OK. Soapbox rant time (with apologies to Ed).
Once upon a time (back in the '80s) there was no standard for Data cabling. To quote the Bible when they talk about evil times: "Every man did what was right in his own eyes."
We had Ethernet (Thick and thin coax), we had Starlan, we had IBM type I, II & III, we had twinax, we had dual coax, we had asynchronous networking over serial cables and modem eliminators, we had.....everything!
For cabling installers it was heaven!
Somene would move into a new office and we would rip out what was there and install new wiring. A firm would hire a new DP (Data Processing) chief and we would rip out everything and put in his favorite flavor. It was wonderful!
In the mid-to-late '80s the EIA (Electronics Industry Association) and the TIA (Telecommunications Industry Association) got together with cabling and equipment manufacturers and decided to create standards for all aspects of networking. One of the first standards they created was the wiring standard. It was the 568 (no letter) standard. It was equivalent to todays "A" wiring.
Then AT&T popped up and bitched. They had a very similar wiring standard that they used in their Dimension series PBXs. They had thousands of people trained in it and....they were AT&T.
To make a long rant somewhat shorter they insisted that if the industry did not adopt THEIR standard, then they would not participate. Well no one wanted the '800 lb. gorilla' to be on the outside of the tent pissing in, so they brought them in to the tent by agreeing that there could be two standards - "A" or the original standard and "B", the alternate standard that followed the AT&T wiring plan.
When I teach the IBEW apprentices about Data wiring and termination I tell them that when they show up on the job, the first question they have to ask is "A or B?". If their foreman looks at them blankly they should prepare for a disaster and the prospect of much overtime.
And as far as the disaster everyone in the industry foresaw (We'll never wire another office again! Who would ever need anything more then 100mbs Cat5?). Hah! Cat5E, Cat 6, Cat 6A and coming soon - Cat7!
I now return the soapbox to Ed.
Sam
