[c-nsp] Log messages saying %MCAST-SP-3-QUERY_INT_MISMATCH

[Jeroen van Ingen]

On Fri, 2011-10-07 at 11:42 +0100, Phil Mayers wrote:
> A couple of our 6500/sup720 are logging:
> 
> %MCAST-SP-3-QUERY_INT_MISMATCH: Snooping Querier received a non-matching 
> query interval (125000 msec)
> 
> ...quite frequently. This is annoying, because it fills the logs and 
> (curse you cisco!) it doesn't say from whom it "received" a non-matching 
> blah, or even what interface.

We occasionally see a similar message, but it's a bit more informational
in the sense that it logs the source IP for the query:

%IGMP-3-QUERY_INT_MISMATCH: Received a non-matching query interval 125,
from querier address 10.10.10.139

This is on a Cat6k Sup720-3B running SXI2a, which is the IGMP Querier
for the segment in question.

> This is a really busy box, so a debug or packet capture isn't a great 
> way to find the cause. Any suggestions? And I'd be grateful if those of 
> you about to say "just ignore it" could assume I'm aware of that option 
> and move on ;o)

Actually, we generally do ignore these messages; if I remember
correctly, they're usually triggered by Linux/Unix boxes running an
IGMPv1 querier for some reason. We've never seen this having impact on
multicast forwarding; the L2 switches doing IGMP snooping don't log any
querier changes either and I've never had an IPTV complaint from a
timeframe where one of these messages was logged...

Are the boxes you're seeing this on acting as queriers, or are they just
doing IGMP snooping?


Regards,

Jeroen van Ingen
ICT Service Centre
University of Twente, P.O.Box 217, 7500 AE Enschede, The Netherlands