29 MBMS Heartbeat procedure

23.0073GPPRelease 18Restoration proceduresTS

The BM-SC, MBMS GW and GCS AS may support the MBMS Heartbeat procedure over the SGmb or MB2-C reference point to probe the liveliness and detect the restart of a peer MBMS node.

This procedure is optional to support and use for MBMS deployments without an intermediate Diameter Agent between the BM-SC and the MBMS GW or GCS AS. A BM-SC, MBMS GW or GCS AS which support the MBMS restoration procedures as specified in this specification shall support and use the MBMS Heartbeat procedure for MBMS deployments with an intermediate Diameter Agent between the BM-SC and MBMS GW or GCS AS.

The restart of a peer MBMS node is detected using a Restart-Counter AVP. The Restart-Counter AVP contains a value that is incremented monotonically whenever the MBMS node restarts with loss of previous states.

The MBMS Heartbeat Request and Answer messages shall contain the Restart-Counter AVP set to the local restart counter of the sending node. Other MBMS messages sent over the SGmb or MB2-C reference point may also contain the Restart-Counter AVP if contacting the peer node for the first time or if the local restart counter has been incremented.

Upon receipt of a Restart-Counter AVP in a MBMS Heartbeat Request or Answer or in any other SGmb or MB2-C signalling message, the receiving node shall compare the value of the received Restart-Counter AVP with the previous Restart counter value stored for this peer entity and

– if no previous value was stored, the Restart counter value received in the SGmb or MB2-C signalling message shall be stored for the peer;

– if the value of the received Restart-Counter AVP is greater than the Restart-Counter previously received from the same MBMS node, the receiver shall consider that the peer MBMS node has restarted.

An intermediate Diameter Agent shall not modify the Restart-Counter AVP when proxying SGmb or MB2-C signalling between the BM-SC and MBMS GW or GCS AS.

The BM-SC, MBMS GW and GCS AS shall support the detection of an SGmb or MB2-C path failure by sending an MBMS Heartbeat Request message periodically when no other signalling is exchanged over those interfaces between those nodes. The MBMS Heartbeat Request message shall be repeated one or more times if no MBMS Heartbeat Answer is received. The SGmb or MB2-C path shall be considered to be down if the peer MBMS node does not respond to a configured number of consecutive MBMS Heartbeart Requests. MBMS Heartbeat Requests shall only be sent on a per node basis (i.e. not on a per MBMS session basis).

See 3GPP TS 29.061 [31] and 3GPP TS 29.468 [35] for further details.