UDP Multicast over the internet?

Question

I\'m not sure how best to approach my problem. I have a service with runs on a remote machine with receives and process UDP packets. I want the service to be able to re-send

Answer 1

In general this is not possible since multicast packets aren't routed.

There are some techniques to work around this (DVMRP, MOSPF and others) but they all require that you can configure all the routers between your server and the clients (or create a tunnel). There are backbone networks (Abilene, Mbone) with multicast support, but those are of most interest for universities and such. The normal consumer's internet does not have multicast.

Unfortunately you need point-to-point communication. But you are in good company, internet, radio and TV all do point-to-point, transmitting the same data numerous times. Quite a waste of bandwidth.

Answer 2

The preferred method is to use overlay multicast, i.e. use TCP links between peers and implement multicast semantics above that.

Many IPv4 routers do not support multicast or have it disabled, IPv6 is mandated to support multicast and broadcast semantics have been removed.