Date: Thu, 29 Jun 2000 11:40:45 -0500 (CDT) From: Chris Dillon <cdillon@wolves.k12.mo.us> To: Shawn Barnhart <swb@grasslake.net> Cc: freebsd-hardware@FreeBSD.ORG, steinyv <steinyv@skyweb.net> Subject: Re: RJ45 Message-ID: <Pine.BSF.4.21.0006291039440.62892-100000@mail.wolves.k12.mo.us> In-Reply-To: <005801bfe18f$3f805090$0102a8c0@k6>
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On Thu, 29 Jun 2000, Shawn Barnhart wrote: > ----- Original Message ----- > From: "steinyv" <steinyv@skyweb.net> > > | I want to make my own cables. Does anyone know of a site that > describes > | the pin out of the connector, and what wires to use? I came across > one > | site, but I need to cross reference so that I could verify the correct > | information. Im trying to make a straight through on cat 5 cable. > > > [...snip...] > EIA568B Color codes (1-8): > > White Orange > Orange > White Green > Blue > White Blue > Green > White Brown > Brown This is the most common. Anyone doing any new wiring needs to use this color scheme. If you have pre-existing wiring using 568A, you need to stick with that since being consistent is more important than using the most common. If you are using either 100MBit or 1000MBit Ethernet, you MUST use one of these color schemes. Simply making up your own will not work. Each pair in the wire is twisted at a different rate to reduce crosstalk, so it DOES matter which pairs you use for what purpose. > Bandwidth-wasting trivia questions: > > What purpose does the thousands (millions?) of miles of basically > unused copper connecting pins 4, 5, 7 & 8 in CAT-5 cables > throughout the world serve? Does it provide extra mojo for the > signal? IEEE has stock options in the copper mining industry? > Overly optimistic gigabit upgrade planning? The Cat-5 standard was > the closest thing to carrying a 100Mhz signal on four wires and > the others were just part of the cabling spec unrelated to the > 100baseT ethernet spec? Because it is not Ethernet specific. You install this wiring as a part of a structured wiring system which can be used for just about any low-voltage system, including telephones, alarm systems, motor control, Token Ring, CDDI, Ethernet, etc. etc. etc... Using high-quality cable for everything is a good thing, since you never know when you might reuse a cable for something else. Those who were only doing 10MBit and installed CAT5 certified cable even though they only needed CAT3 were the smart ones, since they could later upgrade to 100MBit and now Gigabit over the same cable plant (well, sometimes... Gigabit is truly picky and your CAT5 installation has to be near perfect). > We actually have some 10m drop cables with "CAT 5" printed on the > jacketing but only four wires -- I even sacrificed one to science > and found no unused pairs in the jacket -- I've never seen any > others, and these carry 100FDX without complaints. CAT5 doesn't specify how many wires need to be inside a particular jacket. It specifies only the electrical characteristics of the cable. The most common is four-pair, but two-pair works fine for all Ethernet except for 100Base-T4 and Gigabit. -- Chris Dillon - cdillon@wolves.k12.mo.us - cdillon@inter-linc.net FreeBSD: The fastest and most stable server OS on the planet. For Intel x86 and Alpha architectures. ( http://www.freebsd.org ) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message
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