At 09:06 AM 5/23/00 +1000, Jan Mikkelsen wrote:

>Jim Starkey <jas@...> wrote:
>
>>
>>Broadcast is a LAN solution. It doesn't work on the Internet,
>>which, in my opinion, rules it out.
>
>
>Not so: IP multicast works across router boundaries and over WAN links.
>Ref. RFCs 1112, 2236, 2365. Also of interest is RFC 2357.
>

RFC 1112 outlines an IP broadcast protocol in which an IP packet
sent to a dynamic host group is broadcast to that group (IP,
for those who don't follow network technology closely is the
host to host protocol on which TCP, a virtual circuit session
protocol, UDP, user datagram protocol, are layered). Aside from
the minor issue that nobody supports it is the more serious problem
that it is unreliable -- a router is free to drop a packet on the
floor without notice to either the sender or receiver. Broadcasting
scales, but reliable broadcasting is an open question.

RFC 2357 is proposes criteria to evaluate proposals for reliable
broadcasting.

The problem domain for IP multi-casting is real time video or
audio feeds to large number of recipients, a space in which
the odd packet dropper here and there is acceptable.

Whether or not any of this leads to anything useful is interesting
but moot; our job is to define appropriate services in our problem
space with the existing technical infrastructure.

Jim Starkey