[c-nsp] QoS help on 2821

[Mark Boolootian]

Hi folks,

I'm trying to understand the behavior of what I think is a very
simple QoS configuration and am hoping someone can explain the
behavior I'm seeing and tell me what I'm doing wrong.

I have a 2821 running 12.4(22)T with the following policy map:

  class-map match-all bearer
   match ip dscp ef 
  class-map match-all signal
   match ip dscp cs3 

  policy-map voice-policy
   class bearer
      priority percent 15
   class signal
      bandwidth percent 10
   class class-default
      fair-queue

This policy map is applied as an outbound service policy on a T-1 interface.

I flood the T-1 with 10 Mb/s of unmarked UDP traffic while I have a
couple of pings running that are sending CS3 and EF marked ICMP echo
requests to a device on the far end of the T-1.  I expected the marked
traffic to make it through unscathed (modulo some additional serialization
delay introduced by the unmarked traffic), but it was all dropped (policy
map stats below).  The stats claim  bandwidth exceeded drops in the case of
the priority queue, but I'm sending a 64 byte ICMP echo request once
per second, so that seems unlikely.

CPU is basically idling on the 2821.  There are no input queue drops.

Clues?

---

dev#sh policy-map int ser 0/0/0:0
 Serial0/0/0:0 

  Service-policy output: voice-policy

    queue stats for all priority classes:
      Queueing
      queue limit 64 packets
      (queue depth/total drops/no-buffer drops) 0/131/131
      (pkts output/bytes output) 3027/266376

    Class-map: bearer (match-all)
      3158 packets, 277904 bytes
      5 minute offered rate 1000 bps, drop rate 1000 bps
      Match: ip dscp ef (46)
      Priority: 15% (230 kbps), burst bytes 5750, b/w exceed drops: 131
      

    Class-map: signal (match-all)
      1627 packets, 143176 bytes
      5 minute offered rate 1000 bps, drop rate 1000 bps
      Match: ip dscp cs3 (24)
      Queueing
      queue limit 64 packets
      (queue depth/total drops/no-buffer drops) 0/97/97
      (pkts output/bytes output) 1530/134640
      bandwidth 10% (153 kbps)

    Class-map: class-default (match-any)
      168667 packets, 213899049 bytes
      5 minute offered rate 3052000 bps, drop rate 1629000 bps
      Match: any 
      Queueing
      queue limit 64 packets
      (queue depth/total drops/no-buffer drops/flowdrops) 999/54745/54501/244
      (pkts output/bytes output) 114068/135442123
      Fair-queue: per-flow queue limit 16