[j-nsp] Multicast/Broadcast Packets going to EX CPU

[Sebastian Wiesinger]

* Phil Mayers <p.mayers at imperial.ac.uk> [2014-03-05 19:12]:
> >Chris, can you elaborate on why low TTL on multicast frames will
> >cause high CPU?
> >
> >Sebastien, as Chris pointed out anything in the 224.0.0.0/24 will hit
> >the CPU, but so will a few other ranges that fall into the Link-Local
> 
> There's no inherent reason these packets need to hit the CPU on a
> purely layer2 vlan, any more than broadcast or unknown-unicast
> packets have to.

+1

> It might be that the architecture of the device - either by
> necessity, choice or neglect, and either hardware or software -
> means these packets hit the CPU, but just being link-local or
> multicast doesn't imply it.

Yes I see it the same way. And now I'm looking for countermeasures for
this. :) Most of the answers here are in the line of "Yes, this is
what happens" so it seems there is no secret knob to turn this off
(mind you, Cisco has something like this on their Cat4500 after they
realised this was a problem).

So what to do? Have storm-control everywhere? Is this all one can do?

Regards

Sebastian

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