Path: utzoo!mnetor!uunet!husc6!bunny!cayman!brad
From: brad@cayman.COM (Brad Parker)
Newsgroups: comp.protocols.appletalk
Subject: Re: "chooser"
Message-ID: <866@cayman.COM>
Date: 15 Mar 88 03:30:22 GMT
References: <4982@venera.isi.edu>
Organization: Cayman Systems Inc., Cambridge Ma
Lines: 36

From article <4982@venera.isi.edu>, by cracraft@venera.isi.edu (Stuart Cracraft):
> As best as we can determine at this time, utterly no work was done on the
> Appletalk network at this time. It is a case of true magic, unless
> plausible reasons by "skeptics" can be offerred up here.
> 
> 	Stuart

Well. I wish it were magic ;-) Actually, the chooser is periodically 
sending out NBP lookups (broadcasts) for the selected AppleTalk device
(in this case, the LaserWriter). At adds new devices as they respond
to the lookup and deletes old devices which have not responded
recently.

I suspect you have some marginal appletalk connection(s) on your net. A net
which is "lossy" (sp?) or improperly terminated will generate reflections
on the wire which cause packets to get garbled (lost). In this situation
some nodes can not consistantly communicate with other nodes. Sometimes
it works, sometimes it does not.

Running the developer program "peek" might show a lot of packets with
overruns and/or other errors.

I have seen this cause situations where one node can communicate with
only a subset of the avaiable destinations on the net. Seems to be
some sort of wave length / reflection  / cancelation related phenomena.
(disbelievers/heathens feel free to chime in here ;-) I generally shake
my beads and sprinkle some rust from an old ski binding at this point).

("air speed 70 knots - yank the stick back - jam in full left rudder")

-brad
-- 

Brad Parker
Cayman Systems		"You are sleeping; you don't want to believe..."
brad@Cayman.com			   - from a (yet another) Smith's tune