Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!haven!decuac!netsys!vector!telecom-gateway From: westmark!dave@uunet.uu.net (Dave Levenson) Newsgroups: comp.dcom.telecom Subject: Re: Interactions between "retry on busy" & "return call if busy" Message-ID: Date: 22 Aug 89 02:13:01 GMT Sender: news@vector.Dallas.TX.US Organization: Westmark, Inc., Warren, NJ, USA Lines: 32 Approved: telecom-request@vector.dallas.tx.us In article , munnari!batserver.cs.uq. oz.au!anthony@uunet.uu.net (Anthony Lee) writes: ...description of deadlock resulting from two parties auto-retrying each other... > My question is why is it not possible to have the exchange watch for > such a situation and cancel either the "retry on busy" or "return call > if busy". Is it possible to view the above problem as a deadlock > situation ? It is possible if 'the exchange' serves both parties. But consider that one party may be in New York and the other in Los Angeles. What if there are three parties involved (A trying to reach B who is trying to reach C who is trying A) in three different cities? A similar deadlock may occur with call-forwarding. If two subscribers happen to simultaneously forward to each other, and someone else happens to call either of them, it could create a loop that eventually occupies all of the trunks available between the two exchanges involved. But this doesn't really happen. Here in NJ, if I have call-forwarding, and a call comes in and gets forwarded, no other calls get forwarded until the original call disconnects. Subsequent calls receive a busy signal, just as they would if my calls were not forwarded, and I had answered the origianl call myself. This makes the potential loop situation harmless. -- Dave Levenson Voice: (201) 647 0900 Westmark, Inc. Internet: dave@westmark.uu.net Warren, NJ, USA UUCP: {uunet | rutgers | att}!westmark!dave [The Man in the Mooney] AT&T Mail: !westmark!dave