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Queue Limit - parent/child policy



Trying to understand the queue limit when using a parent/child policy

So Parent shaping the overall traffic and child doing the QOS

For example

In a config like this

policy-map PARENT
class class-default
shape average 17683258
service-policy CHILD

policy-map CHILD
class VOICE
  police 5200000 12000 12000 conform-action set-dscp-transmit ef exceed-action set-dscp-transmit ef violate-action drop
class DATA2
  bandwidth remaining ratio 101
  queue-limit 212 packets
  police 1048000 35500 71000 conform-action set-dscp-transmit af21 exceed-action set-dscp-transmit af21 violate-action set-dscp-transmit af22

class DATA1
  bandwidth remaining ratio 202
  queue-limit 300 packets
  police 2096000 50000 100000 conform-action set-dscp-transmit af11 exceed-action set-dscp-transmit af11 violate-action set-dscp-transmit af12

class class-default
  bandwidth remaining ratio 98
  queue-limit 420 packets

The Parent by default his a queue limit of 73 packets with no amendments to the config, yet the child has more. In a scenario like this is it the child configuration that takes preference?

Service-policy output: PARENT

    Class-map: class-default (match-any) 
      1342116125 packets, 632169233328 bytes
      30 second offered rate 2524000 bps, drop rate 0000 bps
      Match: any
      queue limit 73 packets <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
      (queue depth/total drops/no-buffer drops) 0/1274435/0
      (pkts output/bytes output) 1340841447/630571911337
      shape (average) cir 17683258, bc 70734, be 70734
      target shape rate 17683258


3 Replies 3

Joseph W. Doherty
Hall of Fame
Hall of Fame

This is the type of question that only Cisco might be able to answer.

I've seen such question multiple times on the forum.

Here is a cosmetic bug for this - CSCve90185

Cisco Employee
Cisco Employee

The parent policy queue-limit value can be ignored when using hierarchical queueing. Just configure the queue-limits in the child policy and ignore the parent. If using ISR G1 or G2, you must also tune the "hold-queue" parameter on the physical interface where the policy is applied. On ISR 4k or ASR 1k, this is not required.

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