Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!bellcore!uunet!isis!bediger From: bediger@isis.cs.du.edu (bruce allen ediger) Newsgroups: comp.protocols.appletalk Subject: AppleTalk Phase2 confusion Message-ID: <1991Feb25.174948.29698@isis.cs.du.edu> Date: 25 Feb 91 17:49:48 GMT Reply-To: bediger@isis.UUCP (bruce allen ediger) Distribution: usa Organization: Nyx -- Public access Unix, U. of Denver, dept. of Math/CS Lines: 35 I've noticed a couple of confusing things in connection with AppleTalk Phase 2. 1. Use of network number 0. From "Inside AppleTalk", 2nd edition. pg 4-6: "The network number 0 is reserved to mean unknown; by default is specifies the local network to which the node is connected." pg 4-21: "The use of network number 0 to indicate unknow introduces some complexity for DDP clients. ... The rule to use is 'Zero matches anything.'" pg 5-25: "Remember when comparing network numbers that a destination network number of 0 will always match whatever it is being compared to." Which is it: the local network, or a wildcard symbol? 2. Hidden assumption in routing algorithm on pg 5-26, Figure 5-7. It would appear that packets entering the diagram have already been filtered on the basis on hardware address. For IEEE802.3 packets, that means that only AppleTalk Phase2 multicast packets (with 9:0:7:nn:nn:nn hardware addresses) or packets addressed specifically to the router are allowed to be routed. If this check on hardware address is not performed, a whole lot of duplicate routing will get done, since there is no other way to determine whether any given packet is going from router-to-router, or from node-to-router. Brought to you by Super Global Mega Corp .com