EP-3777039-B1 - IMPROVEMENTS ON DETECTION AND HANDLING OF FAILURE ON USER PLANE PATH

Inventors

• GAN, Juying
• CHEN, QIAN

Dates

Publication Date

20260506

Application Date

20190326

Claims (9)

1. A method (500) of handling user plane path failures in a telecommunication network including a core network and an access network, comprising: receiving (501), by a Session Management Function, SMF, in the core network, a notification regarding a failure on a user plane path between the access network and the core network from an endpoint of the user plane path, wherein the endpoint is a base station, BS, or a User Plane Function, UPF, the other endpoint of the user plane path is the UPF or the BS; characterized by handling (502), by the SMF, the failure, including marking the user plane path as being temporarily unavailable and reselecting a different UPF; and if the SMF considers reselecting a different UPF will not resolve the path failure problem, releasing, by the SMF, a PDU session related to the user plane path and reporting the failure to an Access and Mobility Management Function, AMF, in the core network.
2. The method of claim 1, wherein the notification is received when the user plane path is being established by the SMF or after the user plane path is established.
3. The method of claim 1 or 2, wherein, when the failure is reported to the AMF, the AMF takes the path failure into consideration for selecting an SMF during establishment of another PDU session related to the user plane path.
4. The method of any of claims 1 to 3, further comprising detecting (301), by the endpoint of the user plane path, whether a failure exists on the user plane path or not; and notifying (302) the SMF of the failure.
5. The method of claim 4, wherein the endpoint performs the detecting when the user plane path is being established by the SMF or after the user plane path is established.
6. A Session Management Function, SMF (1400) in a core network in a telecommunication network, the SMF being configured to perform the method according to any one of claims 1 or 2.
7. A telecommunication network including a core network and an access network, comprising - a session management function, SMF, according to claim 6 and - a base station, BS, and/or a user plane function, UPF, acting as an endpoint of a user plane path between the access network and the core network, the BS and/or the UPF being configured to detect (301) whether a failure exists on the user plane path or not and to notify (302) the SMF of the failure.
8. The telecommunication network of claim 7, wherein the BS and/or UPF is configured to perform the detecting when the user plane path is being established by the SMF or after the user plane path is established.
9. The telecommunication network of claim 7 or 8, further comprising an Access and Mobility Management Function, AMF, in the core network, the AMF being configured to receive a report of the failure from the SMF and taking the path failure into consideration for selecting an SMF during establishment of another PDU session related to the user plane path.

Description

TECHNICAL FIELD The present disclosure relates to the technical field of a telecommunication network including an access network and a core network, particularly to methods and nodes for improving detection and handling of failure on user plane path between the access network and the core network. BACKGROUND In the long term evolution of the telecommunication network including an access network and a core network, the interface (or the reference point) between the access network and the core network is divided into a user plane and a control plane. The user plane can carry the user data and the control plane can carry the control information. For example, in the Evolved Packet System (EPS), a user plane called as S1-U exists between the Evolved Universal Terrestrial Radio Access Network (E-UTRAN) and the Serving Gateway (SGW), as shown in figure 1. As another example, in the 5th generation (5G) system, a user plane called as N3 exists between the (R)AN and the User Plane Function (UPF), as shown in figure 2. A user plane path may need to be established in some procedures in the telecommunication network to allow communication of user data. For example, a bearer or a tunnel on the user plane needs to be established in the UE requested PDN connectivity procedure. Figure 3 illustrates the UE requested PDN connectivity procedure for the E-UTRAN in the EPS. The procedure allows the UE to request for connectivity to an additional PDN over E-UTRAN including allocation of a default bearer. This procedure could be a standalone or as part of initial Attach. To set up the bearer, in step 7 in figure 3, the Mobility Management Entity (MME) sends PDN Connectivity Accept Session Management Request (APN, PDN Type, PDN Address, EPS Bearer Id, Protocol Configuration Options, Header Compression Configuration, Control Plane Only Indicator) message to the UE. If the PDN connection uses the user plane over the radio, this message is contained in an S1_MME control message Bearer Setup Request (EPS Bearer QoS, UE-AMBR, PDN Connectivity Accept, S1-TEID) to the eNodeB. The message includes the TEID at the Serving GW used for user plane and the address of the Serving GW for user plane. And in step 10 in figure 3, the eNodeB sends an S1-AP Bearer Setup Response to the MME. The S1-AP message includes the TEID of the eNodeB and the address of the eNodeB used for downlink traffic on the S1-U reference point. 3GPP TS 23.007 prescribes user plane path failure detection and handling for a user plane path. The following are the contents regarding user plane path failure detection and handling in 3GPP TS 23.007: "20.3 User plane path failure detection and handling 20.3.1 General GTP-U entities shall support detection of path failure by using Echo Request/Echo Response messages in the following way. A path counter shall be reset each time an Echo Response is received on the path and incremented when the T3-RESPONSE timer expires for any Echo Request message sent on the path. The path shall be considered to be down if the counter exceeds N3-REQUESTS. Upon detecting a path failure, the network node should notify the failure via the Operation and Maintenance system and may eitherdelete the bearer contexts associated with the path in failure; ormaintain the bearer contexts associated with the path in failure during an operator configurable maximum path failure duration. The network node shall delete the maintained resources if the path is still down when this duration expires. 20.3.4 With Control and User plane Separation of SGW or PGW nodes With a split SGW or PGW (see 3GPP TS 23.214 [42]), user plane path failure detection and handling shall be supported as specified in subclause 20.3.1 with the following additional requirements:upon detecting a GTP-U user plane path failure, the SGW-U or PGW-U shall report the user plane path failure to the SGW-C or PGW-C respectively, by sending an Sx Node Report Request (see 3GPP TS 29.244 [43]) including a User Plane Path Failure Report with the IP address of the remote GTP-U peer(s) towards which a failure has been detected;upon being notified about the user plane path failure, when deciding to delete the bearer contexts associated with the path in failure, the SGW-C or PGW-C shall modify or delete the affected Sx sessions in the SGW-U or PGW-U". SUMMARY The scope of the invention is defined by the appended claims. Further embodiments of the invention are defined by the dependent claims. The inventors of the present disclosure find, in the current mechanisms for user plane path failure detection and handling, the following problems exist (taking the EPS for example): 1) At the user plane path establishment between base station (BS) and SGW, when the BS receives the allocated SGW tunnel info, or when the SGW receives the allocated BS tunnel info, the current standard doesn't specify if the aliveness of the S1-U path should be checked in the endpoint (i.e., the BS and/or SGW). Consequently, the EPS bearer ma