On Friday 11 March 2005 01:05, Wayne Stallwood wrote:
On Thursday 10 March 2005 10:22 pm, Karl Foley wrote:
It's not a subnet, it's a whole new class off addresses. You've probably heard of class A, B and C ip addresses right? Multicast uses class D addresses. Multicast addresses range from 224.0.0.0 right up to 239.255.255.255.
(snip)
Thank you,
In a few short paragraphs you have answered a lot of questions I had about multicasting, turns out that I shouldn't actually need it for my application (TwonkyVision supports it but I don't think the MP101 needs it)
Thanks for the info though, that was really interesting. I would love to see a demo of the Videolan stuff at a ALUG meet (if you have a working and transportable setup)
Also, although multicast packets can cross routers they have a time-to-live (hop count) associated with them, so they tend to confine themselves to the local subnet and not propagate through the entire Internet.
Multicast is used for a number of things, one being to permit discovery of one machine by another without the need to publish IP addresses. You can always tell who sent a multicast packet, so if a machine announces itself when it joins the network, all the other interested parties will know it's there and respond (or not) accordingly. I had fun writing a Java peer-to-peer distributed processing application using that principle.
-- GT