Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!apple!cremer
From: cremer@Apple.COM (Mike Cremer)
Newsgroups: comp.protocols.appletalk
Subject: Re: AppleTalk Phase2 confusion
Message-ID: <12359@goofy.Apple.COM>
Date: 1 Mar 91 22:13:33 GMT
References: <1991Feb25.174948.29698@isis.cs.du.edu>
Distribution: usa
Organization: Apple Computer Inc., Cupertino, CA
Lines: 32

In article <1991Feb25.174948.29698@isis.cs.du.edu> bediger@isis.UUCP
(bruce allen ediger) writes:
> I've noticed a couple of confusing things in connection with AppleTalk
> Phase 2.
> 1. Use of network number 0.
> Which is it: the local network, or a wildcard symbol?

Well, it is both.  The reason for allowing "wildcard" matching is
that this allows nodes on extended network cables with different
"network" addresses to talk to each other as if they were local
(i.e. no routing).  Consider an NBP lookup broadcast to the "local"
cable (network 0x0000), which everyone should accept.  Suppose that the
sender is on network 0x1001, and the cable has the network range
0x1000-100F.  It is likely that the nodes on the cable will be
evenly distributed among network numbers, so even though they share
the same physical cable, they are logically not peers.  If the lookup packet
was sent with the node's "real" network number (0x1001) then the packet
would only be accepted by nodes having the same network number, and none
of the other nodes (even though they should).
If, however, the lookup packet was addressed to network 0x0000, all nodes
on the cable would receive and accept the lookup request.

did any of that make any sense?

> 2. Hidden assumptions in routing algorithm

I don't follow what the question is (why lots of duplicate packets?), so
I will pass it by.

$mike cremer
apple network systems development
usual disclaimers