cball@ishmael (11/15/88)
There was an outfit called TCL demonstrating twisted-pair ethernet on the InterOP88 floor show. Unlike Synoptics, whose implementation requires a repeater to connect it to a coax network, TCL's implementation is basically a multiport transciever with twisted-pair out to a "transciever" that reformats signals from twisted-pair to normal drop cables. The advantage is that TCL's implementation connects to normal coax with a transciever instead of two transcievers and a repeater. In short, TCL appears to have a product that is both less expensive and more flexible. The problem is that other than the aforementioned trade show, I've never heard of TCL. Is there anyone out there who has experience with TCL equipment or better yet with their twisted-pair ethernet products? Thanks for any info, Charles Ball cball@inmet.inmet.com Intermetrics, Inc. uunet!inmet!cball
kwe@bu-cs.BU.EDU (kwe@bu-it.bu.edu (Kent W. England)) (11/17/88)
In article <123500001@ishmael> cball@ishmael writes: > >There was an outfit called TCL demonstrating twisted-pair ethernet on >the InterOP88 floor show. Unlike Synoptics, whose implementation requires >a repeater to connect it to a coax network, TCL's implementation is >basically a multiport transciever with twisted-pair out to a "transciever" >that reformats signals from twisted-pair to normal drop cables. >The advantage is that TCL's implementation connects to normal coax with >a transciever instead of two transcievers and a repeater. In short, TCL >appears to have a product that is both less expensive and more flexible. Sounds like you are asking how to connect to a "backbone" network. Most of the vendors working on Ethernet concentrators are allowing for a "back-end" connection to a backbone or trunk Ethernet independently of the "front-end" twisted pair transceiver connection. There isn't really any difference between the "back-end" and the "front-end" except to allow for the kind of media flexibility you want and, for the future, to be able to plug in bridge functionality instead of simple repeating. All these TP concentrators use multiport repeater technology, not multiport transceiver technology. I suggest you look at: Cabletron MMAC Ungermann-Bass Access/One Hewlett-Packard TCL David Systems Wang and there must be others I've overlooked here that were involved in the 10BaseT standard effort. You will find that most of these vendors have options for the type of "backbone" Ethernet that the concentrator can attach to. >The problem is that other than the aforementioned trade show, I've never >heard of TCL. > TCL isn't as well known as it might be. TCL came out of PARC where TCL principals built the first transceivers for Ethernet.
chris@spock (Chris Ott) (11/17/88)
Sure, I've heard of TCL. Silicon Graphics ships TCL Ethernet
transceivers with their IRISes. We also bought a multiport transceiver
from them. After a year and a half, we've never had any problem with
either of them. The single TCL trancseivers aren't as pretty as the 3 Com
transceivers, but they sure are a heck of a lot easier to install.
The multiport transceivers are great. You take a single transceiver,
attach it to the Ethernet coax, and plug the drop cable into a port on
the multiport box. Then you can plug eight computers into the box without
making another tap onto the coax. Better yet, when all eight ports are
full, and you need to add another machine, there's still no need to make
another tap onto the cable; just buy another multiport box. You can take
an output from the first multiport box and plug it into the input of the
second, effectively giving you seven more connections without another
tap on the coax. As far as I know, this goes to infinity.
They have a big advantage over the DELNI multiports is that, when
DELNIs go bad, you have to send back the whole box. With the TCL multiports,
each port is on its own seperate board, so you just have to send back the
port that went bad. They are also cheaper to replace that way. You can even
get a box with less than eight ports in it, if you don't have the money
to spend on a full box.
I have no association with TCL other than being a very satisfied
customer.
--Chris
-------------------------------------------------------------------------------
Chris Ott
Computational Fluid Mechanics Lab Just say "Whoa!!" and
University of Arizona vote for Randee!!
Internet: chris@spock.ame.arizona.edu
UUCP: {allegra,cmcl2,hao!noao}!arizona!amethyst!spock!chris
-------------------------------------------------------------------------------markf@censor.UUCP (54328745) (11/18/88)
In addition to the other companies listed as having direct coax connections for their twisted pair implementations, SynOptics now has a concentrator that contains a single AUI port to connect to a coax transceiver. The Model 2530 Workgroup Concentrator contains 8 twisted pair ports (RJ-45 connectors) and the AUI port. It implements the repeater function as well. It can be integrated into the rest of the SynOptics star-wired architecture. sh: q: not found
root@sbcs.sunysb.edu (root) (11/18/88)
We've used TCL equipment for a few years now. We have several of their multiport transceivers. We have not had any fail. Recently we switched over to Inmac gear - it tends to have a bit more in the way of status indicators. Nice for debugging problems ever now and then. Rick Spanbauer SUNY/Stony Brook
wallace@cme-durer.ARPA (Evan Wallace) (11/18/88)
In article <853@amethyst.ma.arizona.edu>, chris@spock (Chris Ott) writes: > ... You can take > an output from the first multiport box and plug it into the input of the > second, effectively giving you seven more connections without another > tap on the coax. As far as I know, this goes to infinity. > Remember however that the total length of a drop (AUI) cable cannot exceed 50 meters. That means from any machine to the trunk cable. Check with TCL on a limit on the number of boxes that can be daisy chained, I have heard conflicting reports on this. I agree with the general tone of the quoted message. Our TCL multiport tranceivers have proved reliable and flexible during the four years we have used them. Advantages of the multiport concept have been: ease of isolation for debugging purposes ease of installation (fewer taps) increase in effective cable length (none wasted adding multiple taps for a single room) ease of reconfiguration (move box from net to net easily) improved overall reliability (taps have been the least reliable part of are E'net installations) Disadvantages: ? Evan K. Wallace at the National Institute of Standards and Technology (formerly the NBS) wallace@cme.nbs.gov uunet!cme-durer!wallace
eshop@saturn.ucsc.edu (Jim Warner) (11/20/88)
In article <735@morticia.cme-durer.ARPA> wallace@cme-durer.ARPA (Evan Wallace) writes: >In article <853@amethyst.ma.arizona.edu>, chris@spock (Chris Ott) writes: > >Disadvantages: > ? I have no complaints with the electrical properties of TCL transceivers. They work fine. I don't, however, like their vampire tap. The problem I see is it has exposed metal that is electrically connected to the outer shield of the yellow cable. It is too easy for a transceiver in a cable tray or under a raised floor to be inadvertantly moved so that the metal clamp makes contact to building steel. Instant ground loop. An Ethernet segment must be grounded in one and only one place. If you're going to use their transceivers, take pains to be sure that the exposed clamp can't come in contact with ground. I'd rather not be that careful -- so I haven't been buying their transceivers. jim warner U.C. Santa Cruz