586 B verus a straight thru cable

[1Drisnil]

Can someone explain why a straight thru cable will work as a patch cable is the data jacks and wall cable drop were crated using 586B format?

Also, if this is true that you can use a straight through cable for certain speeds (Cat 3) why would one not actually use straight though cable and insist on using the proper wiring for a patch cable?

I got into a discussion with a co-worker and could not convience him to use standard code wiring for networking purposes. Now I would like the understand what is lacking in my understanding for future discussions.

All help (with flack) is appreciated. =)

"...understanding "The Why" is half the battle!" - Anonymous.

 

[daronwilson]

You might search this forum, I think we've beaten this to death a few dozen times. In a nutshell....

Ethernet transmits and receives on 'pairs' of wires, transmitting on one pair and receiving on another. The 'pair' is twisted together to keep the signal on that pair of wires and keep it off the other wires adjacent to it.

In the 10 mbs days, it was very forgiving, one could get away with flat satin cables as patch cords with no 'pairing'. The standard was rather robust and the wire not very critical. You could run 10mbs on barbed wire almost.

At 100 mbs, the system is not so forgiving. The use of Cat5, 5e and 6 provided the necessary isolation between the transmit and receive pairs to increase the data throughput. Flat satin cable with no pairing might actually make a connection on short patch cables, miswired patch cables might actually get you connected for short lengths as well. However, when you go above a certain distance (30-50 feet or so?) generally the link just won't run unless you have the plugs wired correctly with the 'pairs' of twisted cable. Too much crosstalk between wires.

At 1000 mbs, all four pairs are needed and they must be paired to make the thing fly. In this mode, we are effectively doing 250 mbs on each pair of wire. Not much room for error, and really no spot for anything other than the correct wiring scheme.

Just FYI, a 'straight through data cable' is one that is wired pin 1 to pin 1, pin 2 to pin 2, etc. BUT is wired with the proper pairs so that 1 and 2 are a pair; and 3 and 6 are a pair. It almost sounds like you are referring to a straight through cable as one that is flat satin.

For data use, a 568B wired cable is a straight cable. The only other kind you would encounter is a crossover cable in which the pairs are reversed on one end (wired 568A on one end, 568B on the other end for 10/100 use).

For telephone use, most modular cords are not straight, we refer to them as rolled. This is the method used for most telephone installations, no pair swapping, just one plug is flipped over on one end.

Hope that helps.

It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com

 

[Servamatic]

Personally, I wish the term straight thru would dissapear.
It's sort of a misnomer. At least it leads to confusion.
Daron explained the why's I just wanted to add my .02 worth.

We have Telco cords which are a rolled configuration, meaning they reverse polarity from one end to the other.
We have Data patch cords which go pin to pin in numerical order without the roll, this is why they were originally called straight thru.
You also have cross-over cables which Daron explained.

If we stick with Data or Telco patch cords it would eliminate some of the confusion...HOPEFULLY...


Richard S. Anderson, RCDD

http://www.servamatic.net

 

[jimbopalmer]

had the folks designing 10BaseT used pins 1 & 2 and 7 &8 we would all have less grey hair, but we get to life with reality

I tried to remain child-like, all I acheived was childish.

 

[1Drisnil]

Thanxs for all the answers. Very educational to say the least.

BTW, what does RCDD standard for?

"...understanding "The Why" is half the battle!" - Anonymous.

 

[daronwilson]

Registered Communications Distribution Designer. With this title and $4, I can get a good coffee at Starbucks

Check out

http://www.bicsi.org

for further information on the program.

Good Luck!

It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com

 

[Servamatic]

Really Cool Data Dude.....

Richard S. Anderson, RCDD

http://www.servamatic.net

 

[Servamatic]

With the title and 3.00 at Tully's I can get a GREAT cup of coffee....

Richard S. Anderson, RCDD

http://www.servamatic.net