Path Failure Handling

Upon detecting a path failure, the network node notifies the failure through the Operation and Maintenance system and performs the following:

  • Deletes the PDN connections (EPS bearer contexts) or the associated PDP contexts with peer IP address.

  • Specifies the following actions for the selected interface:

    • Local Purge: The cnSGW-C clears the affected bearer (or PDN if the default bearer receives the path failure) locally without informing the peer. This action is default for all interfaces.

      Note

      cnSGW-C sends the Sx Session Delete Request to UPF to clear session on path failure detection.

    • Signal-Peer: The cnSGW-C sends control signal towards the peer MME and P-GW.

      When signaling:

      • For PDN deletion, the SGW sends a Delete Session Request message to the PGW and a Delete Bearer Request (with LBI) message to the MME.

      • SGW sends a Delete Request on the S11 or the S5 interface to notify the peer.

Note

Echo Request exchange is stopped when the peer is deleted.