Problem:

How to apply rate limit in interface using Qos



Solution:


QOS feature that performs rate-limiting and packet classification is called CAR-Committed Access Rate.

Here is a quick tip that limits an Internet based traffic
(primarily http and FTP) to 512K, with a nice, fat burst.

First create the access lists.
access-list 100 permit tcp any any eq www
access-list 100 permit tcp any any eq ftp

Then apply rate limiting rules to the appropriate interface:
interface Serial1/0
bandwidth 2048
ip address 172.16.100.2 255.255.255.252
rate-limit input access-group 100 512000 1024000 2048000 conform-action transmit exceed-action drop
rate-limit output access-group 100 512000 1024000 2048000 conform-action transmit exceed-action drop

It will limit only http and ftp trafic, for other corporate web applications running on different ports, it will still get full E1 bandwidth.
Warning:-If, in a rate-limit rule, you reference an access list that does not exist, the rule will match all traffic. Usually not good.