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rate limite

Hi friends

I have some questions:

1- does 3560 switch support rate limite?

2- do you have sample config?

3- do you know a good reference aboute it?

thanx

3 REPLIES

Re: rate limite

Hi!

What version of IOS is running on your 3560?

On it depends the compatibility of your switch with the mentioned command.

Go through the following link for your last 2 queries:

http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_command_reference_chapter09186a0080087f26.html#wp1037428

Please rate all the helpful posts.

Regards,

AbhisheK

Bronze

Re: rate limite

You can support a form of rate-limiting through the implementation of QoS. Things to remember are to disable flow control on all the switch ports (including the gig ports) and to enable qos global:

conf t

int range f0/1 - 24

no flowcontrol receive

exit

mls qos

end

Then create the class map and the policy map:

conf t

class-map match-all rate-limit

description Bandwidth Control

match ip dscp 0

end

conf t

policy-map 3meg

class rate-limit

police 3072000 576000 exceed-action drop

end

This example is for a 3Mbps rate limit with a burst that follows the formula of (rate-limit * 1.5)/8

Then apply the policy to an interface:

conf t

int f0/1

service-policy input 3meg

service-policy output 3meg

end

This example is matching based on a DSCP value of 0. This is the default for most of the traffic on a network (mainly Internet) and as such, serves as a good match. The bad thing is anything that does not have a DSCP value of 0 in the packet is not affected by this rate-limit. This can be good or bad. Phones, both call signaling and voice, are marked with values other than 0 which is good as they are not affected by this rate-limit. Some p2p programs change their DSCP value to something other than 0, and as such, will not be affected by this rate-limit. I sugest a multi-level to get what you are looking for. At the switch level, things are handled in hardware. I would try to get the most of it here at the access layer first. Then at the first layer 3 boundary, I would also have another rate-limit on the interface or sub-interface catching anything that slipped passed the first rate-limit. For more detail, cisco press has an excellent book:

End-to-End QoS Network Design

Hope this helps.

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