Friday, October 17, 2008

Multicast Routing - Part IV Limiting Bandwith Part I

Following on from Multicast Routing Part III i now look at how multicast streams can be controlled to limit bandwidth utilisation.

For multicast streams i implement a policy that limits bandwidth consumption to 100k.

First i define my acl.

access-list 20 permit

Then i make use of the rate-limit function to control this streams network utilisation

#int fa0/0
config-if# ip multicast rate-limit out group-list 20 out

To prevent unnecessary bandwidth utilisation caused by multicast feeds looping around the network i can also set a multicast ttl threshold on the interface. For example to ensure no multicasts are sent when there ttl drops below 10 i can enter the following command.

#int fa0/0
config-if#ip multicast rate-limit 9

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