tex@shrubbery.NET (Austin Schutz) writes:

Get two modems.

POTS ---- Modem 0 ---- Modem 1 | | UPS AC Utility AC

This only really makes sense if you have your terminal server w/ redundant power, one utility AC and the other UPS AC.

I've had troubles with two auto-answer modems daisy chained off the same pots line, but a good solution for some cases. A few people asked how I currently solved the problem. I'm using three different methods depending on the importance of the facility. 1) Nothing, and praying the modem answers Obvious problems - You name them 2) A Digital POWERswitch, which is a cool box containing essentially an automatic transfer switch with two AC power cords for a piece of equipment with one AC power cord (e.g. modem, switch, hub, etc) Obvious problems - Trying to find a Compaq salesperson who will let you order one - A big bundle of wire stuffed into the corner of the rack - People get confused, and unplug the equipment from the POWERswitch, and plug it directly into the wall outlet. I don't know why, but for some reason people look at it and think "That can't be right," and zap, there goes my modem. 3) "Network monitoring systems," which is a self-built Alpha unix box, with internal 14.4 modem (I've found them more reliable, under more conditions than 28.8 or 33.6. I don't need speed, I need a connection.), 8 serial ports to connect to the equipment consoles, and DC power supplies connected to the dual A&B battery supply. Unlike AC power cords which people unplug at will, DC power scares enough people so they don't touch it. Obvious problems - Not labeled by UL, FCC, or NEBS; some building engineers object to anything without approved labels - DC powered, Ok for telco, but a problem other places - Vendor field maintenance not available, self-built - More complicated systems fail more often None are perfect, and each can fail in different interesting ways. Now, back to your regular network operations discussions. -- Sean Donelan, Data Research Associates, Inc, St. Louis, MO Affiliation given for identification not representation