Newsgroups: comp.protocols.appletalk
Path: utzoo!utgpu!cunews!bnrgate!bwdls61!bnr.ca!bschmidt
From: bschmidt@bnr.ca (Ben Schmidt (BNR))
Subject: Re: uab+ problem.
Message-ID: <1991Mar7.134304.2637@bwdls61.bnr.ca>
Sender: usenet@bwdls61.bnr.ca (Use Net)
Organization: Bell-Northern Research
References: <1991Mar6.234858.25707@thunder.mcrcim.mcgill.edu>
Date: Thu, 7 Mar 1991 13:43:04 GMT

In article <1991Mar6.234858.25707@thunder.mcrcim.mcgill.edu> 
peta@McRCIM.McGill.EDU (Peter Whaite) writes:
> Anyway, after a while the net starts
> getting really bogged down, and the problem is that when uab+ comes up 
> it gets told (by one or both of the shivas) that there is a net 0.0.   
> It seems like the distance (number of hops?) is 132!!  I`m not sure if  
> this problem happened recently or if it has always been around as our  
> network has been in a state of flux for some time now.  New macs have   
> been added recently.  Could this be a Phase II incompatibiliy?  

Peter,

Apple retro-actively changed the ATP1 RTMP spec, when they introduced 
ATP2/Internet Router, so that the first routing tuple in an ATP1 RTMP 
packet is an RTMP version number.

To an ATP1 router, this tuple looks like net 0 at 132 hops or some such 
nonsense.  Sources of these "modified" ATP1 RTMP packets could be any 
Apple Internet Router s/w, or possibly any other ATP1/P2 transition 
gateway on your net - the Shiva's?)

In an *ideal* world, this retro-active change to the ATP1 spec would have 
caused no problems:  any other ATP1 router should just drop that 
tuple since:
  a) net 0 is an invalid net number.  (well actually, an "unknown" net)
  b) 130 exceeds the 15 hop count limit and the net associated with it 
     should be not be further propogated.

Guess you don't work in an *ideal* world either?  :-)

Retroactively changing existing protocol specs (as opposed to
introducing new ones, like ATP2) is never nice. Not advertising it, is
even less nice.

Ben Schmidt     Bell-Northern Research, Ltd.   Ph: (613) 763-3906
Information     P.O. Box 3511, Station C       FAX:(613) 763-3283
Technology      Ottawa Canada K1Y 4H7          bschmidt@bnr.ca 
