The MAG and the LMA exchange Heartbeat messages at regular intervals to detect the current status of reachability between the two of them. The MAG initiates the heartbeat exchange to test if the LMA is reachable by sending a Heartbeat Request message to the LMA. Each Heartbeat Request contains a sequence number that is incremented monotonically. Heartbeat Request messages are sent to LMA only if the MAG has at least one PMIPv6 session with a corresponding LMA. Similarly, the LMA also initiates a heartbeat exchange with the MAG by sending a Heartbeat Request message to check if the MAG is reachable.

Refer to the heartbeat CLI command in the LMA Service mode or MAG Service mode respectively to enable this heartbeat and configure the heartbeat variables.

The heartbeat messages are used only for checking reachability between the MAG and the LMA. They do not carry information that is useful for eavesdroppers on the path. Therefore, confidentiality protection is not required.

The sequence number sent in the Heartbeat Request message is matched when the Heartbeat response is received at the MAG/LMA. Before sending the next Heartbeat Request, the missing heartbeat counter is incremented if it has not received a Heartbeat Response for the previous request.

When the missing heartbeat counter exceeds the configurable parameter max-heartbeat-retransmission , the MAG/LMA concludes that the peer is not reachable. The heartbeat request to the peer will be stopped and a notification trap is triggered to indicate the failure.

If a heartbeat response message is received, then the missing heartbeat counter is reset.

The starPMIPPathFailure trap is cleared and the periodic heartbeat starts when the heartbeat request is received or when a new session is established from the corresponding peer.

Important

The failure detection at MAG will be the same as the one described in the Failure Detection figure for LMA.

MAG/LMA generates restart counter when the service is started. This counter is generated based on the service start timestamp. The restart counter is stored as part of the config and it is incremented whenever the service is restarted. The counter is not incremented if the sessions are recovered properly after a crash. MAG/LMA includes the restart counter mobility option in a heartbeat response message to indicate the current value of the restart counter. MAG/LMA also stores the restart counter values of all the peers with which it currently has PMIPv6 sessions.

After receiving the Heartbeat Response message, MAG/LMA compares the Restart Counter value with the previously received value. If the value is different, then it assumes that the peer had crashed and recovered. If the restart counter value changes or if there was no previously stored values, then the new value is stored for the corresponding peer.

The second heartbeat request in the Restart Detection figure is shown as a dashed arrow because the restart detection can happen even when an unsolicited heartbeat response is received with a change in restart counter.

The starPMIPPathFailure trap is cleared when the Heartbeat request is received or when a new session is established with the corresponding peer.

Important

The restart detection at MAG will the be same as the one described in Restart Detection figure for LMA.

The PMIPv6 Heartbeat functionality complies with the following standards:

The following command configures the PMIPv6 heartbeat message interval and retransmission timeout and max retransmission for the MAG/HSGW Service.

configure 
      context context_name 
            mag-service hsgw_svc_name 
                  heartbeat { interval seconds | retransmission { max number | timeout seconds } } 
                  default heartbeat { interval | retransmission { max | timeout } }  
                  no heartbeat  
                  end 

Notes:

The following command configures the PMIPv6 heartbeat message interval, retransmission timeout, and max retransmission for the LMA/P-GW Service.

configure 
      context context_name 
            lma-service pgw_lma_name 
                  heartbeat { interval seconds | retransmission { max number | timeout  seconds } } 
                  default heartbeat { interval | retransmission { max | timeout } } 
                  no heartbeat 
                  end 

Notes:

The following show commands can be used to verify the configured heartbeat configuration.

This section provides information regarding show commands and/or their outputs in support of the PMIPv6 Heartbeat.

The following Schema bulk statistics have been introduced for the PMIPv6 Heartbeat feature: