[c-nsp] multicast bringing big irons to their knees?

[Paul Cosgrove]

Hi Christian,

You will need to explain more about the topology, your multicast setup
and the traffic flows, for instance:
- Are the foundary switches acting as your RPs?
- Have you any other commands applied which will cause multicasts to be
process switched?
- Do you have high rates of multicast on the network?
- Are you using any multicast groups which will appear the same as well
known multicast groups at Layer 2 (e.g. x.0.0.1, x.0.0.2 etc)?

If the Foundary switches are your RPs, the requirement to decapsulate
register messages could explain why these are affected much more than
your 6500s, 3750s and netscreens.  'ip pim register-rate-limit 5'
applied to the cisco designated routers will help if that is the problem
(not sure about equivalent netscreeen command).

Paul.

Christian MacNevin wrote:
> Hi
> I've only got the most superficial of ideas what's going on with this
> network, but i've been asked if there's any particular reason
> some Foundry switches would be being brought to their knees every time
> mcast is switched on in a network. 65s, 3750s and Netscreens
> all handle it fine.
> Given Foundry's marketing, they dobrag that everything's handled in
> port-based ASICs, but obviously it sounds like this stuff is going
> to the processor. Maybe it's PIM Sniffing not supported in hardware, not
> sure.
> Anyway, sorry for the amazing vagary here, but it's all I've got right
> now. Any thoughts?
> Cheers
> Christian_______________________________________________
> cisco-nsp mailing list  cisco-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-nsp
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> 


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