Question: What is the primary purpose of the MBMS heartbeat procedure between the BM-SC and MBMS GW?
Option 1: To negotiate the use of SGmb messages
Option 2: To detect an SGmb path failure or the restart of the peer MBMS node
Option 3: To maintain a local restart counter for MBMS sessions
Option 4: To apply the procedure per MBMS session
Explanation: The MBMS heartbeat procedure is used to detect an SGmb path failure or the restart of the peer MBMS node, as specified in 3GPP TS 23.007 [Restoration procedures]. This allows the BM-SC and MBMS GW to take necessary actions to restore communication and maintain service continuity.