[c-nsp] Need help w/ output drops on 7613 WS-X6748-GE-TX

[Hank Nussbacher]

At 10:56 05/01/2011 +0100, Peter Rathlev wrote:
>Content-Transfer-Encoding: 7bit
>
>On Wed, 2011-01-05 at 11:36 +0200, Hank Nussbacher wrote:
> > We have a 7613 w/ WS-SUP720-3BXL running 12.2(18)SXF11.
> > We have a 48 port WS-X6748-GE-TX.  On one interface we
> > continue to see output drops when traffic goes above 200Mb/sec.
>[snip]
>
>Do you have QoS enabled? What does "show queueing interface Gi9/29" tell
>you?
>
>Output drops are "egress buffer overflow" drops, so technically it
>happens because the box tries to send a packet out an interface already
>in use (transmitting another packet) when there is no buffer space to
>store the packet until transmission. Micro-bursts and oversubscription
>are possible causes. Short queues exacerbate the problem. With "mls qos"
>enabled and no interface-specific adjustments you could have (too) short
>queues for the relevant traffic.

Also:

gp#sho mls qos
   QoS is enabled globally
   Policy marking depends on port_trust
   QoS ip packet dscp rewrite enabled globally
   Input mode for GRE Tunnel is Pipe mode
   Input mode for MPLS is Pipe mode
   Vlan or Portchannel(Multi-Earl) policies supported: Yes
   Egress policies supported: Yes


  ----- Module [7] -----
   QoS global counters:
     Total packets: 3592763
     IP shortcut packets: 0
     Packets dropped by policing: 140
     IP packets with TOS changed by policing: 96531
     IP packets with COS changed by policing: 1700312
     Non-IP packets with COS changed by policing: 0
     MPLS packets with EXP changed by policing: 0

  ----- Module [9] -----
   QoS global counters:
     Total packets: 7865063
     IP shortcut packets: 0
     Packets dropped by policing: 765
     IP packets with TOS changed by policing: 35559
     IP packets with COS changed by policing: 8
     Non-IP packets with COS changed by policing: 0
     MPLS packets with EXP changed by policing: 0

-Hank