Friday, October 17, 2008

Rate Limiting vs Policing

Rate limiting has now been by and large superceded by MQC (Modular QOS CLI). Hence if requested to rate limit a traffic flow the chances are an MQC solution will be whats required, as ever, close attention to the question specifics is required.

In this scenario i limit the traffic flow for returning web traffic to the LAN segment on connected interface fa0/0 to 512kbps.

ip access-list extended 100
permit tcp any eq www any

class-map HTTP
match access-group 100

policy-map HTTP
class HTTP

police cir 512000

int fa0/0
config-if#service-policy output HTTP


Anonymous said...

just a small note:

When you "only" use the command police cir 512000, then IOS will calculate the "missing parameters" for you.

#show policy-map HTTP
Policy Map HTTP
Class HTTP
police cir 512000 bc 16000
conform-action transmit
exceed-action drop

If IOS would just always be that nice. :-))

richsd1 said...

Thanks for your comments. In this scenario the defaults meet the requirements, but worth pointing out they are added by the IOS, and certainly worth reviewing after the command has been applied.

As you say, if only IOS would always be so accomodating!