Anyone know if it is valid to have a Multicast group configured on a Cisco device yet have no traffic for that group? I am seeing some Catalyst 4006 devices with some groups in the IPM table but they have a value of 0 for the ipmRoutePkts. I was wondering how the groups got in there if there were no packets. These are for Group/Src entries with 0.0.0.0 as the src so this should be for any source on the group.
Thanks, Pat
Yes. Some groups are default.
These were for non-default groups.
The counters had values on some devices but not others. I was wondering if Cisco somehow added the groups to all the routers, or maybe if the 4006 devices had some problems updating it's counters. Even though some other 4006 devices had counter in them.
Which one?
Several - 228.1.0.28, 230.2.1.5, 230.3.0.3, and a lot more like these.
They are not default, they come from your client systems: show igmp groups.
I said they were non-default. I just wondered how they got on the router without any packet counter being incremented.
If a client subscribe the group, the router will show you those entries. If no sender feeds this group (or the TTL is to low to reach this router), the counters remain zero.
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