[c-nsp] Cat4500 High CPU with Multicast Stream

[Antonio Soares]

I will check that, in fact the 4500 is the first hop router.

 

 

Thanks.

 

Regards,

 

Antonio Soares, CCIE #18473 (R&S/SP)
 <mailto:amsoares at netcabo.pt> amsoares at netcabo.pt

 <http://www.ccie18473.net> http://www.ccie18473.net

 

 

From: Chris Evans [mailto:chrisccnpspam2 at gmail.com] 
Sent: quarta-feira, 13 de Julho de 2011 13:12
To: Antonio Soares
Cc: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] Cat4500 High CPU with Multicast Stream

 

Check the ttl on the multicast stream. A ttl of 1 will cause it to hit the
CPU of your first hop router.   

On Jul 13, 2011 8:02 AM, "Antonio Soares" <amsoares at netcabo.pt> wrote:
> Hello group,
> 
> I have a customer with a few 3560/3750's and one 4500/SUP5 acting as the
> core switch.
> 
> For some reason, when a user start one multicast stream, the 4500 suffers
> high cpu utilization and the network is affected. Only the 4500 suffers of
> this problem, the 3560/3750's don't have any complaints.
> 
> I see that the 4500 is a CEF based platform and I know that IP Multicast
is
> not supported in the CEF path. So I was expecting to have this traffic
> switched in hardware or fast-switched. But a packet capture shows me that
> the traffic goes to the cpu. I used this debug and output to confirm this:
> 
> debug platform packet all receive buffer
> 
> show platform cpu packet buffered
> 
> The processes that eat most of the cpu are "Cat4k Mgmt LoPri" and "Cat4k
> Mgmt HiPri". We thought this could be a bug and we upgraded the 4500 to
the
> latest release but the problem is exactly the same. The multicast stream
is
> processed by the cpu.
> 
> Anyone has seen this before ? Is this normal behavior of the 4500 ?
> 
> Usually the multicast streams are destined to 224.x.x.x. The end users do
> not respect the 239 rule.
> 
> 
> Thanks.
> 
> Regards,
> 
> Antonio Soares, CCIE #18473 (R&S/SP)
> amsoares at netcabo.pt
> http://www.ccie18473.net
> 
> 
> 
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