warren@pluto.UUCP (03/31/87)
I have used Ethernetted machines before, but never had to connect the things. I find myself with a Pyramid and a Xerox workstation, both of which run Ethernet and the usual services, both with DB15's on the back labeled ethernet. What is it that I have to buy to hook these to each other, (tranceivers?, cable?) and where do I get it? thanks -- warren /|/~\~~\ Why doesn't life come with subtitles? |__/__/_/ | seismo!philabs!tg!pluto!warren /
hedrick@topaz.UUCP (04/03/87)
If your machines are in the same room, I recommend using a multiport transceiver, i.e. not having an Ethernet cable at all. A multiport transceiver is normally used to connect 8 machines to Ethernet using a single transceiver. I.e. on one side you connect 8 transceiver cables to 8 computers, and on the other side you connect one transceiver cable, to the real transceiver. It can be thought of as an "octopus plug" for Ethernet. However if you have <= 8 machines, there is no need for the transceiver at all. So you only need 3 things: the multiplexer, and two transceiver cables - one for each machine. Depending upon the type of multiplexer you may also need a turnaround plug to put in place of the wire that would normally put to the transceiver, but some of them just have a switch to flip to say no transceiver. Many companies make these, including TCL, Cabletron, Interlan, DEC, and Intel. We have many of the TCL ones, and have never had any problems with them. We are now testing a Cabletron one. It is smaller, and has some cute LED's, to let you see what is happening on your network. Other parts of the University have used Interlan, DEC, and Intel without problems, though the DEC one makes our HP Lanalyzer think there are lots of collisions. Also, TCL has *very* slow delivery. I'd make an unambiguous recommendation for Cabletron, except that we haven't actually tried it yet with a Pyramid or Xerox workstations, whereas we have tried the TCL that way and so are sure it can work. But I'd be shocked if the Cabletron didn't. DEC's does some odd things that make our HP Lanalyser think there are lots of collisions on the net. I don't know about Intel's. When ordering this (or a real transceiver) you will need to know which of the 3 standards your machines supports: Ethernet version 1, Ethernet verison 2, or IEEE 802.3. Most newer machines are built to handle either Ethernet 2 or IEEE 802.3. In general, you should check with your vendors to see which they support. Unfortunately, salesmen generally think that Ethernet and IEEE 802.3 are the same, so you may get wrong results unless you find the one person in the company who knows what is going on. There are different versions of transceiver cable, and different transceivers for each standard. Many newer transceivers can handle all 3, using switches to configure them. TCL Multiports have plugin modules, and they have all 3 kinds. The Cabletron can be configured for any of the standards. We use Ethernet version 2 throughout our installation, except for a couple of machines that absolutely have to have version 1. Apparently the IEEE standard does make some improvements, so some people use it where they can. I would think both Pyramid and Xerox would support it, but what we actually use here is Ethernet 2, so I can only verify personally that they work with Ethernet version 2. Note that a multiport transceiver is probably not completely cost-effective for 2 machines. It is probably more expensive than 2 transceivers plug a few feet of coax. However it isn't terribly expensive, and is better in the long run. You don't want to tap your cable any more than you have to. Transceivers have to be right next to the tap. It's inconvenient to plug cables into them, and doing a lot of connecting and disconnecting can disturb the connection. We like to be able to plug and unplug things for testing. We also like to have a few spare outlets to plug in network analysis equipment. So we hide the actual taps and transceivers somewhere where we will never have to touch them again, and make the actual connections to the multiport boxes. Anyway, I suggest contacting one of the vendors on the list above and asking them to make sure you aren't missing any parts. I think a multiport plus 2 transceiver cables is all you need, but there might be some other widget I am forgetting. Certainly Cabletron can supply all the cables, etc, and I think the others can as well.