[c-nsp] C6k 6708 Input drops

[Marian Ďurkovič]

On Thu, Apr 16, 2009 at 09:35:52PM +0200, Peter Rathlev wrote:
> I really hate to ask this question, since input drops/discards and micro
> bursts have been discussed so much. I just can't grasp this.
> 
> The question is: what are "input drops" that don't show up in "counters
> errors" or "queueing", but do show up in "show platform hardware
> capacity interfaces"?
> 
> Recently we started seeing "input drops" on a 6708 card in Cat6500
> running SXF. The other end is the exact samer and the connection in both
> ends is 10G LR running 5m to a DWDM circuit carrying it ~50 km. It's a
> L3 (no switchport) MPLS link.
> 
> The errors appear every twenty minutes very precisely and every time
> about 100 packets are dropped "all at once" as far as I can tell. I
> don't understand how one end could send micro bursts faster than the
> other end could send them when interfaces are similar.

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.


    M.