jerry@olivey.olivetti.com (Jerry Aguirre) (10/22/88)
In article <337@ivucsb.UUCP> steve@ivucsb.UUCP (Steve Lemke <steve>) writes: >Actually, another alternative for a situation where there are lots of modems >is to replace them with a rack of modems. I've seen a rack unit for VenTel >modems, and also for USR Courier 9600s - when you want to add more modems, >you just slide more cards in - power is all taken care of with one plug! >However, I guess many people have different kinds of modems that aren't easily >written off and replaced - also, I'm not sure if the Telebits are rack- >mountable or not. But, if acceptable, this is a much nicer way to do things... I have the brochure for Telebit sitting in front of me. They have a PC card version and a rack mount version in addition to the stand alone. It is tempting. The rack eliminates a big mess of cabling. There are disadvantages though. A minor one is cost. You have to need more than a few modems for the rack to pay for it self. (Of course if you only have a few then you don't have a mess of cabling.) But, if you are adding modems gradually, a few at a time, it is hard to justify the rack. Second is reliability. You see you have all these modems dependant on the rack for power. And power supplies do fail, even the best designed ones. Of course you can justify a spare power supply if you have enough modems. The problem is that it takes all the modems down at the same time. Right now if one of my modems fails UUCP is smart enough to try another and things keep on working, even at 3AM Sunday morning. I do have some older Racal-Vadic modem racks. They have an option for a redundant power supply. When one of the supplies fails a little light starts blinking but all the modems continue to work. When I eventually notice this, I can pull that supply and insert a new one. All without a single second of down time for any of the modems. I don't know if Telebit offers such an option for their rack. And, finally, there is the loss of flexability. Later on, when I upgrade to Trailblazer mark 900000 modems, use ISDN, or whatever, I am stuck with a rack full of cards. With the standalone units I can give them to people to take home, ship one to another site, or whatever. Maybe if the card that went in the rack was the same as the one in the stand alone (a rack mount for one card?). But even then you wind up having to justify the cost of buying the standalone boxes to house cards that have become obsolete. For me this is the big problem. The technology changes too fast to commit to a dedicated solution. Of course for someone with lots of modems the tradeoffs would be different. Jerry Aguirre