Short UTP CAT-6 Xover?

[technicalbloke]

Hi there,

This is my first post here so hello all!

I have 2 servers sat side by side in an installation I am planning and I want them to talk to each other as fast as their gigabit cards will allow (naturally). I planned to link them via a 1m UTP CAT-6 crossover cable but my supplier only has 25m ones in stock ATM. Now although I'm not going to be building this for at least a few weeks it's made me realize I have some questions I can't answer and, maybe I'm being dumb but Google isn't proving much help either. They are...

A) If cable length makes any measurable difference to top speeds in low EM noise situations?

B) If, for a 1m distance such as this, STP CAT5e would prove significantly slower than UTP CAT6 in practice?
(significant being a few percent)

C) If the cards NICs can auto-detect cable type would there be much performance hit using a patch cable instead of a crossover?

None of these are crucial issues as I will be getting the cable I intended anyway (unless I encounter a good reason not to) but I would be interested to hear any answers.

Kindest regards,

Roger Heathcote.

 

[jimbopalmer]

Gigabit auto-detects polarity and corrects for it in the standard, so while you may use cross over cables, you do not need to.

A) not from 2 feet to 328 feet, the limit of the standard.

B) Correctly installed Cat 5, Cat5e, Cat6 and Cat 6A will all do 1000baseT with the same speed from 2 feet to 328 feet.

C)If they are truly 1000baseT compliant, they will correct polarity with no decrease in performance.



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

 

[AWGoodson]

It wont be the same speed 2 feet to 328 feet if you are using patch cords up to 328' long! This only applies to solid copper cable not patch cords.

Allan Goodson
Estimator
3D Datacom, Inc.

http://www.3ddatacom.com