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Reaching the Masses - IP Multi-Cast

One of the less understood features of TCP/IP is IP multicast. While normal TCP/IP routing allows exactly two network nodes (a sender and a receiver) to talk to each other, multicasting allows a sender to reach several recipients with only one target address and the same sequence of packets.

I will concentrate on IPv6 and Linux in these descriptions. Where appropriate I will add a few comparisons for IPv4, but will not repeat all that has been said in other articles and howtos. Other Unixoid systems (Solaris, the BSDs, MacOS/X) should require very little porting effort of what is said here. While Windows can act as a multicast client in most protocols, the changes to examples and sources would be too extensive to easily support it.

To follow my examples you'll need my multicast ping utility, you can get it via subversion and compile it with a simple call to GNU make:

sh$ svn checkout
sh$ cd muppet
sh$ gmake

There are three parts to this article, depending on what you want to do you may want to read just one or all of them:

There is also some auxilliary information that may be of interest:

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