[c-nsp] IGMP Question - failed to create...

[Mihai Tanasescu]

Hi all,

I might be coming with a silly question now but my experience in 
Multicast is not so well developed.
On an equipment that I have access to, I just noticed some messages 
while activating IGMP debugging in a setup that was functional for some 
time and is still working now, albeit with some strange behavior.

Basically the topology looks like this:
Streaming Device --> Multicast Router (ASR) --> Distribution Switch 
(C4924-ME) --> IGMP proxies --> end hosts
The Distribution switch has:
- IGMP snooping enabled
- IGMPv3 support toward the Secondary network (although we don't use the 
extra functionality provided by IGMPv3...)
- is the IGMP querier.
All works well (or seems so) except for some corner cases when I noticed 
abnormal behavior.
Activating debug ip igmp snooping on the DS switch, I see things like below.

IGMPSN: group: Failed to create Host entry for 10.10.10.1, group 
239.10.23.22 on port Gi1/3
this in turn causes the other error upon 10.10.10.1 (an IGMP proxy in 
the secondary network) leaving the group:
IGMPSN: group: Leave from a non existant Host 10.10.10.1 group 
239.10.23.22 on port Gi1/3

10.10.10.1 = an IGMP proxy in the network connected to the DS (which is 
a black cloud for me)
VLC is running somewhere on a host behind the layer with the IGMP proxy, 
joining a mcast group and leaving it for my specific debugging.

I've been googling a bit without success and also activated more 
debugging but stil did not get a more meaningful idea about what is 
causing this.

Did anyone else stumble upon such behavior ?
Am I missing something that's really basic but escaping my eyes ?
I'd be very grateful for any kind of advice :) even to read the manual 
if I missed something that was way too obvious.

Thanks in advance,
Mihai