[c-nsp] troubleshooting SVI input drops on MSFC3

[Church, Charles]

Sending ICMP redirects for all those?

Chuck

--- Original Message ---
From:"barney gumbo" <barney.gumbo at gmail.com>
Sent:Wed 5/9/07  12:15 pm
To:"Dale W. Carder" <dwcarder at doit.wisc.edu>
Cc:"cisco-nsp at puck.nether.net" <cisco-nsp at puck.nether.net>
Subj:Re: [c-nsp] troubleshooting SVI input drops on MSFC3

I have a little more info this time..

It appears that the traffic is being process switched.

It started when this switch became more of a "router on a stick".
Previously most traffic flowed from one SVI to the other; this 6503 is
essentially an access or WAN router.  Now traffic flows from routers on the
same VLAN into the SVI and then back out of the SVI to get to the next hop,
which is a firewall, all on the same VLAN.

It seems like once the flow volume hits around 40 Mbps, the input drops
begin.

Going away from the router-on-a-stick design, where the bulk of the traffic
transit's across the switch instead of in/out the same interface, is not a
trivial change, so I would like to try and get some confidence that this is
related to the problem before I start to make changes.  This is all just a
guess, but it's the only major thing that has changed in the last week.

Any ideas if this could be my cause of process-switchng and input drops?

Any ideas on how I can verify the router-on-a-stick forwarding is definitely
to blame?

On 5/9/07, Dale W. Carder <dwcarder at doit.wisc.edu> wrote:
>
>
> Here's some commands to get you started:
>
> sh buffers input-interface
> sh int vlan1234 switching
> sh ip interface
> sh ip traffic
> sh cef drop
> sh ip cache flow
> sh cef not-cef-switched
>
> Some more help can be found here:
> http://www.cisco.com/warp/public/63/queue_drops.html
>
> You also might want to verify that you didn't configure a feature
> that causes punts.
>
> If you really want to get dirty, you can create a span session to
> monitor traffic destined to the RP.  This has been discussed on this
> list once or twice, but it is a bit messy.
>
> Dale
>
>
> On May 9, 2007, at 9:43 AM, barney gumbo wrote:
>
> > I am seeing high input interface drops on an SVI interface on an
> > MSFC3.  The
> > MSFC3 is installed in a 6503 chassis with Sup720.  The switch is
> > running
> > hybird mode.
> >
> > The traffic load has increased, and CPU is running high when the
> > traffic
> > load increases.  I don't know why the SVI is showing increased
> > traffic load
> > because normally I don't see traffic through the SVI, it all get's MLS
> > switched.  Something in the last week has caused traffic to be
> > switched
> > through the SVI showing the high input drops.  The overal load of
> > traffic
> > which should be routed (MLS switched) via the interface has not
> > increased or
> > decreased; all of a sudden in the last week traffic is being
> > (seemingly)
> > process switched through this SVI.
> >
> > Where do I begin troubleshooting high interface drops on an SVI?
>
_______________________________________________
cisco-nsp mailing list  cisco-nsp at puck.nether.net
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/