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Author Topic: Ethernet patch cables  (Read 7943 times)

Bob Leonard

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Re: Ethernet patch cables
« Reply #10 on: July 02, 2011, 01:24:19 AM »

right. i said if you dont wire to the standard(s) it could result in a split pair. Depending on how you do it, it may not result in a split pair. I have come across alot of cables made by people who shouldnt have that for example go BL|W/BL|OR|W/OR|GN|W/GN|BN|W/BN that example gets you a split pair as one signal is split across OR and W/GN

 
The type cable you call out here is actually a standard used by any number of phone providers and is used from the jack to the handset. In the world of ethernet under 10gb only the orange and green pair are used, as the blue and brown pair are reserved for phone according to the WECO/ATT standard, sometimes referred to as T568A/B.

ethernet doesnt use the WECO/ATT standards, ethernet uses TIA/EIA standard. The old western electric 8P8C wiring standard 'WECO' was replicated as 568B. Blue and Brown are used for power over ethernet in 10/100 PoE environments.

well I suppose I'll agree to disagree, however I'll say that after more than 30 years of installing and designing large scale cable plants, network infrastructures and installing / designing world class wide area networks that you may be right and wrong but not know.
 
The TIA/EIA-568-B standards were first published in 2001, and replace the TIA/EIA-568-A standards set released in 1991, which are, as is WECO, now obsolete. Prior to that time and first introduced in the early 70's was the WECO, Western electric standard, 568B, and this is the standard used all through the late 70s and into the present day. ALL of the TIA standards in use today are the result of the WECO standards being further defined.
 
The WECO standard explains the color code for an RJ-45 connector and cable plant specs, "B" used for ethernet, and "A" actually the standard used by IBM almost exclusivly, but not even close to todays "A" spec defined by TIA. The TIA standard is a result of faster transmission rates and the need for the industry to define infrastructure cabling best practices in a world where everything needs a connection using the house cable plant. The TIA code is due to the efforts of 12 companies, the one I work for included.
 
568B will certainly support 1000mb transmission over standard CAT5 cable and two pairs. HP and UNISYS both have adapters that will do just that, and there are more
 
Your are correct in stating PoE is the TIA designated use for the blue and brown pair, which WECO first designated for use with telephone systems, and which were mostly powered using 78V or more. I can also assure you that a number of manufacturers offered ethernet cards which had a backplane on the back supporting the RJ-45 and an RJ-11 which did nothing more than split out those pairs enabling you to plug your phone into the back of the card vs a seperate jack on the wall or floor.
 
This included HP who brought a small number of engineers to Maryland in 1989 to work with and suggest design improvments to their soon to be released product(s). A card of this type was one of th products and I was one of the engineers. The TIA standard is nothing more than further definition of "reserved for phone use". 
 
You are correct, the TIA standard IS todays standard, but to the majority of us old timers in the industry 568B is the dominent standard, and we don't really care what you put in front of that. You can splice, dice, and disect the code, but in the end it's all based on WECO, ATT, a 66 block, and a punch down tool. See you on the flip side.  ;)
 
 
 
« Last Edit: July 02, 2011, 01:26:55 AM by Bob Leonard »
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Re: Ethernet patch cables
« Reply #10 on: July 02, 2011, 01:24:19 AM »


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