New Data Center Standard

mstansberry writes to tell us that the Telecommunications Industry Association (the people who brought you the CAT standards for unshielded twisted pair cabling) recently published a 148 page document meant to standardize the design considerations for every single aspect of a data center. The standard covers everything from site selection to rack mounting methods.

Comments

Re:twisting

[Mr. Flibble]

because of the extra twisting there is less crosstalk. The less crosstalk, the more information you can pump down the wire, thus the difference between Cat 3,5 and 6.

(FYI, crosstalk is interference from a parralell channel in the wire)

Re:twisting

[rusty0101]

Not sure entirely myself, however as a thought, having a constant twist (different from one pair to the next, but the same for the length of the cable) could set up a situation where two cables are in phase at several points alog the cable run, and some signal transfer may hapen.

Varying the twist rate along the run of a pair, as well as doing what you can to keep it out of phase with other pairs by braiding, or other means would make it possible to set up a longer cable run without viable phase transfer points that could cause signal bleed between pairs.

However that's just conjecture on my part. I am sure someone will come along who can give us the math to show that my conjecture is entirely wrong.

-Rusty

Re:twisting

[SoloFlyer2]

Varying the twist rate only helps when u have several cables together ( Think 4 or 5 cables in a conduit ). Basically it just reduces the chance that 2 cables next to each other are going to have exactly the same twist rate.

In other words it reduces cross-talk between cables :)

Re:twisting

[DaEMoN128]

I am BICC certified. There is a difference between CAT3 and CAT 5. The twists are much more pronounced on CAT 5. It may not look like it, but there is a big differnece. There is also different amounts of twists per pair. CAT 6 is something I havent had much hands on with (we use mostly fiber for that stuff). CAT 3 has much lower frequency response per pair than CAT 5. A good cable tester can actually verify that for me if you can get your hands on one (see network analyser). Just from looking online, CAT 6 has a minimum 250MHz bandwith while CAT 5 has a minimum 100 MHz bandwith per pair. http://www.lanshack.com/cat5e-tutorial.asp check here. It says CAT 5e is the same as CAT 6 but CAT 6 is manufactured to a higher standard. I guess that the fab tolerances are tighter for Cat 6.