On Wed, Mar 27, 2002 at 01:56:27PM -0300, Henrique de Moraes Holschuh wrote: > For 10BaseT and 100BaseTX networks, the correct wiring is: > > 12356478 12356478 (straight, aka NIC<->HUB), where 12 is the first > pair, 34 the second pair, etc. DO NOTICE THE SPLIT IN THE SECOND PAIR! > > Crossover is: 12356478 34156278 (NIC<->NIC) > > Only the first+second and third+sixth positions are used in 10BaseT and > 100BaseTX. You wire it 12345678 12345678 and you will be inducing a lot of > noise in both the ethernet wiring, and anything else next to it. If you > have been doing such a stupid thing around your home or office, redo it > right. > > And please respect the minimum and maximum lengths for the cabling, or you > will have problems. An addendum: since cat5 cable can't be ribbon cable, I find it confusing to refer to the wires by numbers. When I explain this I use the colors instead. So, a straight-through cable is orange-white, orange, green-white, blue, blue-white, green, brown-white, brown. Use this scheme at both ends. A crossover cable has one end as above, and the other end is green-white, green, orange-white, blue, blue-white, orange, brown-white, brown. What you said, a different way :) More useless info: I believe the middle 4 pins are wired that way to allow cat5 cable to be used as phone patch cords (the middle pair is line 1, the outer pair is line 2). Also, I've seen crossover cables that omitted the blue and brown pairs completely (that is to say, they weren't crimped into the plug). If you find yourself making cables regularly, get a tester that tests continuity and attenuation - they're a lifesaver. Nothing sucks more than troubleshooting the tough network problem that's caused by an intermittent in your homemade cable. -- Nathan Norman - Micromuse Ltd. mailto:nnorman@micromuse.com Gil-galad was an Elven-king. | The Fellowship Of him the harpers sadly sing: | of the last whose realm was fair and free | the Ring between the Mountains and the Sea. | J.R.R. Tolkien
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