cracraft@venera.isi.edu (Stuart Cracraft) (03/09/88)
On an Apple Mac II, connected to an Appletalk network wherein resides two Laserwriters, named "A" and "B" respectively (names have been changed to protect the innocent), "chooser was invoked. Then, the laserwriter icon was selected. "A" popped onto the screen immediately. We waited for "B" which has been known to take its time. Eventually, "B" also popped onto the screen. We observed longer, remaining silent and motionless the entire time, and... "B" vanished! Self-erased from the menu where it had sat with "A" for a few noble seconds. 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
rj0e+@ANDREW.CMU.EDU ("Richard A. Jones") (03/14/88)
assuming that LW-B isn't on the other side of a flaky interbridge, you might consider these scenarios: 1) improper cable length in your network creating standing waves and/or timeouts (i've had that one) 2) flakey boxes and.or connectors 3) loop in the netowork (???) i would think that anything else is quite unlikely, but I'd love to hear about it. rick
creech@thorin.cs.unc.edu (Jeff Creech) (03/14/88)
In article <4982@venera.isi.edu> cracraft@venera.isi.edu (Stuart Cracraft) writes: >On an Apple Mac II, connected to an Appletalk network wherein resides >two Laserwriters, named "A" and "B" respectively (names have been changed >to protect the innocent), "chooser was invoked. > > (Paraphrased) "B" came up and then disappeared. No other net traffic. > Stuart Yes, I've seen this before, and it can actually be helpful. You have a connection loose or a termination problem somewhere on your network. We have a very large AppleTalk (LocalTalk?) net that is hooked together by Farallon Star Controlers. We had a bad Star and witnessed the same behaviour you mentioned. Looking at the flashing LaserWriters can actually be a cheap diagnostic tool. The chooser must check each of the printers every several seconds. ----------- Jeff Creech "When the going gets weird, the weird get going." Communications Technician UNC-CH Dept. of Computer Science creech@cs.unc.edu wherever!mcnc!unc!thorin!creech (919) 962-1895 CB# 3175 - Dept of Comp Sci Chapel Hill, NC 27599-3175
brad@cayman.COM (Brad Parker) (03/15/88)
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