Multicast Source objects are getting pruned during post processing

Products

• VMware Smart Assurance
• Network Observability

Issue/Introduction

Symptoms:

• Discovered a Multicast (MCAST) enabled router into my IP topology. 
• It is properly picked up in IP and also in MCAST topology. 
• During the discovery, it shows that it's discovering Multicast Source. 
• However, it gets pruned in the MCAST post processing stage. 
• The end result of the MCAST topology is without the Multicast Source object.

Environment

All Supported Smarts releases

Cause

The reason the Multicast Source that wasn't discovered is because the source of the MCAST is not within the topology.

If a Multicast device or a set of Multicast devices were discovered into the topology and none of these Multicast devices are the source of the Multicast signal, it will prune the Multicast Source object that's created during the discovery in the post processing stage. 

These Multicast sources discovered and pruned are considered as stale Multicast sources.

Resolution

Comment out "PURGE_STALE_SOURCES" from the process in the mcast-post.asl file and run a rediscover in the source domain (IP domain).

The Multicast source will be discovered and will not be pruned during the post processing stage. 

However, this is still a stale MCAST source and much of the SNMP information will not be populated.  This means that monitoring will not occur since no instrumentation object is built for the stale MCAST source.