[c-nsp] IGMP explicit-tracking table overflow

[Phil Mayers]

On 30/01/14 08:51, Peter Rathlev wrote:
> We're recently started seeing messages like these on one of our
> L3-aggregation switches, a Sup720 running SXI3:
>
>   %MCAST-SP-6-ETRACK_STATS_LIMIT_EXCEEDED: Number of entries in
>      IGMP snooping explicit-tracking statistics has exceeded the
>      permanent threshold (25600)

Sigh. Yeah, we get that. It's annoying.

You can do:

clear ip igmp snooping statistics

...to get back on an even keel. However, for happy-fun-joy, these are 
replicated in a dual-sup setup, and you cannot clear them on the standby 
sup, so eventually you'll start getting -SPSTBY- versions of the message 
that never stop. Standby sup reload is the only solution :o(

> interface Vlan210
>   ip address 192.0.2.2 255.255.255.0
>   ip pim dr-priority 50
>   ip pim sparse-dense-mode
>   ip multicast boundary 70

You probably want "ip igmp access-group 70" here too, though it won't 
stop the stats getting gathered IIRC.

You can increase the global track limit to make it take longer between 
instances:

ip igmp snooping limit track 51200

I'm not sure if "0" disables it.


> We of course don't see the entries in the mroute table, but why does the
> switch collect statistics for something that's not allowed? I know it's
> just a warning, but it bothers me that the switch uses ressources (at
> least CPU) for something enough to give a warning and there's little I
> can do.

Yes it is really annoying.

> What do other people do? :-)

I opened a TAC and got a useless / fluff response. Now we ignore it and 
grit our teeth.