[c-nsp] C6k 6708 Input drops

[Antonio Soares]

I had the same type of problem weeks ago with 6704-10GE cards and i increased the input queue from the default to 2000 packets. But
even with this change, i'm still getting input drops:

+++++++++++++++++++++++
  Input queue: 0/2000/259854/259783 (size/max/drops/flushes); Total output drops: 9766
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  30 second input rate 3422174000 bits/sec, 616164 packets/sec
  30 second output rate 4781032000 bits/sec, 752303 packets/sec
  L2 Switched: ucast: 3042490 pkt, 445190705 bytes - mcast: 701412 pkt, 55025811 bytes
  L3 in Switched: ucast: 1443288206417 pkt, 1002589303485288 bytes - mcast: 0 pkt, 0 bytes mcast
  L3 out Switched: ucast: 1777516490092 pkt, 1475677965625289 bytes mcast: 0 pkt, 0 bytes
     1443204358757 packets input, 1002494751199418 bytes, 0 no buffer
     Received 755421 broadcasts (701411 IP multicasts)
     0 runts, 0 giants, 0 throttles
     18 input errors, 9 CRC, 9 frame, 0 overrun, 0 ignored
     0 watchdog, 0 multicast, 0 pause input
     0 input packets with dribble condition detected
     1777485270815 packets output, 1475594581103091 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier, 0 PAUSE output
     0 output buffer failures, 0 output buffers swapped out
+++++++++++++++++++++++

And sometimes the IGP adjacency goes down and i only can correlate with these input drops. I'm running 12.2(18)SXF15a.

I have the impression that even using the maximum value allowed won't solve the issue.

I'm now thinking about adjusting the SPD values in order to, at least, avoid the IGP issue.

Comments are appreciated.



Thanks.

Antonio Soares, CCIE #18473 (R&S)
amsoares at netcabo.pt

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Peter Rathlev
Sent: sexta-feira, 17 de Abril de 2009 15:32
To: Dhingra, Anand; Marian Ďurkovič
Cc: cisco-nsp
Subject: Re: [c-nsp] C6k 6708 Input drops

On Fri, 2009-04-17 at 12:20 +0200, Marian Ďurkovič wrote:
> Input drops on L3 interfaces include also drops seen by the RP.
> These are not happening on the physical 10GE interface, but on the
> CPU's input queue. Try looking for traffic directed to the switch
> itself (SNMP, routing protocols etc) or traffic which is being punted
> to CPU for some reason.

On Fri, 2009-04-17 at 09:41 -0400, Dhingra, Anand wrote:
> I am not sure why... but for some odd reason cisco only has a 75
> packet buffer per interface going to the CPU.

That was just the pieces of information I needed. I adjusted the hold-queue from 75 to 256 packets and the drops are now gone.

Only thing left is to find out what those bursts are that the switch punts. But I'm very glad that there was an (easy to understand)
explanation. :-)

Thank you both of you!

Regards,
Peter


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