Re: Common operational misconceptions
"Ethernet/Token Ring/Cisco Console/whatever uses an RJ45 connector" RJ45 defines a keyed 8P8C type connector, wired in a specific manner, for a specific 2 wire telco service. Incompatible with the above on several levels. "RJxx" == specific connector/wiring pattern for specific telco applications. Non-telco uses need not apply. One of these days I'm going to start carrying around some actual RJ45 type cables to hand out to those who ask. "DB9" DB defines a D series subminiature connector with a size "B" (nominal 25 pin) shell. DE defines a size "E" (nominal 9 pin) shell. DA15, DB25, DC37, DD50, DE9, etc.. Also DB13W3 (old Sun monitors), etc. If in doubt, refer to ITT/Cannon catalogs. (my oldest is from 1971). -- -- Welcome My Son, Welcome To The Machine -- Bob Vaughan | techie@{w6yx|tantivy}.stanford.edu | techie@tantivy.net AF6RR | P.O. Box 19792, Stanford, Ca 94309 | 1-650-469-3850 -- I am Me, I am only Me, And no one else is Me, What could be simpler? --
On Sat, Feb 18, 2012 at 1:19 AM, Bob Vaughan <techie@w6yx.stanford.edu> wrote:
"Ethernet/Token Ring/Cisco Console/whatever uses an RJ45 connector" RJ45 defines a keyed 8P8C type connector, wired in a specific manner, for a specific 2 wire telco service. Incompatible with the above on several levels. "RJxx" == specific connector/wiring pattern for specific telco applications. Non-telco uses need not apply.
RJ45 is really an example of what was originally a misconception became so widespread, so universal, that reality has actually shifted so the misconception became reality. When was the last time you ever heard anyone say "8P8C connector?" Joe public caught on to "RJ45", so now that word means something different in common usage than what it was specified to be. When was the last time you heard someone say 8P8C connector in reference to Ethernet? Nowadays it is technically ambiguous to say "RJ45"; are you talking about [a] The original standard, Registered Jack 45, which was a specific connector together with a specific pinout (which is not Ethernet over UTP)? Usage of the connector is exceedingly rare, and will hardly ever be referred to. Or [b] "Ethernet" connector; The generic 8P8C connector (which has a certain resemblance to RJ 45) is specified for use with TIA/EIA 568 compliant cable termination ? Now instead of [a] being correct and [b] being always the misconception..... [b] is "correct" in common usage. And you have to decide based on context of the conversation which defintion of RJ45 is intended, but [b] will almost always be the correct definition. -- -JH
On Monday, February 20, 2012 09:07:20 PM Jimmy Hess wrote:
RJ45 is really an example of what was originally a misconception became so widespread, so universal, that reality has actually shifted so the misconception became reality. When was the last time you ever heard anyone say "8P8C connector?"
And then there's the 10C variant used on some serial port interfaces (like those from Equinox)..... '8 pin modular plug' is reasonable, though, and is what I'll typically say, with the modifier 'for stranded' or 'for solid' conductors, as it does make a difference. I haven't said 'RJ45 plug' in years. Yeah, it's a bummer that the keyed RJ45 plug got genericized to the unkeyed variant; at least the unkeyed plug used for TIA568A/B will work in a true RJ45 jack.....
Lamar Owen <lowen@pari.edu> wrote:
On Monday, February 20, 2012 09:07:20 PM Jimmy Hess wrote:
RJ45 is really an example of what was originally a misconception became so widespread, so universal, that reality has actually shifted so the misconception became reality. When was the last time you ever heard anyone say "8P8C connector?"
And then there's the 10C variant used on some serial port interfaces (like those from Equinox).....
At least "RJ45-X" is still unambiguus. <wry grin>
----- Original Message -----
From: "Jimmy Hess" <mysidia@gmail.com>
RJ45 is really an example of what was originally a misconception became so widespread, so universal, that reality has actually shifted so the misconception became reality. When was the last time you ever heard anyone say "8P8C connector?"
Joe public caught on to "RJ45", so now that word means something different in common usage than what it was specified to be. When was the last time you heard someone say 8P8C connector in reference to Ethernet?
WADR: horseshit. I, in fact, just wrote a cabling RFQ yesterday for a new building, and *I* write "8P8C male modular connector". So, in short: if you *actually need to be saying it*, you actually need to be saying it correctly, because you're talking to people who know the difference. They won't say anything, mind you, and you'll get what you want; they'll just think you're a clueless dilettante. Cheers, -- jr 'yes, I'm a prescriptivist[1]' a [1] The *point* of language is communication; this is impossible if words "mean what people want them to mean, no more, no less". -- Jay R. Ashworth Baylink jra@baylink.com Designer The Things I Think RFC 2100 Ashworth & Associates http://baylink.pitas.com 2000 Land Rover DII St Petersburg FL USA http://photo.imageinc.us +1 727 647 1274
participants (5)
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Bob Vaughan -
Jay Ashworth -
Jimmy Hess -
Lamar Owen -
Robert Bonomi