Please explain show policy-map interface for police command

[Nashja]

Could anyone please explain the red bold fonts below :

R1# show run

< omitted >

policy-map QoS_Link

class Police_1

  police cir 20000 bc 2500 be 2500

    conform-action transmit

    exceed-action drop

class class-default

  fair-queue

< omitted >

R1# show policy-map interface s0/0.1

< omitted >

Class-map: Police_1 (match-any)

      153717 packets, 29016250 bytes

      30 second offered rate 0 bps, drop rate 0 bps

      Match: access-group name EPP

        153717 packets, 29016250 bytes

        30 second rate 0 bps

      police:

          cir 20000 bps, bc 2500 bytes

        conformed 145527 packets, 20736043 bytes; actions:

          transmit

        exceeded 8190 packets, 8280207 bytes; actions:

          drop

       conformed 0 bps, exceed 0 bps

< omitted >

What do the red bold fonts mean?

Thank you.

Nash

[cadet alain]

this means that for load-interval configured on your interface which should be 5 mins by default you had 0 bps  of traffic conforming to your policing and 0 bps exceeded.

[Nashja]

Thank you cadetalain and could you please tell me how can I show dropped packets from this police command.

Thank you.

Nash

[cadet alain · Accepted solution]

You can see it here:

exceeded 8190 packets, 8280207 bytes; actions:
 drop

[Nashja]

Hi cadetalain,

     I think your answer may be incorrect. Please see information below:

Field	Description
exceeded, packets, bytes, actions	Displays the number of packets (also shown in  bytes) marked as exceeding a specified rate and the actions taken on the  packet. If there are multiple actions, each action is listed  separately.

and

Token Bucket Algorithm with One Token Bucket

The one token bucket algorithm is used when the violate-action option is not specified in the police command CLI. The conform bucket is initially set to the full size (the full size is the number of bytes specified as the normal burst size). When a packet of size B bytes arrives at time t the following actions occur: a. Tokens are updated in the conform bucket. If the previous arrival of  the packet was at t1 and the current time is t, the bucket is updated  with (t-t1) worth of bits based on the token arrival rate. The token  arrival rate is calculated as follows: (time between packets * policer rate)/8 bytes b. If the number of bytes in the conform bucket - B is greater than or  equal to 0, the packet conforms and the conform action is taken on the  packet. If the packet conforms, B bytes are removed from the conform  bucket and the conform action is completed for the packet. c. If the number of bytes in the conform bucket - B is less than 0, the exceed action is taken.

Reference

http://www.cisco.com/en/US/docs/ios/12_1t/12_1t5/feature/guide/dtpoli.html

http://www.cisco.com/en/US/docs/ios/12_3/qos/command/reference/qos_s2g.html#wp1146884

Refer my configuration above, If router receives packets more than conform bucket ( 20k )  then they will move to exceed bucket ( 2.5k ). If router still receives packets more than exceed bucket limitation ( 2.5k ) then drop action is taken.

I would like to know how can I check dropped packets? and the answer for my first question may be incorrect because I tried to show policy-map interface yesterday, the result from shown command as follows :

R1# show policy-map interface s0/0.1

< omitted >

    Class-map: Police_1 (match-any)

      161696 packets, 30641154 bytes

      30 second offered rate 2000 bps, drop rate 0 bps

      Match: access-group name EPP

        161696 packets, 30641154 bytes

        30 second rate 2000 bps

      police:

          cir 20000 bps, bc 2500 bytes

        conformed 153011 packets, 21870567 bytes; actions:

          transmit

        exceeded 8685 packets, 8770587 bytes; actions:

          drop

       conformed 2000 bps, exceed 1000 bps

< omitted >

Thank you.

Nash

[Jon Marshall · Accepted solution]

Nash

Refer my configuration above, If router receives packets more than conform bucket ( 20k )  then they will move to exceed bucket ( 2.5k ). If router still receives packets more than exceed bucket limitation ( 2.5k ) then drop action is taken.

You have not specified a "violate-action" and so your policing is using a one token bucket. This means that anything that does not conform is an exceed packet and will be dropped. If you want to use an exceed bucket as well then you need to use a two token bucket algorithm and to do this you need to specify a "violate-action" in your policy-map.

Jon

[Nashja]

Hi Jon,

     Ohh, I see. Thank you Jon.

Hi Cadetalain,

     Sorry for my misunderstanding.

[Florin Barhala]

Hi guys,

Digging through answers, if someone can clear this for me:

A: police cir 20000 bc 2500 be 2500

B: If router receives packets more than conform bucket ( 20k )  then they will move to exceed bucket ( 2.5k ). If router still receives packets more than exceed bucket limitation ( 2.5k ) then drop action is taken.

As far as I know the conform-bucket equals Bc_value. So for A_section, the conform bucket is equal to 2500 bytes, right?

For the values from A_section what is the Tc equal to? Is it 2500/20000 --> 0.125ms or 2500/ (20000/8) = 1s ?

I read on web that Tc value has some restrictions; is this true for Frame Relay environments only?

I read some explanation from Cisco website still I am confused if:

- Tc value is still used

- and the conversion between CIR which is expressed in bits and Bc/Be which goes to bytes