Bandwidth Rate Limit for particular interface

k.hariharan1 · ‎06-02-2009

hi,

i have 7000 series Cisco router with STM-1 controller , we have configured STM-1 controller for 63 E1 link and one customer needs only 1mb link so instead of changing the controller configuration i decided to configure rate limit command under specific interface which is connected to that particular customer. my config is as follows

rate-limit output 1536000 288000 288000 conform-action continue exceed-action drop

before configuring this i would like to know whether its correct or not and a brief explanation about this command.

Regards,

Hariharan K

Giuseppe Larosa · ‎06-02-2009

Hello Hariharan,

conform-action should be transmit or any other variation of it.

the continue option means looks for other CAR statements (nested CAR) but if no other action follows the behaviour can be different then what you would like.

under the STM controller the continue option can be correct

Hope to help

Giuseppe

k.hariharan1 · ‎06-03-2009

hi Giuseppe,

i would like to give 1.5mb link to that customer but in my stm-1 controller default configuration. each e1 is = 2mb

after that rate limit what does that 3 values stands for and how can i calculate it

your reply is much appreciated

Regards,

Hariharan k

Giuseppe Larosa · ‎06-03-2009

Hello Hariharan,

the parameters have the following meaning:

first is the committed rate

second is the normal burst size

third is the excess burst size.

usually they are deployed as an equivalent time at peak rate.

They are buffers used to handle some packets and burstiness on the traffic.

if the third is greater then the second initially a bigger burst can be supported.

here it is a link to command reference

http://www.cisco.com/en/US/docs/ios/qos/command/reference/qos_q1.html#wp1015612

that provides also the suggested formula for buffer dimensioning:

normal burst (in bytes) = configured rate (in bits per second) * (1 byte)/(8 bits) * 1.5 seconds

Hope to help

Giuseppe