Re: [nsp] Forwarding latency corellated to CPU utilization

From: Jared Mauch (jared@puck.nether.net)
Date: Fri Jul 12 2002 - 14:39:51 EDT


        Sounds like a bug. I'd open a tac case and get them to
track the issue down for you.

        Also, you might want to try 12.0(21)ST for your mpls voodoo
instead as it supports your hardware, unless there is something
that requires you to run 12.2T that isn't listed here.

        (or even 12.0(21)S3 as it has been very stable in my
experience).

        - jared

On Fri, Jul 12, 2002 at 02:30:25PM -0400, Przemyslaw Karwasiecki wrote:
> All,
>
> I have recently encountered interesting phenomenon:
>
> On cisco 7206 working in a typical configuration in ISP environment
> (BGP, ISIS, MPLS), I have noticed that traffic forwarded from
> ATM interface (PA-A3-OC3) to T1 interface (PA-8CT1) is prone
> to increased forwarding latency (up to 700ms!) while CPU utilization
> is high (during typical spikes while BGP scenner or ISIS SPF runs).
>
> This is happening only when forwarded packets are arriving as MPLS,
> and egressing as normal IP HDLC frames. In other words, router is
> removing MPLS label (penultimate hop).
>
> As soon as I disabled tag switching on ATM, problem is gone.
>
> IOS version is 12.2(8)T4.
>
> Is it a feature or bug?
>
> I can replicate it easily.
>
> Thanks,
>
> Przemek

-- 
Jared Mauch  | pgp key available via finger from jared@puck.nether.net
clue++;      | http://puck.nether.net/~jared/  My statements are only mine.



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