About Qos

[vinodhanjv]

Dear Friends,

Please any one explain me regarding the below command out put regarding the qos. 

sai_fus#sh policy-map interface gigabitEthernet 0/2

GigabitEthernet0/2

  Service-policy output: CASTORONE-SHAPE

    Class-map: class-default (match-any)

      5876 packets, 3609368 bytes

      30 second offered rate 2924000 bps, drop rate 269000 bps

      Match: any

      Queueing

      queue limit 64 packets

      (queue depth/total drops/no-buffer drops) 987/674/292

      (pkts output/bytes output) 5207/2998686

      shape (average) cir 2550000, bc 10200, be 10200

      target shape rate 2550000

Regards,

Vinodhan.

[Joseph W. Doherty]

You're asking about the shape statements?

If so, the shape statements, try to emulate an "interface" set at the CIR rate.  I.e. your class-default traffic forwarding should behave somewhat similar to it passing out a 2.55 Mbps interface.

As the class is being "offered" 2,924,000 and its dropping 269,000, it's forwarding about 2,655,000; a little higher than the target rate of 2.55 Mbps.

[vinodhanjv]

Hi joseph,

Thanks for your info.

Please explain me regarding in details about offered rate,drop rate ,bc and be.

And also difference between shape average cir and target shape rate.

shape (average) cir 2550000, bc 10200, be 10200

      target shape rate 2550000

30 second offered rate 2924000 bps, drop rate 269000 bps

Regards,

Vinodhan.

[Joseph W. Doherty]

Offered rate is "ingress" rate to class.

Drop rate is rate of drops (of class traffic).

(NB: class "egress" rate should be offered rate less drop rate.)

Bc is burst committed (i.e. normal) amount of data (in bytes) allowed during Tc that's not shaped.  Data beyond that gets queued by shaper.

(NB: Tc = Bc / CIR)

Be is burst excess (in addition  to Bc) amount of data allowed during Te that's not shaped.  Doesn't apply when "average" shaping is used.  (Documentation varies on how Be works.  Most platforms seem to reset both Bc and Be each Tc.  Some documentation, though, has Be only recovers any left over Bc per Tc.  This would allow short term bursts.)

Believe target shape rate is just another term for CIR.