Subject: Re: Something different: Multicast performance factors

From: [email-masked] (Kevin Dubray)
Date: Tue, 17 Mar 1998 08:58:50 -0500

>From [email-masked] Tue Mar 17 08:45:41 1998

[ original posting on idmr ]

> If you think that there are other considerations that distinguish multicast 
> from unicast benchmarks, please drop a note.  

one item that is missing from your draft is the degree of fan-in
and (or more importantly) fan-out of an on-tree node. by this i mean 
that if a downstream node has a high degree of fan-out, then this
tends to have a corresponding compression of branches that comprise
the tree. which in turn leads to less over-all state in the system.

as an example, if i have a tree whose root starts in the U.S. and
has receivers in europe, then it may be desireable to have one branch
span the atlantic ocean (e.g., New York to London) and then have
that node be the distribution point for other EU countries. this as 
opposed to 2 or three branches (eg, new York to London, Boston to 
Stockholm) eminating from the U.S. to europe.

the tradeoff is that there will probably a bit more delay experienced
by some members, but the cost to the system is less.

-ken