are multicast messages used in LAN''s for anything? sorry if this question is a bit dumb, i did the usual search before asking. didnt seem to come up with anything. I''m supposed to do some sort of presentation and the tit bit of knowlege i need is if multicasting is used for peer-to-peer network gaming over a LAN. AFAIK, it seems a good idea to send one message and update all on a LAN.

Multicasting only works if everyone playing has direct access to a multicast server (ie. over the internet, your ISP runs a multicast server). So, over LAN, unless your hub/switch has multicasting capabilities, then you can''t multicast. You can however BROADCAST your data, which sends it to ever computer on the LAN.

only time i seen multicasting used is in a video conferencing demo. But still, no isp allowes multicasting.

anyway, you need to get a type D ip address for each group of multicasting address.