Path: utzoo!utgpu!water!watmath!clyde!rutgers!cmcl2!husc6!bunny!cayman!brad@cayman.com From: brad@cayman.com (Brad Parker) Newsgroups: comp.protocols.appletalk Subject: Re: 254 node limit on ethernet problem (clarified) Message-ID: <899@cayman.COM> Date: 27 Mar 88 23:42:33 GMT References: <8803211809.AA13259@scgvaxd.SCG.HAC.COM> Sender: brad@cayman.COM Reply-To: brad@cayman.com (Brad Parker) Organization: Cayman Systems, Inc. Lines: 36 In-reply-to: morgan@jessica.stanford.EDU In article , morgan@jessica writes: > >Regarding the 254 node limit on an AppleTalk network: >... >A proper fix involves some real >violence to the existing AppleTalk scheme. They admitted that >AppleTalk has outgrown its original design goals (as have IP and >DECNet, to name two others), and some hard thinking has to be done >about where it goes from here. I think the implication is that the >fix to this problem would only come along with a top-to-bottom >redesign. > While I totally agree that it make more sense to break up your ethernets, I not sure I understand this statement. It seems that ethertalk nodes could be made "aware" of multiple logical AppleTalk networks on one single ethernet to short-circuit the standard "packet-bound-for-another- network-send-it-to-the-bridge" code. (sorry - I was just hacking some lisp code for nntp/gnews). I.e. it seems that AARP could be changed slightly (or perhaps not at all) to use the 24 unused bits (16 for a network number come to mind). Then all that is needed is a slight change to the code in MLAP to consult a local table of "logical" networks on the local wire. If the network is not in the table, then the packet get's send (as it would be now) to a bridge. (a discusting hack which might work now would be to hack AARP to include networks and then set up a "psuedo bridge" on the ethernet which would retransmit packets sent to it; the psuedo bridge would know which nets where local and which where not.) If my notions are completely wrong, please let me know. Sometimes I have flashbacks ;-) -brad