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tantivy
join:2007-03-17
Palo Alto, CA
 ·SONIC.NET
| reply to jbcg
Re: Best way to wire an old house w/out attic
Correction: 8p8c != RJ45 unless it is wired as RJ45. Ethernet != RJ45.
The RJ designations apply to a specific jack, wired in a specific wiring pattern, for a specific telephone service. There are multiple wiring patterns for the same connectors, carrying different RJ designations.
Ethernet, Token Ring, and other non-telephone applications have never had RJ designations, despite the common misuse of the RJ45 designation to describe anything using a 8p8c jack/plug.
If you call it RJ45, it had better be a keyed 8p8c, wired for a 2 wire data circuit on pins 4/5 with a programming resistor across pins 7/8 at the wall jack.
Use the correct Cat5e 8p8c jacks, and wire them to EIA/TIA-568A or B, but don't call them RJ45. | |
jbcg
join:2001-09-15
Milwaukee, WI
| I admire your insistence on use of proper terminology for 8p8c plugs. In fact, for what we're describing, "8p8c/tia568a" (or "b") would be the most accurate. (A real mouthful, huh?) That's a battle I gave up about eight years ago. It reminds me of a boss I had early in my career who insisted that everyone say "S-Q-L" instead of the more widely used pronunciation "Sequel" because IBM, who developed SQL, had not formally adopted the term. Even the IBM reps we were meeting with were amused by that--they all used the term "Sequel" as well.
Yes, "8p8c" is a technically precise description of the mechanical interface, and is used consistently in some product specs. RJ-45 or RJ45, the way it's used probably 98% of the time, is not technically accurate. Nor is a lot of terminology in our industry: "cable modem" in place of "bridge," "balun" interchangeably with "adapter," "megabyte" in place of "mebibyte" (a word most people don't even know), and the use of the words "upload" and "download" almost interchangeably. Then there's "Band Aid" versus "adhesive strip bandage," "Sawzall" versus "reciprocating saw," "Koolaid" versus "artificially fruit-flavored beverage," and on and on.
All of those distinctions are appropriate in technical documents, specifications, orders, legal briefs and legislation. A good technologist should kept them in mind. But when pointing someone who isn't necessarily a technologist to a body of useful information that uses vernacular rather than technically precise terminology, it's more considerate to use the term that is most broadly used to discuss the technology.
For example, try googling "How to wire 8p8c" to get info on how to terminate an Ethernet cable. Then try googling "How to wire RJ-45". Big difference, huh?
You'll notice, too, that most equipment and software manufacturers including Microsoft, Intel, Broadcom, Netgear and Cisco use "RJ-45" or "RJ45" in their printed data sheets and other documentation.
Going along with vernacular usage, especially where the usage is so unlikely to cause problems in implementation, also helps avoid a lot of eye rolling (and wasted time) in meetings.
But thanks for the correction--I know it warms the hearts of a lot of us who like to hear things stated precisely!
Joey | |
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