Rate limit using CAR

[IMRAN MANGA]

Hi,

I am trying to rate limit traffic using CAR (IP) on a pos interface and wanted to know from u guys if it really works for traffic in the incoming direction.

As far as I see it, rate limiting works well on the outgoing direction but not for the incoming traffic. I might be missing something in the config or so.

Here's the config.

rate-limit input 30000000 5625000 7500000 conform-action transmit exceed-action drop

rate-limit output 30000000 5625000 7500000 conform-action transmit exceed-action drop

I would appreciate any feedback from the experts here.

Thanks,

IM.

[frennzy]

Well, I have a general observation...rate limiting inbound seems kind of pointless. The data would already have traversed the link, no? Unless you are selling that link to someone else, I can't see why you would do it.

As an example, I can see why an ISP would do inbound rate limiting on a circuit landing on their edge router...namely so that they can charge for incremental bandwidth without having to swap hardware out all the time.

In an enterprise, I can't see it being an issue.

To answer your question, though...yes it does work...what specific problems are you seeing?

you can do a

sh interfaces (if) rate-limit

to see what is happening.

[IMRAN MANGA]

Thanks for the reply frennzy.

I know what you mean and yes one reason to implement it (besides others) is as u mentioned.

What happens is that when I have a sudden spike of incoming traffic it exceeds the configured rate and SNMP counters (MRTG graph) shows traffic more than the configured rate. The problem is that the spike is for a short while and could not issue the sh int rate-limit commmand to see what excatly did haapen at the time.

Normal traffic patterns are such that the incoming traffic is well below the configured rate.

Also I found that the OID I used for polling the interfaces, plots the traffic before the rate limiting is applied. Later I used the new OID which is supposed to plot the traffic after the rate limit is applied but still I do not see a difference and incoming traffic exceeds the configured rate.

IM.