[c-nsp] Priority Queue not working

[Sean Watkins]

Hi,

Have an interesting problem (Tac case 602841205) 

I have an atm interface which can do 40 MB/s. I have a service policy setup
on a pvc, in which I wish to have 2 best effort traffic classes and a
priority class setup to give 20 Mbits/s to DSCP mark'd traffic.  One of the
best effort classess I wish to give about 10 MB/s to
(LittleBetterThanBestEffort)


For whatever reason, the DSCP marked traffic uses about max 2 Mbits/s but
drops constantly.

The service policy looks like this:

policy-map TestPolicy
  class DSCP
   priority 20000
  class LittleBetterBestEffort
   bandwidth 10000
   queue-limit 4096
  class class-default
   fair-queue
   queue-limit 4096

Any idea why?


Here is a dump of the policy in action -

LabRouter#show policy-map int atm3/0.60 output 
 ATM3/0.60: VC 60/10 -

  Service-policy output: TestPolicy

    Class-map: DSCP (match-any)
      42336285 packets, 8843163405 bytes
      30 second offered rate 1387000 bps, drop rate 0 bps
      Match: ip dscp ef (46)
        42012758 packets, 8780449692 bytes
        30 second rate 1377000 bps
      Match: ip dscp cs3 (24)
        0 packets, 0 bytes
        30 second rate 0 bps
      Match: ip dscp af31 (26)
        323526 packets, 62712653 bytes
        30 second rate 11000 bps
      Queueing
        Strict Priority
        Output Queue: Conversation 264 
        Bandwidth 20000 (kbps) Burst 500000 (Bytes)
        (pkts matched/bytes matched) 38984595/8143008816
        (total drops/bytes drops) 163665/34070735

    Class-map: LittleBetterBestEffort(match-all)
      275724261 packets, 145278876007 bytes
      30 second offered rate 21086000 bps, drop rate 0 bps
      Match: access-group name LittleBetterBestEffort
      Queueing
        Output Queue: Conversation 265 
        Bandwidth 10000 (kbps) Max Threshold 4096 (packets)
        (pkts matched/bytes matched) 230274349/117528284694
        (depth/total drops/no-buffer drops) 0/91405/205

    Class-map: class-default (match-any)
      176695535 packets, 91034822328 bytes
      30 second offered rate 3617000 bps, drop rate 0 bps
      Match: any 
      Queueing
        Flow Based Fair Queueing
        Maximum Number of Hashed Queues 256 
        (total queued/total drops/no-buffer drops) 0/2558699/2407642
LabRouter#


Is there any reason why the DSCP class drops constantly? 

My config looks like:

!
interface ATM3/0.60 point-to-point
 description Pipe to Lab router
 bandwidth 40000
 ip address X Y
 ip pim sparse-dense-mode
 tag-switching ip
 pvc 60/10 
  vbr-nrt 44209 40704 94
  tx-ring-limit 3
  oam-pvc manage
  service-policy output TestPolicy
 !
!



Sean