On Sun, 07 Mar 2004 11:08, you wrote: <snip> > > >>>The point of the story is that it might be worth your while putting > > >>> an old 10MHz card in one of the machines to force your net to run > > >>> at 10MHz. If it works at the lower frequency, then that more or > > >>> less proves that you have problems with noise on the cable run.
or it could be a poorly crimped connector, which may allow certain frequencies through due to capacitive coupling. > > >>What can cause noise on network cables? > > > > > >Cross-talk from the mains would be the most usual. In any situation > > > remotely 'industrial' the mains wiring can be a real noise generator. > > > > > >As a previous poster stated running Ethernet close to mains wiring is > > > usually the problem. imho, At least 50 cms in practice leave at least > > > one stud space between them in a wall. Err, 50mm (5cm) is the accepted norm, same as telephone cables (www.telepermit.co.nz/Ptc103.html) > > What about patch leads and power leads of computers running close > > together? > > Bundled up together in a nice neat cable run would not be a good idea. > It's running the Ethernet and mains wires parallel for any distance that > causes the problems. A few cms, like through the the cable feed hole in a > desk is ok, but tying the wires together for metres is death for the > Ethernet signal. Telecom also point out (for telephone wires) that if you are relying solely on the 50mm physical separation from mains wiring not to let this run for more than 3m. I have to say that premises wiring is *not hard*. You have 8 wires, all uniquely colour coded. You have 8 points to connect. You either do or do not make a good electrical connection in the right place. I have wired this house with 12 cat 5e sockets (and I will do another 12 I think). I bought 2x50m rolls of solid core cat 5e cable, 12 wall sockets (and assorted wall plates) and a 12-way patch panel. I also bought a punch-down tool so I could properly terminate the wires. There are two wiring standards, 568-A and 568-B. Electrically they are identical, but they differ in that the green and orange pairs are swapped. I used the 568-A colour code for the house wiring. Obviously (!) you have to wire each end of the premises cable to the same standard, and most connectors have a colour coded sticker next to the connection points so you can't make a mistake (* see later). For patch cables the choice of standard does not matter since they are electrically the same. My patch panel is in the hot water cupboard, sorry, the "Comm's Cupboard", which is centrally located in the house. You don't need a patch panel, and you can just terminate the free ends in the, ah, "Comm's Cupboard" as Yuri has done, however you must have the right RJ45 free plugs for solid cable. The way to tell if the cable is solid or stranded is to strip a little bit of insulation off the core. Inside is either one solid copper wire, or several very thin strands of copper wire. Stranded cable is very flexible and used for patch leads. Solid cable is the correct cable to use in walls and under the house for permanent wiring. The RJ45 free plugs should be clearly identified as suitable for solid or stranded cable. If they are not so identified I'd suspect they are for stranded cable as that is the most general application. So, I pulled 12 pieces of wire under the house and popped them up into new electrical back boxes in various rooms. I punched them down on the patch panel to 568-A standard, and then punched down the individual sockets to 568-A standard before snapping them into the wall plates and screwing them to the back boxes. I then ran a long (20m) ethernet patch lead from each socket, one at a time, to the hallway near the patch panel and a short ethernet patch lead to the corresponding socket on the panel. This way I could use a multimeter set to test continuity and shorts from pin 1-1 2-2 etc. from the panel to the room socket. Crude but effective. I had one error (* see earlier) where the colour code sticker on one of the room sockets had been stuck on upside down and I didn't notice and just followed the colour code... always leave 20 or 30cm of slack to allow the connections to be remade if there is a problem. Yuri, your message of success has just arrived, but I am going to post this anyway, as you have demonstrated that, as usual, the simplest explanation is the correct one. Andy
