Cisco – Understand the output of “sh policy-map int” in Cisco IOS

ciscoqos

I have a following CBWFQ configuration:

!
ip access-list extended GRE-traffic-ACL
 permit ip host 10.10.11.2 host 10.10.11.1
!
!
class-map match-all GRE-traffic
 match access-group name GRE-traffic-ACL
!
policy-map prioritize-GRE-traffic
 class GRE-traffic
  priority 500
policy-map traffic-policer
 class class-default
  shape average 19500000
  service-policy prioritize-GRE-traffic
!

Policy-map traffic-policer is applied to Fa0/1 interface in outgoing direction. Now if I execute sh policy-map interface Fa0/1 command, I see the following output:

r3#sh policy-map interface Fa0/1
 FastEthernet0/1 

  Service-policy output: traffic-policer

    Class-map: class-default (match-any)
      545169 packets, 822918951 bytes
      30 second offered rate 7706000 bps, drop rate 5871000 bps
      Match: any 
      Queueing
      queue limit 64 packets
      (queue depth/total drops/no-buffer drops) 0/415024/0
      (pkts output/bytes output) 130144/195409677
      shape (average) cir 19500000, bc 78000, be 78000
      target shape rate 19500000

      Service-policy : prioritize-GRE-traffic

        queue stats for all priority classes:

          queue limit 64 packets
          (queue depth/total drops/no-buffer drops) 0/0/0
          (pkts output/bytes output) 890/49840

        Class-map: GRE-traffic (match-all)
          890 packets, 43610 bytes
          30 second offered rate 0 bps, drop rate 0 bps
          Match: access-group name GRE-traffic-ACL
          Priority: 500 kbps, burst bytes 12500, b/w exceed drops: 0


        Class-map: class-default (match-any)
          544279 packets, 822875341 bytes
          30 second offered rate 7706000 bps, drop rate 5870000 bps
          Match: any 

          queue limit 64 packets
          (queue depth/total drops/no-buffer drops) 0/415024/0
          (pkts output/bytes output) 129254/195359837
r3#

1) Am I correct that "30 second offered rate" is a bandwidth which comes into service-policy named traffic-policer?

2) Why there are two lines "shape (average) cir" and "target shape rate"?

3) Am I correct that this part:

queue stats for all priority classes:

  queue limit 64 packets
  (queue depth/total drops/no-buffer drops) 0/0/0
  (pkts output/bytes output) 190/10640

..is only for GRE-traffic traffic-class as it is the only one with priority configuration?

4) Am I correct that this 19.5Mbps(shape average 19500000) is shared between all the traffic classes specified in child service-policies? class-default and GRE-traffic in my case.

Best Answer

1) Am I correct that "30 second offered rate" is a bandwidth which comes into service-policy named traffic-policer?

30 second offered rate is based on load-interval command, you can change it under interface configuration. Default is 5 minutes. 

Router(config)# interface FastEthernet 0
Router(config-if)# load-interval 30

It is a length of time for which are data used to compute load statistics. So simply said, you can imagine it as the average traffic for 30 sec interval.

And the all traffic which is processed by policy-map traffic-policer is specify above that line in class class-default (545169 packets, 822918951 bytes)

2) Why there are two lines "shape (average) cir" and "target shape rate"?

This is really good question. Many people are confused, I think that it has something in common that Cisco does not have a good explanation about it in any book.

You will never see different values between Shape average and target shape as long as you use shape average command. In case you will configure your shaping map by shape peak command instead of shape average your shaper will starts to use PIR instead of CIR.

What PIR means? How will change it your shaping? That's quite long story. I am apologize but I am not going into any explanations but you can find answer to your questions here: http://blog.ine.com/2008/08/26/understanding-the-shape-peak-command/

3) Am I correct that this part:

queue stats for all priority classes: queue limit 64 packets (queue depth/total drops/no-buffer drops) 0/0/0 (pkts output/bytes output) 190/10640

..is only for GRE-traffic traffic-class as it is the only one with priority configuration?

These are statistics for priority low latency queues. And you're right. As long as you use only one class (GRE-traffic) configured as priority, statistics are recorded only from mentioned traffic.

4) Am I correct that this 19.5Mbps(shape average 19500000) is shared between all the traffic classes specified in child service-policies? class-default and GRE-traffic in my case.

You're indeed right, CIR 19.5Mbps is shared by all child classes that you're configured in policy-map prioritize-GRE-traffic.

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