On Sat, Nov 14, 1998 at 12:59:47PM +0000, Jo Whitby wrote:
Hi all.
I hope someone can help me with this, I am trying to setup a network with 2 PC's running S.u.S.E Linux 5.2, and have various pieces of equipment, some of which I don't know their function. What I have is:
4 3Com Etherlink III 3C509BC cards - these have UTP/BNC and a 15 pin DSUB connector.
2 Ungermann-Bass, Net/One Twisted Pair Access Units, Model No. ASP310. ???
1 ASANTE FriendlyNet 10T Adapter. (UTP either end one marked "To Computer other To Network" ???
The Twisted Pair Access Units have a connector which fits the 15 pin DSUB on the 3Com cards but with only 8 pins used, these pins correspond with the printed circuit tracks on the ethernet card's connectors. The other end of the Twisted Pair Units has a single UTP connector.
My question is does anyone know the function of these Twisted Pair Access Units and the 10T Adapter? Can they be used to connect 2 computers together without having to use a hub? I also have a cable with connectors to fit the UTP sockets, it has 4 wires with both plugs wired the same.
The "Twisted Pair Access Units" are called 'Transceivers'. Way back in the dim and distant past, there were two types of ethernet cable - 10base2 and 10base5. 10base2 is the stuff that most of us are familiar with; it is often called "thin ethernet" or "cheapernet". It uses standard flexible coaxial cable, a bit like TV aerial cable (but thinner, and higher quality), and connects with BNC connector. The whole network is made up of short segments of cable, joined with a T-piece at each computer. 10base5 is also a coaxial cable, but is about 10mm in cross section, and is almost entirely inflexible (it has a bending radius of about 0.5 metres) and as such, is generally not lifted up off the floor to connect to the back of a PC. Instead, the hardware which drives signals onto the cable, and receives signals from the cable is built into a unit separate from the computer, called the 'transceiver'. This is placed on the cable, and a drop cable is connected up to the computer. The connector used for this drop cable is a 15 pin D-style connector. In 10base5, the whole network is made up of one solid piece of cable; when a tranceiver is attached, a small hole is drilled into the side of the cable to connect to the conductors. 10baseT then came along, which uses twisted pair cables. A twisted pair network is built as a tree-based hierarchy, with each computer connected directly to a 'hub'. The hubs simply repeat any signal received on any input to all outputs. All 3 forms of cabling use the same communications protocols, they just use different ways of connecting the hardware together. Going back to the story, most high-end computer systems only had one style of network connector - the 10base5 drop-cable connector, or AUI. However, this doesn't matter, as you can simply buy the correct transceiver for your network hardware - as the communications protocol is the same no matter whether you use 10base2, 5 or T, it is possible to build tranceivers for all three types. However, some PC network cards have more than one connector. In your case, you seem to have AUI, BNC and UTP connectors. This is equivalent to having BNC (10base2) and UTP (10baseT) tranceivers on the network card, and thus makes the separate tranceivers redundant. Sorry. Chuck them back in the cupboard. As for the 10T adaptor, I don't know what that is. To connect your computers you need either: a) A cross-wired UTP cable or b) Two normally-wired UTP cables and a hub or c) One length of Coax cable, two terminators and two T-pieces. The advantage of a) is that it only requires buying/building one cable, and is therefore cheap. However, it can only be used to connect two computers. If you want to connect three, you'll have to go with routes b) or c). As for b) and c), they each have their advantages. UTP networks tend to be more reliable and easier to debug, but they have a higher initial outlay as you have to buy the hub. Also, if you exceed the number of machines on the hub you buy, then you have to get another hub, and daisy-chain them. Coax networks have a lower initial outlay, and you just buy a T-piece and a length of cable for each computer you add. However, they tend to be a bit more unreliable, and are a bit of a pain to debug. Instructions to build each network: Cross-wired UTP This is the easiest. Just buy a cross-wired UTP cable (make sure it's cross-wired and not a normal UTP cable), and connect the machines together. You can make the cable yourself if you like; just do a web search for the wiring. However, the connectors are a bit tricky to put together, so unless you're confident, then just buy the cable. Hub-based UTP Get a hub, and one UTP cable for each machine. Connect each machine into one of the hub ports, and, if necessary, connect power to the hub. Coax Get a length of 10base2 cable with BNC connectors on (again, you can make this yourself if you like - you need 'RG58' cable, and 50 Ohm BNC connectors, but assembling the connectors can be a bit tricky, so if you're not confident, buy a ready-made cable). Put a T-piece on each computer, and connect one side of one T-piece to one side of the other T-piece. On the other side of each T-piece, place a 50 Ohm terminator. The network should look like: Terminator-Tpiece-cable-Tpiece-Terminator | | Computer Computer Do not be tempted to do without the terminator and/or T-pieces, it won't work if you do. Hope this helps. David Smith - To get out of this list, please send email to majordomo@suse.com with this text in its body: unsubscribe suse-linux-e