for selecting a transport flow for the user data packet, a header unit for including the identifier of the selected transport flow in a header of the user data packet, and a transmission unit for forwarding the user data packet to the interface for transmission to the other node.
According to examples of the invention, the communication network may comprise a Long Term Evolution (LTE) network and the interface may comprise an S1 -U interface.
According to examples of the invention, the receiving unit may be for receiving the identifier and at least one characteristic of the transport flow from a network controller of the MTN by receiving a message over an interface from the network controller of the MTN.
According to examples of the invention, the interface from the network controller of the MTN, over which the message is received by the receiving unit, may comprise a GTP based interface.
According to examples of the invention, the message may be a GTPv2-C protocol message.
According to examples of the invention, the identifier may comprise a User Datagram Protocol (UDP) port number and the header unit may be for writing the UDP port number of the selected transport flow into a UDP port field of a UDP header of the user data packet. The UDP port number may for example be a UDP source port number.
According to examples of the invention, the transport flow unit may be for selecting a transport flow having a characteristic compatible with a quality of service requirement for the user data packet.
According to another aspect of the present invention, there is provided a Mobile Transport Network (MTN) node, the MTN providing a GPRS Tunnelling Protocol (GTP) based interface between first and second nodes of a communication network. The MTN node comprises a receiving unit for receiving a user data packet from a first network node for transmission over the interface to the second network node, a transport flow unit for extracting, from a header of the user data packet, a transport flow identifier for the user data packet, the transport flow comprising at least one specified transport resource in the MTN, and a processing unit for processing the user data packet onto the identified transport flow. According to examples of the invention, the communication network may comprise a Long Term Evolution (LTE) network and the interface may comprise an S1 -U interface. According to examples of the invention, the identifier may comprises a User Datagram Protocol (UDP) port number and the transport flow unit may be for reading a UDP port number from the UDP port field of a UDP header of the user data packet. The UDP port field may be a UDP source port field. According to another aspect of the present invention, there is provided a network controller of a Mobile Transport Network (MTN), the MTN providing a GPRS Tunnelling Protocol (GTP) based interface between nodes of a communication network. The network controller comprises a processor and a memory, the memory containing instructions executable by the processor such that the network controller is operable to define a transport flow within the MTN, the transport flow comprising at least one specified transport resource in the MTN, associate an identifier with the defined transport flow, and communicate the identifier and at least one characteristic of the transport flow to a node of the communication network. According to examples of the invention, the network controller may carry out network control functions for the Mobile Transport Network. According to some examples, the network controller may be implemented as a distributed control plane. According to still further examples, the network controller may comprise a Software Defined Network (SDN) controller.
According to examples of the invention, the communication network may comprise a Long Term Evolution (LTE) network and the interface may comprise an S1 -U interface.
According to examples of the invention, the identifier may comprises a User Datagram Protocol (UDP) port number, and may comprise a UDP source port number.
According to examples of the invention, the network controller may be further operable to send a message over a GTP based interface to the node of the communication network. According to examples of the invention, the network controller may be further operable to detect a change in the at least one characteristic of the transport flow, and communicate the changed characteristic to the node in the communication network. According to examples of the invention, the transport flow may further comprise at least one service provided to traffic allocated to the transport flow, and the network controller may be further operable to communicate the service provided to traffic allocated to the transport flow to the node of the communication network. According to examples of the invention, the network controller may be further operable to update the service provided to traffic allocated to the transport flow, and communicate the updated service to the node of the communication network.
According to examples of the invention, the network controller may be further operable to receive a request from a node of the communication network to amend at least one characteristic of the transport flow or at least one service provided to traffic allocated to the transport flow, and amend the transport flow to provide the requested characteristic or service. According to another aspect of the present invention, there is provided a communication network node, the node being connected to another node of the communication network via a GPRS Tunnelling Protocol (GTP) based interface provided by a Mobile Transport Network (MTN). The node comprises a processor and a memory, the memory containing instructions executable by the processor such that the node is operable to receive an identifier and at least one characteristic of a transport flow from a network controller of the MTN, the transport flow comprising at least one specified transport resource in the MTN, and select a user data packet for transmission to the other node. The node is also operable to select a transport flow for the user data packet, include the identifier of the selected transport flow in a header of the user data packet, and forward the user data packet to the interface for transmission to the other node.
According to examples of the invention, the communication network may comprise a Long Term Evolution, LTE, network and the interface may comprise an S1 -U interface. According to examples of the invention, the identifier may comprises a User Datagram Protocol (UDP) port number and the node may be further operable to write the UDP port number of the selected transport flow into a UDP port field of a UDP header of the user data packet, which may be a source port field of the UDP header.
According to examples of the invention, the node may be further operable to select a transport flow having a characteristic compatible with a quality of service requirement for the user data packet. According to another aspect of the present invention, there is provided a Mobile Transport Network (MTN) node, the MTN providing a GPRS Tunnelling Protocol (GTP) based interface between first and second nodes of a communication network. The MTN node comprises a processor and a memory, the memory containing instructions executable by the processor such that the MTN node is operable to receive a user data packet from a first network node for transmission over the interface to the second network node, extract, from a header of the user data packet, a transport flow identifier for the user data packet, the transport flow comprising at least one specified transport resource in the MTN, and process the user data packet onto the identified transport flow.
According to examples of the invention, the communication network may comprise a Long Term Evolution, LTE, network and the interface may comprise an S1 -U interface.
According to examples of the invention, the identifier may comprises a User Datagram Protocol (UDP) port number and the MTN node may be further operable to read a UDP port number of from the UDP port field of a UDP header of the user data packet. The UDP port field may be a UDP source port field.
Brief description of the drawings
For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the following drawings in which: Figure 1 illustrates an example LTE Radio and Core Network; Figure 2 illustrates the protocol stack of the GTPv1 -U protocol used to implement an S1 -U interface;
Figure 3 is a flow chart illustrating process steps in a method performed in a network controller of an MTN;
Figure 4 is a flow chart illustrating process steps in another example of method performed in a network controller of an MTN; Figure 5 is a flow chart illustrating process steps in a method performed in a communication network node;
Figure 6 is a flow chart illustrating process steps in a method performed in an MTN node;
Figure 7 is a block diagram illustrating functional units in an MTN network controller;
Figure 8 is a block diagram illustrating functional units in a communication network node;
Figure 9 is a is a block diagram illustrating functional units in an MTN node;
Figure 10 is a block diagram illustrating functional units in another example of MTN network controller;
Figure 1 1 is a block diagram illustrating functional units in another example of communication network node; and
Figure 12 is a block diagram illustrating functional units in another example of MTN node.
Detailed description
Aspects of the present invention provide methods according to which a communication network node and MTN network controller may communicate regarding transport resources to be allocated to user data being transported over an interface provided by the MTN. An MTN controller defines a transport flow within the MTN, comprising at least one specified transport resource, and then communicates an identifier of the transport flow, together with at least one characteristic of the transport flow, to a communication network node. The communication network node may then select an appropriate transport flow for a given user data packet, on the basis of the characteristic or characteristics communicated by the MTN controller, and may request allocation of the user data packet to the selected transport flow by referencing the identifier of the selected transport flow in a header of the user data packet. In some examples of the invention, the identifier assigned to the transport flow by the MTN controller may be a UDP port number, and may particularly be a UDP source port number, which the communication network node may write into the appropriate header field of the user data packet. An MTN node receiving the user data packet may read the UDP source port number from the packet header and allocate the user data packet to the transport flow identified by the source port number.
Figure 3 illustrates a first example method 100 which may be conducted in a network controller of an MTN, the MTN providing a GTP based interface between nodes of a communication network. The interface may be implemented using the GTPv1 -U protocol, specified in TS 29.281 , and may for example be an S1 -U interface in an LTE network between RAN and core network nodes. The MTN network may be an optical, radio, microwave or other network type. The network controller may for example be a Software Defined Network (SDN) controller or may be implemented as a distributed control plane or in any other manner. The communication network nodes which communicate over the interface may for example be a RAN node and a core network node. The communication network may for example be a GPRS, UMTS, LTE network etc.
Referring to Figure 3, in a first step 1 10, the MTN network controller defines a transport flow within the MTN, the transport flow comprising at least one specified transport resource in the MTN. The transport resource may take a range of different forms, according to the nature of the MTN network. Examples of transport resources which may be comprised within a defined transport flow include:
A Multi Protocol Label Switching (MPLS) Label Switched Path (LSP)
A packet flow defined by classification rules
A Segment Routing LSP An IP tunnel, for example Generic Routing Encapsulation (GRE) or IPsec
An optical wavelength, Course or Dense Wavelength Division Multiplexing (CWDM or DWDM)
A Synchronous Digital Hierarchy (SDH) or Asynchronous Transfer Mode (ATM) legacy circuit
A Traffic Engineering tunnel
A ring forwarding direction (clockwise, anti-clockwise)
A protection mechanism
A service-chain
Traffic forwarding on different Radio Link uplinks (directed load-balancing).
It will be appreciated that these are merely examples of the kind of transport resources which may be comprised within a transport flow, and additional examples may be may be envisaged. In some examples, the definition of the transport flow may also include at least one service provided to traffic allocated to the transport flow, as discussed in further detail with reference to Figure 4.
In step 120, the MTN network controller associates an identifier with the defined transport flow, enabling the transport flow to be referenced via the identifier. In some examples, as illustrated in step 120a, the identifier may be a UDP port number, and may for example be a UDP source port number. It will be appreciated that TS 19.281 specifies a destination UDP port of 2152 but does not specify any particular value for the source port number. Using a UDP source port number as a transport flow identifier thus leaves the leaves the destination UDP port number to be set as 2152 and therefore maintains compatibility with TS 29.281 .
In step 130, the MTN network controller communicates the identifier and at least one characteristic of the transport flow to a node of the communication network, which node may for example be one of the nodes on either side of the interface provided by the MTN. A characteristic of the transport flow comprises a quality of the transport flow which may vary according to network conditions, including for example delay, delay variation, packet loss probability, available bandwidth, congestion status etc. Provision of one or more such characteristics, together with an identifier for the transport flow, may enable the communication node to select a particular transport flow for a user data packet, according to the transport flow characteristic(s), and to request allocation to that transport flow by writing the selected transport flow identifier into a header of the user data packet before forwarding the user data packet to the interface. This process is discussed in further detail with reference to Figure 5.
Communication of the transport flow identifier and characteristic or characteristics to the communication network node may be performed by the MTN network controller over an interface between the MTN and the communication network node. One example of such an interface is described in patent application PCT/EP2015/063358, and may be implemented using the GTPv2-C protocol, specified in 3GPP TS 29.274. This interface may in some examples be used by the MTN network controller to communicate the transport flow identifier and characteristic(s), for example by sending this information in a GTPv2-C protocol message, as illustrated in step 130a.
Figure 4 is a flow chart illustrating process steps in another example of a method 200 performed in an MTN network controller. The method 200 of Figure 4 illustrates one way in which the steps of the method 100 of Figure 3 may be implemented and supplemented to provide the above discussed and additional functionality.
Referring to Figure 4, in a first step 210, the MTN network controller defines a transport flow within the MTN, the transport flow comprising at least one specified transport resource in the MTN. In the illustrated example, the defined transport flow also comprises at least one service provided to traffic allocated to the transport flow. The service provided to traffic allocated to the transport flow may for example be a best effort service, a guaranteed performance service, reserved bandwidth etc. Including one or more services in the definition of a transport flow may enable an MTN network controller to differentiate between different transport flows provided on the same resource. For example, two transport flows may be defined on a shortest path between source and destination nodes for an interface, the first transport flow having a guaranteed bandwidth and the second transport flow having a best effort service. A third transport flow may be defined on another, longer path between the source and destination nodes, the longer path also having a best effort service.
Regardless of whether or not a service is included within a definition of a transport flow, all transport flows will have one or more characteristics associated with the resources forming the transport flow, including currently available bandwidth, delay, delay variation, packet loss probability, congestion status etc. One or more of these characteristics may be communicated to a communication network node as discussed below.
Having defined at least one transport flow in step 210, the MTN network then associates an identifier in the form of a UDP source port number to the defined transport flow. The identifier enables the MTN network controller, communication network nodes and MTN nodes to reference particular transport flows in their communications. A plurality of UDP source port numbers in the GTP protocol stack may be used to identify a plurality of different transport flows.
In step 230, the MTN network controller communicates the identifier, at least one characteristic of the transport flow, and any service included in the definition of the transport flow to a node of the communication network. As discussed above, this communication may take place over an appropriate interface via the sending of a message, which may for example be a GTPv2-C message.
As discussed above, all defined transport flows will have one or more characteristics associated with them, these characteristics giving an indication of the service that will be experienced by traffic allocated to the transport flow. In a majority of cases, these characteristics may vary with time, as conditions in different parts of the MTN evolve. The method 200 may therefore include a step 240, in which the MTN controller detects a change in the, or at least one of the, characteristic(s) communicated to the communication network node. The MTN network then informs the communication network node of the changed characteristic(s) in step 242. In this manner, a communication network node may receive dynamic updates regarding the characteristics of one or more transport flows, enabling the communication network node to select a transport flow for particular user data packets on the basis of information that is up to date and reflects current conditions in the MTN. In contrast to characteristics, which are qualities of the transport flow which may vary with network conditions, services provided to traffic allocated to a transport flow are defined by the MTN controller, and may be included in the definition of a transport flow, as discussed above. The method 200 may include the step 250 of updating a service provided to traffic allocated to a transport flow, and the step 252 of communicating the updated service to the communication network node. In some examples, a communication network node may request an adjustment to a characteristic or service of a transport flow, and the method 200 may include the step 160 of receiving a request from a communication network node to make such an adjustment. A communication network node may make a request for an adjustment to reflect new traffic requirements, for example requesting an increase or decrease to a guaranteed bandwidth on a transport flow. The method 200 may include the step 262 of making the requested adjustment, and may also confirm to the communication network node that the requested adjustment has been made. As discussed above, the methods 100, 200 performed in an MTN controller may enable a communication network node to request allocation of a user data packet to a particular transport flow. Figure 5 illustrates process steps in a method 300 which may be performed in a communication network node. The communication network node may be a core network node or a RAN node, and may for example be an eNodeB, Serving Gateway (SGW), Packet Data Network Gateway (PGW), Radio Network Controller (RNC), Serving GPRS Support Node (SGSN), Mobile Switching Centre (MSC), Gateway GPRS Support Node (GGSN) etc.
Referring to Figure 5, the method 300 comprises a first step 310 of receiving an identifier and at least one characteristic of a transport flow from a network controller of an MTN which is providing a GTP based interface via which the communication network node is connected to another node of the communication network. The transport flow which is identified by the received identifier comprises at least one specified transport resource in the MTN, and may also comprise a service received by traffic allocated to the transport flow, which service may also be communicated to the communication network node with the identifier and one or more characteristics. As discussed above, the characteristic(s) of the transport flow may include delay, delay variation, packet loss probability, congestion status, available bandwidth etc. The service, if included in the transport flow may comprise a best effort service, a guaranteed performance service, reserved bandwidth etc. The identifier, characteristic(s) and service may be received for example over an interface connecting the communication network node with the MTN network controller, as discussed above. The interface may be a GTP based interface, and the identifier, characteristic(s) and service may be received in a message, such as a GTPv2-C protocol message. Having received the identifier and characteristic(s), the communication network node then selects a user data packet for transmission to the other node of the communication network via the interface provided by the MTN in step 320. The communication network node then selects a transport flow for the selected user data packet in step 330. The selection of a transport flow may involve matching a characteristic of a transport flow to a QoS or other requirement for the selected user data packet, as shown in step 330a. If a service is included in the definition of the transport flow, then the communication network node may also take this service into account in selecting an appropriate transport flow for the selected user data packet. In further examples, the communication network node may seek to balance optimal user experience with efficient network resource utilisation in selecting a transport flow for the selected user data packet. The communication network node may have received identifiers and characteristics for multiple transport flows, and may thus select the most appropriate for each individual user data packet to be forwarded to the interface.
Once a transport flow has been selected for the user data packet, the communication network node then includes the identifier of the selected transport flow in a header of the user data packet in step 340. As discussed above, the transport flow identifier may be a UDP port number, and may in particular be a UDP source port number, which the communication network node may write into the UDP source port field of the UDP header of the user data packet, as shown in step 340a. The UDP destination port number may be set as specified in the appropriate standards documents, ensuring that the method 300 remains compatible with existing standards. The communication network node then forwards the user data packet to the interface for transmission to the other network node. The inclusion of the transport flow identifier in the UDP header of the user data packet acts as a request that the user data packet be allocated to the identified transport flow. Methods 100, 200 and 300 thus together provide communication network nodes and the MTN with a common reference to identify transport resources in the MTN and enable improved management of MTN resources that provide an interface between communication network nodes.
As discussed above with respect to Figure 4, the communication network node may additionally receive updates to the characteristics of one or more transport flows, as conditions within the MTN evolve over time. The communication network node may also be notified of changes to services provided to traffic allocated to different transport flows, and may take these updates and notified changes into consideration in future selections of transport flows for user data packets. In addition, the communication network node may request a change to a characteristic or service of a particular transport flow, for example to reflect changing requirements for user traffic. Figure 6 illustrates an example method 400 which may take place in an MTN node such as a router, and illustrates how an MTN node may contribute to the management of resources by respecting the requested allocation to a transport flow. Referring to Figure 6, in a first step 410, the MTN node receives a user data packet from a first communication network node for transmission over the interface provided by the MTN to a second network node. In step 420, the MTN node extracts, from a header of the user data packet, a transport flow identifier for the user data packet. As discussed above, the identifier may be a UDP source port number, which the MTN node may extract from the UDP source port field of the UDP header of the user data packet as shown in step 420a. The MTN node then processes the user data packet onto the transport flow corresponding to the extracted identifier in step 430. The nodes of the MTN ensure that traffic allocated to a particular transport flow travels along the resources included in the transport flow definition, and receives any services which are also included in the definition of the transport flow, as made by the MTN network controller according to the methods 100, 200.
As discussed above, the methods 100 and 200 may be carried out by a network controller of an MTN network, which may for example be implemented as an SDN controller or as a distributed control plane. The methods 300 and 400 may be carried out respectively by a communication network node, which may be a RAN or a core network node, and by an MTN node such as a router. Figure 7 illustrates an example MTN network controller 500 which may implement the methods 100, 200 for example on receipt of suitable instructions from a computer program. Referring to Figure 7, the network node 500 comprises a processor 501 and a memory 502. The memory 502 contains instructions executable by the processor 501 such that the network node 500 is operative to conduct some or all of the steps of the methods 100 and/or 200. Figures 8 and 9 illustrate examples of a communication network node 600 and an MTN node 700, which may implement the methods 300, 400 respectively, for example on receipt of suitable instructions from a computer program. Referring to Figures 8 and 9, each of the communication network node 600 and MTN node 700 comprises a processor 601 , 701 and a memory 602, 702. The memory 602, 702 contains instructions executable by the processor 601 , 701 such that the communication network node 600 is operative to conduct the method 300 and the MTN node 700 is operative to conduct the method 400.
Figure 10 illustrates an alternative example of MTN network controller 800, which may implement the methods 100, 200, for example on receipt of suitable instructions from a computer program. The network controller carries out network control functions for the MTN, and may be implemented as a distributed control plane or may be an SDN controller. The MTN controlled by the network controller may provide a GTP based interface between nodes of a communication network. The communication network may for example be an LTE network and the interface may be an S1 -U interface. It will be appreciated that the units illustrated in Figure 10 may be realised in any appropriate combination of hardware and/or software. For example, the units may comprise one or more processors and one or more memories containing instructions executable by the one or more processors. The units may be integrated to any degree.
Referring to Figure 10, the network controller comprises a transport flow unit 810 for defining a transport flow within the MTN, the transport flow comprising at least one specified transport resource in the MTN. The network controller also comprises an identifier unit 820 for associating an identifier with the defined transport flow, and a transmission unit 830 for communicating the identifier and at least one characteristic of the transport flow to a node of the communication network. As discussed above, the identifier may be a UDP port number, which may be a UDP source port number.
In some examples of the network controller 800, the transmission unit 830 may be for sending a message over an interface to the node of the communication network, which interface may be a GTP based interface. The message may be a GTPv2-C protocol message.
Some examples of network controller 800 may further comprise a detecting unit 840 for detecting a change in the at least one characteristic of the transport flow, and the transmission unit 830 may be for communicating the changed characteristic to the node in the communication network. In further examples, the transport flow may comprise at least one service provided to traffic allocated to the transport flow, and the transmission unit 830 may be for communicating the service provided to traffic allocated to the transport flow to the node of the communication network. Some examples of network controller 800 may further comprise an updating unit 850 for updating the service provided to traffic allocated to the transport flow, and the transmission unit 830 may be for communicating the updated service to the node of the communication network.
Some examples of network controller 800 may further comprise a receiving unit 860 for receiving a request from a node of the communication network to amend at least one characteristic of the transport flow or at least one service provided to traffic allocated to the transport flow, and the transport flow unit 810 may be for amending the transport flow to provide the requested characteristic or service.
Figure 1 1 illustrates an alternative example of communication network node 900, which may implement the method 300, for example on receipt of suitable instructions from a computer program. The communication network node 900 may in some examples be a part of an LTE network, and may be connected to another node of the communication network via a GTP based interface provided by an MTN, which interface may be an S1 -U interface. It will be appreciated that the units illustrated in Figure 1 1 may be realised in any appropriate combination of hardware and/or software. For example, the units may comprise one or more processors and one or more memories containing instructions executable by the one or more processors. The units may be integrated to any degree.
Referring to Figure 1 1 , the communication network node 900 comprises a receiving unit 910 for receiving an identifier and at least one characteristic of a transport flow from a network controller of the MTN, the transport flow comprising at least one specified transport resource in the MTN. The communication network node 900 also comprises a user data packet unit 920 for selecting a user data packet for transmission to the other node and a transport flow unit 930 for selecting a transport flow for the user data packet. The communication network node also comprises a header unit 940 for including the identifier of the selected transport flow in a header of the user data packet, and a transmission unit 950 for forwarding the user data packet to the interface for transmission to the other node.
The receiving unit 910 may be for receiving the identifier and at least one characteristic of the transport flow from a network controller of the MTN by receiving a message over an interface from the network controller of the MTN, which interface may be a GTP based interface, and the message may be a GTPv2-C protocol message.
As discussed above, the identifier may be a UDP port number, such as a UDP source port number, and the header unit 940 may be for writing the UDP port number of the selected transport flow into a UDP port field of a UDP header of the user data packet.
The transport flow unit 930 may be for selecting a transport flow having a characteristic compatible with a quality of service requirement for the user data packet.
Figure 12 illustrates an alternative example of MTN node 1000, which may implement the method 400, for example on receipt of suitable instructions from a computer program. The MTN node 1000 may be part of an MTN that provides a GTP based interface between first and second nodes of a communication network. The communication network may for example be an LTE network and the interface may be an S1 -U interface. It will be appreciated that the units illustrated in Figure 12 may be realised in any appropriate combination of hardware and/or software. For example, the units may comprise one or more processors and one or more memories containing instructions executable by the one or more processors. The units may be integrated to any degree.
Referring to Figure 12, the MTN node comprises a receiving unit 1010 for receiving a user data packet from a first network node for transmission over the interface to the second network nod. The MTN node also comprises a transport flow unit 1020 for extracting, from a header of the user data packet, a transport flow identifier for the user data packet, the transport flow comprising at least one specified transport resource in the MTN, and a processing unit 1030 for processing the user data packet onto the identified transport flow. As discussed above, the identifier may comprise a UDP port number and the transport flow unit 1020 may be for reading a UDP port number from the UDP port field of a UDP header of the user data packet. The UDP port field may be a UDP source port field.
Aspects of the present invention provide methods enabling communication between an MTN network controller and a communication network node, providing a shared reference to identify transport resources in the MTN, and enabling the communication network node to request such resources for particular user data packets. In some examples of the invention, the reference used to identify transport resources may be the currently unspecified UDP source port number in the GTP protocol stack. The UDP source port number, or other identifier, uniquely identifies transport flows maintained by the MTN and comprising specified transport resources and, in some examples, specified services provided to traffic allocated to the transport flows. The communication network node is provided not only with an identifier of a transport flow but also with at least one characteristic of the transport flow, enabling the communication network node to select an appropriate transport flow for each user data packet to be transported over an interface provided by the MTN. Selection of transport flows for user data packets may seek to optimize user experience and perceived service performance in addition to network resource usage. Characteristics of transport flows may be monitored by the MTN network controller, with updated characteristics provided to the communication network node as conditions in the MTN evolve. Communication between the MTN network controller and the communication network node may take place over an interface, such as a GTP based interface, which may use the GTPv2-C protocol.
Equipped with information about transport flow characteristics, and in some examples services provided on transport flows, the communication network node is able to select transport flows to ensure predictable service for user flows and MTN resource optimization. Fairness may also be implemented, with fair scheduling when multiplexing user flows on a transport flow with well defined characteristics. The use of defined and identified transport flows also enables the MTN to implement load balancing, for example on Ethernet LAG or ECMP, by defining at least one transport flow per alternative path and keeping track of the used resources. Unequal cost multipath may also be implemented with at least one transport flow per alternative path.
The methods of the present invention may be implemented in hardware, or as software modules running on one or more processors. The methods may also be carried out according to the instructions of a computer program, and the present invention also provides a computer readable medium having stored thereon a program for carrying out any of the methods described herein. A computer program embodying the invention may be stored on a computer readable medium, or it could, for example, be in the form of a signal such as a downloadable data signal provided from an Internet website, or it could be in any other form. It should be noted that the above-mentioned examples illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim, "a" or "an" does not exclude a plurality, and a single processor or other unit may fulfil the functions of several units recited in the claims. Any reference signs in the claims shall not be construed so as to limit their scope.

Claims

1 . A method, performed in a network controller of a Mobile Transport Network, MTN, the MTN providing a GPRS Tunnelling Protocol, GTP, based interface between nodes of a communication network, the method comprising:
defining a transport flow within the MTN, the transport flow comprising at least one specified transport resource in the MTN;
associating an identifier with the defined transport flow; and
communicating the identifier and at least one characteristic of the transport flow to a node of the communication network.
2. A method as claimed in claim 1 , wherein the communication network comprises a Long Term Evolution, LTE, network and wherein the interface comprises an S1 -U interface.
3. A method as claimed in claim 1 or 2, wherein the identifier comprises a User Datagram Protocol, UDP, port number.
4. A method as claimed in any one of claims 1 to 3, wherein communicating the identifier and at least one characteristic of the transport flow to a node of the
communication network comprises sending a message over an interface to the node of the communication network.
5. A method as claimed in claim 4, wherein the interface to the node of the communication network, over which the message is sent, comprises a GTP based interface.
6. A method as claimed in claim 4 or 5, wherein the message is a GTPv2-C protocol message.
7. A method as claimed in any one of the preceding claims, wherein the
characteristic of the transport flow comprises at least one of: delay, delay variation, packet loss probability, available bandwidth, congestion status.
8. A method as claimed in any one of the preceding claims, further comprising: detecting a change in the at least one characteristic of the transport flow; and communicating the changed characteristic to the node in the communication network.
9. A method as claimed in any one of the preceding claims, wherein the transport flow further comprises at least one service provided to traffic allocated to the transport flow.
10. A method as claimed in claim 9, wherein the service provided to traffic allocated to the transport flow comprises at least one of: a best effort service, a guaranteed performance service, a reserved bandwidth service.
1 1 . A method as claimed in claim 9 or 10, further comprising communicating the service provided to traffic allocated to the transport flow to the node of the
communication network.
12. A method as claimed in any one of claims 9 to 1 1 , further comprising:
updating the service provided to traffic allocated to the transport flow; and communicating the updated service to the node of the communication network.
13. A method as claimed in any one of the preceding claims, further comprising: receiving a request from a node of the communication network to amend at least one characteristic of the transport flow or at least one service provided to traffic allocated to the transport flow; and
amending the transport flow to provide the requested characteristic or service.
14. A method as claimed in any one of the preceding claims, wherein the interface provided by the MTN is between a cellular Radio Access Network, RAN, node and a core network node.
15. A method as claimed in any one of the preceding claims, wherein the node in the communication network comprises a core network node.
16. A method, performed by a node in a communication network, the node being connected to another node of the communication network via a GPRS Tunnelling Protocol, GTP, based interface provided by a Mobile Transport Network, MTN, the method comprising: receiving an identifier and at least one characteristic of a transport flow from a network controller of the MTN, the transport flow comprising at least one specified transport resource in the MTN;
selecting a user data packet for transmission to the other node;
selecting a transport flow for the user data packet;
including the identifier of the selected transport flow in a header of the user data packet; and
forwarding the user data packet to the interface for transmission to the other node.
17. A method as claimed in claim 16, wherein the communication network comprises a Long Term Evolution, LTE, network and wherein the interface comprises an S1 -U interface.
18. A method as claimed in any claim 16 or 17, wherein receiving the identifier and at least one characteristic of the transport flow from a network controller of the MTN comprises receiving a message over an interface from the network controller of the MTN.
19. A method as claimed in claim 18, wherein the interface from the network controller of the MTN, over which the message is received, comprises a GTP based interface.
20. A method as claimed in claim 18 or 19, wherein the message is a GTPv2-C protocol message.
21 . A method as claimed in any one of claims 16 to 20, wherein the identifier comprises a User Datagram Protocol, UDP, port number and wherein including the identifier of the selected transport flow in a header of the user data packet comprises writing the UDP port number of the selected transport flow into a UDP port field of a UDP header of the user data packet.
22. A method as claimed in any one of claims 16 to 21 , wherein selecting a transport flow for the user data packet comprises selecting a transport flow having a
characteristic compatible with a quality of service requirement for the user data packet.
23. A method, performed by a node in a Mobile Transport Network, MTN, the MTN providing a GPRS Tunnelling Protocol, GTP, based interface between first and second nodes of a communication network, the method comprising:
receiving a user data packet from a first network node for transmission over the interface to the second network node;
extracting, from a header of the user data packet, a transport flow identifier for the user data packet, the transport flow comprising at least one specified transport resource in the MTN; and
processing the user data packet onto the identified transport flow.
24. A method as claimed in claim 23, wherein the communication network comprises a Long Term Evolution, LTE, network and wherein the interface comprises an S1 -U interface.
25. A method as claimed in claim 23 or 24, wherein the identifier comprises a User Datagram Protocol, UDP, port number and wherein extracting the identifier of the transport flow from a header of the user data packet comprises reading a UDP port number from the UDP port field of a UDP header of the user data packet.
26. A computer program configured when run on a computer, to carry out a method according to any one of the preceding claims.
27. A computer program product comprising computer readable material having stored thereon a computer program as claimed in claim 26.
28. A network controller of a Mobile Transport Network, MTN, the MTN providing a GPRS Tunnelling Protocol, GTP, based interface between nodes of a communication network, the network controller comprising:
a transport flow unit for defining a transport flow within the MTN, the transport flow comprising at least one specified transport resource in the MTN;
an identifier unit for associating an identifier with the defined transport flow; and a transmission unit for communicating the identifier and at least one
characteristic of the transport flow to a node of the communication network.
29. A network controller as claimed in claim 28, wherein the identifier comprises a User Datagram Protocol, UDP, port number.
30. A network controller as claimed in claim 28 or 29, wherein the transmission unit is for sending a message over an interface to the node of the communication network.
31 . A network controller as claimed in claim 30, wherein the interface to the node of the communication network, over which the message is sent, comprises a GTP based interface.
32. A network controller as claimed in claim 30 or 31 , wherein the message is a GTPv2-C protocol message.
33. A network controller as claimed in any one of claims 28 to 32, further comprising: a detecting unit for detecting a change in the at least one characteristic of the transport flow; wherein
the transmission unit is for communicating the changed characteristic to the node in the communication network.
34. A network controller as claimed in any one of claims 28 to 33, wherein the transport flow further comprises at least one service provided to traffic allocated to the transport flow.
35. A network controller as claimed in claim 34, wherein the transmission unit is for communicating the service provided to traffic allocated to the transport flow to the node of the communication network.
36. A network controller as claimed in claim 34 or 35, further comprising:
an updating unit for updating the service provided to traffic allocated to the transport flow; wherein
the transmission unit is for communicating the updated service to the node of the communication network.
37 A network controller as claimed in any one of claims 28 to 36, further comprising: a receiving unit for receiving a request from a node of the communication network to amend at least one characteristic of the transport flow or at least one service provided to traffic allocated to the transport flow; wherein the transport flow unit is for amending the transport flow to provide the requested characteristic or service.
38. A communication network node, the node being connected to another node of the communication network via a GPRS Tunnelling Protocol, GTP, based interface provided by a Mobile Transport Network, MTN, the node comprising:
a receiving unit for receiving an identifier and at least one characteristic of a transport flow from a network controller of the MTN, the transport flow comprising at least one specified transport resource in the MTN;
a user data packet unit for selecting a user data packet for transmission to the other node;
a transport flow unit for selecting a transport flow for the user data packet;
a header unit for including the identifier of the selected transport flow in a header of the user data packet; and
a transmission unit for forwarding the user data packet to the interface for transmission to the other node.
39. A communication network node as claimed in claim 38, wherein the receiving unit is for receiving the identifier and at least one characteristic of the transport flow from a network controller of the MTN by receiving a message over an interface from the network controller of the MTN.
40. A communication network node as claimed in claim 39, wherein the interface from the network controller of the MTN, over which the message is received by the receiving unit, comprises a GTP based interface.
41 . A communication network node as claimed in claim 39 or 40, wherein the message is a GTPv2-C protocol message.
42. A communication network node as claimed in any one of claims 38 to 41 , wherein the identifier comprises a User Datagram Protocol, UDP, port number and wherein the header unit is for writing the UDP port number of the selected transport flow into a UDP port field of a UDP header of the user data packet.
43. A communication network node as claimed in any one of claims 38 to 42, wherein the transport flow unit is for selecting a transport flow having a characteristic compatible with a quality of service requirement for the user data packet.
44. A Mobile Transport Network, MTN, node, the MTN providing a GPRS Tunnelling Protocol, GTP, based interface between first and second nodes of a communication network, the MTN node comprising:
a receiving unit for receiving a user data packet from a first network node for transmission over the interface to the second network node;
a transport flow unit for extracting, from a header of the user data packet, a transport flow identifier for the user data packet, the transport flow comprising at least one specified transport resource in the MTN; and
a processing unit for processing the user data packet onto the identified transport flow.
45. An MTN node as claimed in claim 44, wherein the identifier comprises a User Datagram Protocol, UDP, port number and wherein the transport flow unit is for reading a UDP port number from the UDP port field of a UDP header of the user data packet.
46. A network controller of a Mobile Transport Network, MTN, the MTN providing a GPRS Tunnelling Protocol, GTP, based interface between nodes of a communication network, the network controller comprising a processor and a memory, the memory containing instructions executable by the processor such that the network controller is operable to:
define a transport flow within the MTN, the transport flow comprising at least one specified transport resource in the MTN;
associate an identifier with the defined transport flow; and
communicate the identifier and at least one characteristic of the transport flow to a node of the communication network.
47. A network controller as claimed in claim 46, wherein the identifier comprises a User Datagram Protocol, UDP, port number.
48. A network controller as claimed in claim 46 or 47, wherein the network controller is further operable to send a message over a GTP based interface to the node of the communication network.
49. A network controller as claimed in any one of claims 46 to 48, wherein the network controller is further operable to:
detect a change in the at least one characteristic of the transport flow; and communicate the changed characteristic to the node in the communication network.
50. A network controller as claimed in any one of claims 46 to 49, wherein the transport flow further comprises at least one service provided to traffic allocated to the transport flow.
51 . A network controller as claimed in claim 50, wherein the network controller is further operable to communicate the service provided to traffic allocated to the transport flow to the node of the communication network.
52. A network controller as claimed in claim 50 or 51 , wherein the network controller is further operable to:
update the service provided to traffic allocated to the transport flow; and communicate the updated service to the node of the communication network.
53. A network controller as claimed in any one of claims 46 to 52, wherein the network controller is further operable to:
receive a request from a node of the communication network to amend at least one characteristic of the transport flow or at least one service provided to traffic allocated to the transport flow; and
amend the transport flow to provide the requested characteristic or service.
54. A communication network node, the node being connected to another node of the communication network via a GPRS Tunnelling Protocol, GTP, based interface provided by a Mobile Transport Network, MTN, the node comprising a processor and a memory, the memory containing instructions executable by the processor such that the node is operable to:
receive an identifier and at least one characteristic of a transport flow from a network controller of the MTN, the transport flow comprising at least one specified transport resource in the MTN;
select a user data packet for transmission to the other node; select a transport flow for the user data packet;
include the identifier of the selected transport flow in a header of the user data packet; and
forward the user data packet to the interface for transmission to the other node.
55. A communication network node as claimed in claim 54, wherein the identifier comprises a User Datagram Protocol, UDP, port number and wherein the node is further operable to write the UDP port number of the selected transport flow into a UDP port field of a UDP header of the user data packet.
56. A communication network node as claimed in claim 54 or 55, wherein the node is further operable to select a transport flow having a characteristic compatible with a quality of service requirement for the user data packet.
57. A Mobile Transport Network, MTN, node, the MTN providing a GPRS Tunnelling Protocol, GTP, based interface between first and second nodes of a communication network, the MTN node comprising a processor and a memory, the memory containing instructions executable by the processor such that the MTN node is operable to:
receive a user data packet from a first network node for transmission over the interface to the second network node;
extract, from a header of the user data packet, a transport flow identifier for the user data packet, the transport flow comprising at least one specified transport resource in the MTN; and
process the user data packet onto the identified transport flow.
58. An MTN node as claimed in claim 57, wherein the identifier comprises a User Datagram Protocol, UDP, port number and wherein the MTN node is further operable to read a UDP port number of from the UDP port field of a UDP header of the user data packet.
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