[c-nsp] 6704-10GE huge input drops (flushes)

[Antonio Soares]

The ibc values I see now (normal behavior):

cat6k#show ibc | inc packets  
        5 minute rx rate 65000 bits/sec, 94 packets/sec
        5 minute tx rate 27000 bits/sec, 35 packets/sec

Show ibc from show tech captured two hours after the first occurrence:

Interface information:
        Interface IBC0/0(idb 0x50ECB7A8)
        Hardware is Mistral IBC (revision 5)
        5 minute rx rate 323000 bits/sec, 89 packets/sec
        5 minute tx rate 37000 bits/sec, 29 packets/sec
        5868647586 packets input, 801582284787 bytes
        1350630188 broadcasts received
        3458894285 packets output, 636391923013 bytes
        1580035101 broadcasts sent
        0 Inband input packet drops
        0 Bridge Packet loopback drops
        973954452 Packets CEF Switched, 11041138 Packets Fast Switched
        0 Packets SLB Switched, 0 Packets CWAN Switched
        IBC resets   = 1; last at 06:30:38.772 UTC Thu Jan 13 2011

I was convinced that the flushes had to do with Hw. What happens with these
counters when we have bursts of traffic ?
Is it possible to a have a burst of traffic impacting the bgp/igp
adjacencies ?


Regards,

Antonio Soares, CCIE #18473 (R&S/SP)
amsoares at netcabo.pt
http://www.ccie18473.net



-----Original Message-----
From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Saku
Ytti
Sent: terça-feira, 7 de Maio de 2013 07:38
To: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] 6704-10GE huge input drops (flushes)

On (2013-05-06 23:59 +0100), Antonio Soares wrote:

>   Input queue: 0/2000/15863293/15863293 (size/max/drops/flushes); 
> Total

> I was thinking about bursts or micro-bursts but when this happened, 
> the bgp/isis sessions that go over this link went down.

> But it makes some sense because the 6704 does full-rate and the 
> 6708/6716 are oversubscribed (more buffering capacity needed).

These counters have nothing to do with HW, they are from SW path. You're
either SW switching or getting some trash to control-plane.

You could do netdr or pinnacle or RP/SP ERSPAN capture to see what packets
are hitting control-plane

First step would be to compare 'show ibc | i packets/sec' between other box
which does not suffer from this, to confirm that packet rates are
unexpectedly high.

--
  ++ytti
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