# Be value in QOS

Jun 19th, 2009

Hi, I have 512kbs link. I have to implement qos. My CIR with ISP is 300Kbs & max burst allowed is 12 kbs in time of congestion. What would be my Be & Bc value. I am totally confused with Be value. Please help

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## Replies

johnspaulding Fri, 06/19/2009 - 19:02

Here are some quick notes for you. Hope they help...But basically you would set the BC (burst committed) value to change the TC (Timer interval). You would want to change the TC for low latency applications. You change the BC to indirectly change the TC. I think the lowest at this point is 10ms you can get.

TC - Time interval /ms

BC - Burst committed

Be - burst excess (default will be what the BC is configured)

BC/TC = CIR per second

1000ms = 1 second

tc/1000 = seconds

BC = CIR*TC/1000 - Formula to calculate to figure out what the BC can be for the CIR

TC = going to be indirectly set by the BC

Why do you need to change the BC?

- Low delay applications

BE - set for 12 kbs

CIR - 300k

BC - can set for default depends on your needs

TC - cant change but will default based off BC

use the following formula to calculate - BC = CIR*TC/1000

Rupesh Kashyap Fri, 06/19/2009 - 19:22