Tuesday, December 9, 2008

Multicast Heartbeat - Generating SNMP Traps

This was a topic I ran into while browsing the multicast configuration guide today. I had dynamips up and running so I created a small lab.



R1 is sending traffic to
R2 is the BSR/RP
R5 is will be configured for hearbeat
R7 has "ip igmp join-group" on one of its interfaces.

The commands to enable multicast heartbeat are very simple:

R5(config)#snmp-server host traps public ipmulticast
R5(config)#snmp-server enable traps ipmulticast

R5(config)#ip multicast heartbeat ?
<1-100> Minimal number of intervals where the heartbeats must be seen

R5(config)#ip multicast heartbeat 1 ?
<1-100> Number of intervals to monitor for heartbeat

R5(config)#ip multicast heartbeat 1 2 ?
<10-3600> Length of intervals in seconds

R5(config)#ip multicast heartbeat 1 2 10

You will see this message:

*Mar 1 00:29:58.523: MHBEAT(0): Unless packets sent to are seen in 1 out of 2 intervals of 10 seconds, an SNMP trap may be emitted.

Let's debug SNMP packets and the heartbeat so we can see the trap:

R5#debug snmp packets
SNMP packet debugging is on
R5#debug ip mhbeat
IP multicast heartbeat debugging is on

Now on R1 start sending packets, then stop:

R1#ping re 2

Type escape sequence to abort.
Sending 10, 100-byte ICMP Echos to, timeout is 2 seconds:

Reply to request 0 from, 160 ms
Reply to request 1 from, 148 ms

Let's check R5. After a short while we see the following:

*Mar 1 00:38:48.555: MHBEAT(0): SNMP Trap for missing heartbeat
*Mar 1 00:38:48.575: SNMP: Queuing packet to
*Mar 1 00:38:48.575: SNMP: V1 Trap, ent ciscoExperiment.2.3.1, addr, gentrap 6, spectrap 1
ciscoIpMRouteHeartBeatEntry. =
ciscoIpMRouteHeartBeatEntry. = 10
ciscoIpMRouteHeartBeatEntry. = 2
ciscoIpMRouteHeartBeatEntry. = 0
*Mar 1 00:38:48.827: SNMP: Packet sent via UDP to

For reference, here is the link to the DocCD:

IP Multicast Heartbeat

No comments:

Post a Comment

Note: Only a member of this blog may post a comment.