[c-nsp] POS Output Queue Drops

[Bruce Pinsky]

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Richard Hicks wrote:
> I have 2 new POS OC3 circuits to different ISP's.  I am running little
> traffic over these links currently (Average 10mbit out, peaking to
> 20mbit).  But I am seeing output queue drops on both circuits.
> 
> Both are 7206VXR's with NPE-G2 running 12.4(4)XD2.
> 
> According to Cisco documentation I should only get output drops if the
> circuit is full or can't handle a traffic burst.  I don't think either
> of these applies to me.
> 
> Any ideas on why I am seeing these output queue drops?
> 

Might not be switched traffic but rather some control plane packets
generated by the processor.  Check for buffers misses (sh buffer) as one
starting point.  What routing protocol(s) are running over that interface?

> Router1#show int pos 1/0
> POS1/0 is up, line protocol is up
>   Hardware is Packet over Sonet
>   Description: OC3 POS
>   Internet address is xxx.xxx.xxx.xxx/30
>   MTU 4470 bytes, BW 155000 Kbit, DLY 100 usec,
>      reliability 255/255, txload 6/255, rxload 2/255
>   Encapsulation PPP, LCP Open
>   Open: IPCP, CDPCP, crc 16, loopback not set
>   Keepalive set (10 sec)
>   Scramble disabled
>   Last input 00:00:02, output 00:00:00, output hang never
>   Last clearing of "show interface" counters 1w4d
>   Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 11785
>   Queueing strategy: fifo
>   Output queue: 0/40 (size/max)
>   5 minute input rate 1404000 bits/sec, 525 packets/sec
>   5 minute output rate 3652000 bits/sec, 870 packets/sec
>      364062953 packets input, 2013742986 bytes, 0 no buffer
>      Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
>               0 parity
>      0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
>      742407543 packets output, 2729543042 bytes, 0 underruns
>      0 output errors, 0 applique, 0 interface resets
>      0 output buffer failures, 0 output buffers swapped out
>      0 carrier transitions
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