multicasting

[carl_townshend]

Can anyone please tell me what this is and why we would enable/disable this on our routers ?

thanks

[ToddWarren]

Hello,

Here's the straight forward answer to your question.

http://www.ciscotaccc.com/iprout/showcase?case=K91840212

We use it for video streaming to the enterprise utilizing RP's (rendevous points).

It's useful in directing traffic from a single point to multiple points simultaneously.

HTH's

[scottmac]

Multicasting is a method for saving bandwidth.

With multicasting, one staton "speaks" and any number can listen, if they know which address ("group") to listen in on.

If you wanted to distribute video (~3Mbps stream), for example, if each station connected as a unicast, and you had 100 stations participating, you'd need (at least) 300Mbps of bandwidth from that video server.

No big deal, just toss in a Gig link to the server, right?

Well, what if 50 of those stations were on a single LAN segment? or on the other side of of a 6Mbps Multi-Link Frame Relay WAN connection?

With multicasting, you'd only use the 3Mbps(plus a little overhead). The transmitting device assigns / is assigned a specific multicast address (a group) ... and all the other interested devices just listen for that group. One talks, everyone else listens.... much more efficient.

Good Luck

Scott