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Policer and burst size

Hi everybody

Please consider the following example

 

 R1 f0/0----- network

We apply an outbound policer on f0/0 :

R1 f0/0

policer 10 MIG  burst size 1000  ( bits) ,exceed drop

Assume a packet of 1200 bits need to be send out of f0/0, ( ignoring layer 2 framing just to keep things simple)

Will R1 send 1000 bits in first burst ( that is all we can send in single burst) and then send rest of 200 bits in second burst ? or Will R1 simply drop packet because not all 1200 bits can not be sent in a single burst ?

 

Much appreciated

 

 

1 ACCEPTED SOLUTION

Accepted Solutions
Cisco Employee

Hi, In policer we have

Hi,

 

In policer we have concept of Bc, Tc and CIR. So we divide 1 second into multiple Tc time period and during that Tc time period router can send Bc amount of traffic. And when you add all Bc amount of traffic sent within 1 sec that comes equal to CIR defined.

 

CIR = Bc/Tc

 

So Bc is amount of traffic which can be sent in Tc duration. but average rate over a period  would be equal to CIR. In your case first 1000 bits would be sent in first Tc time period and next 200 bits will be sent in next Tc time period.

 

Regards,

Akash

 

1 REPLY
Cisco Employee

Hi, In policer we have

Hi,

 

In policer we have concept of Bc, Tc and CIR. So we divide 1 second into multiple Tc time period and during that Tc time period router can send Bc amount of traffic. And when you add all Bc amount of traffic sent within 1 sec that comes equal to CIR defined.

 

CIR = Bc/Tc

 

So Bc is amount of traffic which can be sent in Tc duration. but average rate over a period  would be equal to CIR. In your case first 1000 bits would be sent in first Tc time period and next 200 bits will be sent in next Tc time period.

 

Regards,

Akash

 

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