# Policing and bursting

Member Posts: 426
Hi All,

I am having some trouble understanding some policing issues.
Lets assume i have a CIR of 64000. As I understand it, policing refills the buckets with a pro-rated amount of bytes depending on arrival time. Thats all great. What I dont understand is the role of the Bc and Be.. Lets say i set the Bc to 1500 (bytes), that averages out to 12000 bits. So if I state just police 64000 1500, for me, it seems that no matter what, each second I can burst no more than 1500 bytes and everything else will be non-conforming?

Hope someone can help out with this!
Thanks!
Studying for CCNP (All done)

• Member Posts: 785
You already know what CIR is so if you divide that by a time interval Tc you will get Bc. You know that you can police a link below what it is clocked at so if you want to burst above CIR but at or below the access rate that is what Be should be set as. Also Be can be if you haven't used all of your Bc then in you next Tc you can use Bc and Be. Have you read QOS exam cert guide it explains traffic shaping and policing.
Studying for CCIE and drinking Home Brew
• Member Posts: 426
kryolla wrote: »
You already know what CIR is so if you divide that by a time interval Tc you will get Bc. You know that you can police a link below what it is clocked at so if you want to burst above CIR but at or below the access rate that is what Be should be set as. Also Be can be if you haven't used all of your Bc then in you next Tc you can use Bc and Be. Have you read QOS exam cert guide it explains traffic shaping and policing.

Time interval (Tc) doesnt have the same role as it does in shaping. Bucket is refilled by packet arrival times, with a rate determined by the CIR. So depending on the rate, you could have your bursting (Bc) full at all times in which case, I *think* that your constant bursting will be Bc all the time....
Studying for CCNP (All done)