[c-nsp] LLQ not utilizing reserved bandwidth & packet drops in Nested policy-map (2 level hierarchial policymap)

[Arun Kumar]

Hi Velimir - Please find the full configuration of ACL, Class map and
policy map

C2800-R6-CPE1#sh class-map
 Class Map match-all EF (id 1)
   Match access-group name EF

 Class Map match-all DATA1 (id 2)
   Match access-group name DATA1

 Class Map match-all DATA2 (id 3)
   Match access-group name DATA2

 Class Map match-all DATA3 (id 4)
   Match access-group name DATA3

 Class Map match-all DATA4 (id 5)
   Match access-group name DATA4

 Class Map match-any class-default (id 0)
   Match any

C2800-R6-CPE1#sh ip acce
C2800-R6-CPE1#sh ip access-lists
Extended IP access list DATA1
    10 permit ip any host 172.9.0.10 (56100 matches)
Extended IP access list DATA2
    10 permit ip any host 10.20.0.10 (18579 matches)
Extended IP access list DATA3
    10 permit ip any host 124.7.227.17
Extended IP access list DATA4
    10 permit ip any host 124.7.227.19
Extended IP access list EF
    10 permit ip host 10.10.1.2 host 119.227.3.159 (125370 matches)
C2800-R6-CPE1#

C2800-R6-CPE1#sh policy-map child-out1
  Policy Map child-out1
    Class EF
      priority 50 (%) 16000
    Class DATA1
      bandwidth 20 (%)
    Class DATA2
      bandwidth 10 (%)
    Class DATA3
      bandwidth 10 (%)
C2800-R6-CPE1#

C2800-R6-CPE1#sh policy-map parent-out
  Policy Map parent-out
    Class class-default
      Average Rate Traffic Shaping
      cir 128000 (bps)
      service-policy child-out1


Service-policy output: parent-out

    Class-map: class-default (match-any)
      199999 packets, 45317308 bytes
      30 second offered rate 0 bps, drop rate 0 bps
      Match: any
      Queueing
      queue limit 64 packets
      (queue depth/total drops/no-buffer drops) 0/2631/0
      (pkts output/bytes output) 197368/47497736
      shape (average) cir 128000, bc 512, be 512
      target shape rate 128000

      Service-policy : child-out1

        queue stats for all priority classes:
          Queueing
          queue limit 64 packets
          (queue depth/total drops/no-buffer drops) 0/2631/0
          (pkts output/bytes output) 122667/19466406

        Class-map: EF (match-all)
          125298 packets, 18630200 bytes
          30 second offered rate 0 bps, drop rate 0 bps
          Match: access-group name EF
          Priority: 50% (64 kbps), burst bytes 19200, b/w exceed drops: 2631

The router uses the "shape average CIR" value used in parent policy map
when percentage is used in child policy map. Please see the above output
where in class-map EF has 64kbps when 50% of parent CIR 128Kbps is
configured. Tried changing the bandwidth command under the interface to
128K but still the issue persists.

Hi Jeya - The issue is LLQ should be able to burst till 64kbps during no
congestion which is not happening with default burst size of 1600 bytes
(200ms). Only when the burst size is changed to 16000bytes (2s), i am able
to burst till 64Kbps.


On Fri, Feb 21, 2014 at 2:44 PM, Jeyamurali Sivapathasundaram <
sjeyamurali at gmail.com> wrote:

> Hi Arun
>
> When no congestion, you can use more than 16K for LLQ  or any of the other
> classes. This is default behaviour.
>
> Jey
>
>
> On Thu, Feb 20, 2014 at 2:27 PM, Arun Kumar <narain.arun at gmail.com> wrote:
>
>> Hi,
>>
>> I think this issue is quite old but I could not get any conclusive
>> explanation.
>>
>> Below is the configuration:
>>
>> C2800-R6-CPE1#sh policy-map parent-out
>>
>>   Policy Map parent-out
>>
>>     Class class-default
>>
>>       Average Rate Traffic Shaping
>>
>>       cir 128000 (bps)
>>
>>       service-policy child-out1
>>
>> C2800-R6-CPE1#sh policy-map child-out1
>>
>>   Policy Map child-out1
>>
>>     Class EF
>>
>>       priority 50 (%) 16000
>>
>>     Class DATA1
>>
>>       bandwidth 20 (%)
>>
>>     Class DATA2
>>
>>       bandwidth 10 (%)
>>
>>     Class DATA3
>>
>>       bandwidth 10 (%)
>>
>> C2800-R6-CPE1#
>>
>>
>>
>> In the above configuration, parent policy has 128Kbps and Child has 4
>> Classes with Class EF is LLQ with priority of 50% bandwidth (burst size is
>> default 1600bytes), class DATA1 with 20%, class DATA2 with 10% and class
>> DATA3 with 10%.
>>
>>
>> With the above configuration, I could not able to push beyond 16Kbps of
>> traffic on class EF (LLQ). When the burst size is increased to 16000
>> bytes,
>> I am able to push around 60Kbps.
>>
>>
>> Wanted to understand this is the expected behavior of LLQ in Nested policy
>> map or I am missing something.
>>
>>
>> thanks in advance
>> _______________________________________________
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>>
>> https://puck.nether.net/mailman/listinfo/cisco-nsp
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>>
>
>
>
> --
> Best Regards,
>
> Jey S.
> Network Engineer
> London
>
>