On 03/03/2014 19:38, Peter Rathlev wrote:
layer-2, is using the "desktop default" SDM template and has no IPv6 features (like MLD snooping) configured.
Are you absolutely sure about this? Isn't MLD snooping on by default?
They are multicast listener reports, and there are far far too many of them from each PC. That is a "problem" with the PC which other people are (supposed to be) looking at.
I wonder if it's the same thing we (and others) saw: http://lists.cluenet.de/pipermail/ipv6-ops/2014-February/009835.html
What I don't understand is why this ends up in a CPU queue on a 3560. Shouldn't the "Router Alert" option only be picked up by devices doing L3 forwarding? We see several switches with these symptoms but also several without. Even switches which are almost identical in configuration, hardware and IOS behave differently.
Big surprise there; Cisco being inconsistent!
So apart from just blocking all IPv6 (which wouldn't be hard, but feels like going the wrong way) what can I do? :-)
I can't remember if c3k can do multicast storm limiting without bad side effects; that is how we solved our problem. In particular if it is the same thing (AMT/vPro) we found that even a modest rate-limit closed the flood storms down completely, as they seem to be caused by "reflection".
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