[c-nsp] troubleshooting SVI input drops on MSFC3

[barney gumbo]

I see ICMP redirects (which is not disabled on that SVI) and they are
incrementing.  I can understand high CPU as a result of the router being
forced to trx alot of ICMP redirects, however that (the MSFC sending ICMP
redirects) doesnt cause the traffic to be process-switched, does it?

ICMP statistics:
  Rcvd: 0 format errors, 0 checksum errors, 0 redirects, 318 unreachable
        10817442 echo, 3142088 echo reply, 0 mask requests, 0 mask replies,
0 quench
        0 parameter, 0 timestamp, 0 info request, 0 other
        0 irdp solicitations, 0 irdp advertisements
  Sent: 115887 redirects, 2262 unreachable, 3144305 echo, 10817442 echo
reply
        0 mask requests, 0 mask replies, 0 quench, 0 timestamp
        0 info reply, 1740292 time exceeded, 0 parameter problem
        0 irdp solicitations, 0 irdp advertisements


ICMP statistics:
  Rcvd: 0 format errors, 0 checksum errors, 0 redirects, 318 unreachable
        10820192 echo, 3142088 echo reply, 0 mask requests, 0 mask replies,
0 quench
        0 parameter, 0 timestamp, 0 info request, 0 other
        0 irdp solicitations, 0 irdp advertisements
  Sent: 115939 redirects, 2262 unreachable, 3144305 echo, 10820192 echo
reply
        0 mask requests, 0 mask replies, 0 quench, 0 timestamp
        0 info reply, 1740292 time exceeded, 0 parameter problem
        0 irdp solicitations, 0 irdp advertisements


On 5/9/07, Church, Charles <cchurch at multimax.com> wrote:
>
> 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?
> >
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