On Thu, 12 Jul 2001, Dickson, Brian wrote:

...

- What is IRC, or for that matter net-news, at its heart? A transient, store-and-forward, one-to-many message system.

In otherwords, multicast re-implemented on unicast, in some cases poorly

and

...

at great cost (news).

AFAIK, there is no implemented multicasting protocol - routing and reliable

transport - that can scale to the number of groups, senders and receivers visible in current IRC networks. Source-based trees would require the order of 1E6 (S,G) pairs and core/RP-based routing would be an even easier

target for the SK's than IRC already is.

Achieving instant group messaging on a global scale with convential multicast

is unlikely. Relevant academic research continues.

J

This sounds like a good application for SSM (which is, BTW, can be made much "harder" than ASM). Send many to one to a nearby server, which sends out one to many to interested parties. This way, participants would not need their own S,G. The crucial thing would be to make it fractal (hierarchical) in nature. I agree that multicasting will become a target for SK; in many ways I think the IRC attacks are a premonition of things to come. Regards Marshall Eubanks