MOLTA@UNTVAX.BITNET (02/07/90)
Life is not so great when you're trying to sell people on the merits of twisted-pair Ethernet. I think I've convinced people that from a management and reliability standpoint, a star topology is infinitely superior to a bus topology even though it is a little more costly up front. People are particularly enthusiastic about the concept of plugging their computer into the wall the same way they plug their phone into the wall. Now for the sticky part that I need some input on. The group that is responsible for maintenance on campus is having reservations about the use of twisted pair cabling. Specifically, they are concerned about potential problems with induced non-linear effects on the cabling system. I'm not an engineer, but I think the major fear relates to the possibility that a severe lightning storm (we have more than our share) might result in high current levels being introduced into the twisted pair wiring plant, thus resulting in damage to cards and concentrators. Keep in mind that we are not talking about direct lightning hits and we are not planning to run twisted pair between buildings. Their concerns relate only to induced effects. My position has been that I have never heard of a serious problem with twisted-pair Ethernet that was caused by induced current. I suspect that if major problems did exist out there that I would have seen reports in the trade press that this was a major concern. Furthermore, I would think that such problems would occur in ISDN networks as well and it seems that AT&T and others are investing a whole lot of resources in this technology. Has anyone on the list experienced any problems of this sort? Are there standard precautionary measures that should be taken to avoid such a disaster? Any input would be greatly appreciated. Dave Molta University of North Texas
ronc@XLNVAX.EXCELAN.COM (Ron Cully) (02/07/90)
Although I haven't looked through any specs, I would hope
that vendors protect their equipment from such things. But
then again, a very reliable EE type who has designed several
communications controllers said that most that he's seen
only protect for accidental installation to a 48V phone
circuit. I would check out the specific vendors directly
and see if they might have some solutions.
Another interesting problem I've heard of as a bigger problem
is making sure that your wiring closet protects your data
circuits from Mr. Telco Repairman. I've heard of more than
one case where phone circuits were connected to a data line,
or a data line was disonnected when moving phone extensions
etc... I guess that some guys think that all punch-down blocks
are phone lines.
Good luck!
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Ron Cully Voice: (408) 473-8363
E-mail: ronc@novell.com FAX: (408) 433-0775
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The views expressed are my own and do not necessarily reflect
any official views of Novell.CUTRY@STLAWU.BITNET (Domenic D. Cutry) (02/07/90)
Dave, We are (in my humble opinion) the very center of the lightning capital of Northern New York. Our campus sits on a knoll overlooking a valley surrounded by the adirondack mountains. If there's an electrical storm within 100 miles we get hammered. We survived several storm's during the installation process of our almost brand new campus wide fiber/UTP network. Our system covers 60+ on a couple of square miles. Although we haven't been running long enough to endure one full thunderstorm season, I'm very confident that our problems will be minimal.