cisco 3750 rate limit

mnour401917_2 · ‎08-16-2010

Hi All,

Any idea if I can do rate limiting on Cisco 3750 switch port for egress traffic based on application or DSCP marking?

I can only apply input policy on the switch ports but not an output policy to rate limit applications or internet traffic.

I have searched netpro first and some people suggested to use “srr-queue bandwidth” but it is not clear to me how to use it to specify specific applications or network subnets.

Any help will be much appreciated.

Thanks

Mohammed

Siddharth Chandrachud · ‎08-20-2010

Hello,

a. We cannot do class based egress rate-limiting on 3750.

The only way to do egress rate-limiting is using: 'srr-queue bandwidth limit' command.

For e.g:

Switch(config)# interface gigabitethernet 1/0/2

Switch(config-if)# srr-queue bandwidth limit 70

When you configure this command to 70 percent value, the port is idle 30 percent of the time.

The line rate drops to ' 70 %' of the speed on a gig port i.e 1000 mbps by default down to 700 Mb/s.

b. These values are not exact because the hardware adjusts the line rate in increments of six.

So putting a odd value like 53 or 67 is not recommended.

Also we cannot configure this on the 10-Gigabit interfaces.

c. However, remember this rate-limiting applies to all traffic on the port.

We cannot selectively do rate-limiting for only a certain class of traffic like we can for ingress rate-limiting.

d. Use the following link for reference:

http://tools.cisco.com/squish/2dA0f

Sid Chandrachud

Cisco TAC