Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!utgpu!water!watnot!watmath!clyde!rutgers!seismo!rochester!ciaraldi From: ciaraldi@rochester.UUCP Newsgroups: comp.dcom.modems Subject: Re: Dial-in Modems for VAX Message-ID: <25831@rochester.ARPA> Date: Wed, 11-Mar-87 22:57:23 EST Article-I.D.: rocheste.25831 Posted: Wed Mar 11 22:57:23 1987 Date-Received: Fri, 13-Mar-87 01:11:26 EST References: Reply-To: ciaraldi@rochester.UUCP (Mike Ciaraldi) Distribution: world Organization: U of Rochester, CS Dept, Rochester, NY Lines: 44 In articlef yerazuws @CSV.RPI.EDU (Crah) writes: > The DTR down/up is due to the uVAX thinking it saw something >come from the modem (possibly a text message). VMS responds to the >characters by printing the welcome banner and Username:. >If it doesn't get a valid user/password pair in thirty seconds, >it toggles DTR to tell the modem to drop the line. > >You can get the modem/uVAX into an infinite loop this way, >(each one sending the other an error message, and getting an >error message back). PBX data switches do it easily. >This crashed our local data switch- IBX S40's can't deal with >a DTR toggle every thirty seconds. The cure was to set the >line NOMODEM on the data switch (NOT the dialup modem lines) > I was watching the modems at this installation today, and I don't think it is messages, for two reasons. All the modems are set up to be silent, i.e. not send any status messages to the vax. And, the pattern was too regular. The modem on the highest-numbered port would have its DTR ligt go off for about a second, then backk on. Within another second the next modem would have this happen, then the third modem and the final modem. About 30 seconds later the whole pattern would repeat. A few days before, whaen we hadn't managed to suppress all the messages, we would get "breakin attempt" messages on the system console when these spurious messages appeared, since VMS would assume it was someone wth a bad account/password combination. > > -Bill Yerazunis > "People at the door, Daniel. Police, Daniel" Once Dr. Manhattan finds his gluinos, we won't have these modem problems. (unintelligible to those who haven't been reading _The Watchmen_.) Mike Ciaraldi ciaraldi@rochester.edu or seismo!rochester!ciaraldi