[e2e] node addresses vs. interface addresses

[J. Noel Chiappa]

    > From: "Tim Moors" <t.moors at unsw.edu.au>

    > Perlman explains how "internal network numbers" in IPX helped avoid
    > sub-optimal routes to multihomed destinations

Except that this is a bad idea in a very large network. In short, it's
putting the entire cost of multi-homing (one rarely gets a benefit without
some cost somewhere, neh?) into the routing, where the cost is paid by
everyone (effectively - long arcane routing point elided) across the network,
to maintain a route to that destination. This is fine in a small network,
where the total incremental cost is small, but not fine in a big one.

Yet one more example of someone-or-other's (who is it, does anyone know?)
Nth law of large systems, that where you have two functions which are
performed by a single mechanism in a small system, they will each need a
separate mechanism as the system gets larger.

	Noel


PS: If anyone cares about an architectural perspective on multihoming, I
have some notes on it here:

    http://ana-3.lcs.mit.edu/~jnc/tech/nsrg/multihoming_points.txt

about how to think about it.