STP vs UTP 1

[Guest_imported]

Because of many perturbating factors (high-voltage cables, high-voltage boxes,electrical engines),I need to use STP cat 5 cable instead of UTP cat 5. I have never used this type of cable.Is it compatible with RJ45 connectors? Is it compatible with HUB/SWITCH RJ45 ports? Do I need special HUB/SWITCH ports and special connectors? How do I make the the grounded?
Thank you!

 

[jimbopalmer]

there is NO standard for ethernet over shielded twisted pair, ever.

if UTP will not do the job, I suggest multimode fiber, there IS a standard for that. I tried to remain child-like, all I acheived was childish.

 

[ChrisAC]

Multimode fibre would be great is all your workstations had fibre NIC's and your switch was kitted out with duplex fibre ports for each LAN device! Sadly, in the real world this is not the case and copper is the prevalent method for distributed networks with fibre being used for switch to switch connections.

So, in answer to the original question, yes you can use STP cable rather than UTP if you feel that the installation is likely to suffer from high voltage cables etc.. I would suggest that you try to choose routes that avoid this kind of thing but in certain circumstances it can't be avoided. For example, I was involved with an installation in a factory environment where all the copper cabling had to be run through areas with a high density of factory machinery! I also did some work in Europe (Berlin, Zurich) where I found that STP was the standard cable being used in most installations.

The RJ-45 plugs are exactly the same as with UTP but the patch panels and outlets etc are different. It would be best to discuss this with the supplier of your cabling materials who should be able to assist you in choosing the right materials for the application.

Good luck.

Chris.
************************
Chris Andrew, CCNA
chrisac@gmx.co.uk
************************

 

[wybnormal]

I have a FAQ here in this forum which links back to the author of the CAT 3-4-5 standard. He is dead set against STP and have the science behind him to back up the opinion. It makes interesting reading.

BTW.. HV and shielding is a very bad idea unless you EXACTLY what you are doing with the grounding.

All this came up with a fight with Sieman's engineers over an installation of a new CAT scanner.. I pointed out that their own standards body in Germany did acceptance testing of Lucent CAT5 to 600Mhz and it passed in the UN shielded state. We used TWP and it worked just fine.

There many issues with STWP, bend radius is one, breaking the shield which causes leakage, dimished length due to signal antentuation, the need of shielded connectors, jacks AND equipment or it's all for nothing and so on..

MikeS
Find me at

http://www.packetattack.com

"The trouble with giving up civil rights is that you never get them back"

 

[Guest_imported]

Some interesting comments above relating to the original question...

I'd have expected there to be some benefit in say, using a single run of STP through an electrically noisy environment, provided the screen was efficiently earthed at both ends.

At the moment I have a mixture of UTP and thin ethernet on a home network. When I run a transmitter with an aerial that's located fairly close to the network, this causes the hub with the ethernet connection to throw a complete wobbly! Earthing the end of the coax by the hub completely cures the problem.


ROGER - GØAOZ.

 

[wybnormal]

Roger- I would agree in the *normal* design of things like coax.. and yes, I've shielded(??) a few PCs with tin foil at times

But.. as it was explained in the article, the TWP works by differential design.. ie.. each pair is a + and - signal.. twisted they cancel out the crosstalk. Almost like how white noise cancels out background noise.. The issue with shielding is the twisted cable CAT5 spec is designed to emit some of the noise.. the shield forces it back into the cabling.

The biggest problem is getting it installed properly. Perhaps it's different in Europe, but here in the states, I have yet to meet a cable installer who really *knows* how to work with shielded cable. And that is the real crux of the problem. There are so many parts that must work properly for the shielding to be effective and not become another problem.

I do remember working on some cabling for some *black* govt projects and we wired up some skifs.. normal TWP cable ran in conduit with brass wool as a packing.. the conduit was grounded to the overall shielding structure. That worked very well.

MikeS
Find me at

http://www.packetattack.com

"The trouble with giving up civil rights is that you never get them back"

 

[Guest_imported]

Yes Mike, I agree with what you say... I am not a cable installer by trade, and have never used STP, but I can fully appreciate the expertise required for this product to be fitted properly to ensure maximum screening.

Tin foil is darned useful stuff! I fitted a transmitter in a Citroën estate car once and all the electronic door locks jangled up and down in sympathy with my SSB transmissions! Wrapping the central locking electronics in foil and earthing it thoroughly cured the problem.


ROGER - GØAOZ.

 

[jimbopalmer]

Given that Chrisac lives in a real world where his boss does not flinch that he is proposing a solution with no standards body approval, that invalidate his warrenties, and has no vendor support from any source, how do we help him? I hate to suggest token ring, which DOES support STP, it is awfull late in the life of token ring to buy into that. I tried to remain child-like, all I acheived was childish.

 

[fonman]

Rather than STP, bite the bullet and build an infrastructure of EMT. Properly grounded, you get the benefits without the drawbacks.

 

[ChrisAC]

Jimbopalmer,

Did I upset you?? I was simply replying to the fact that you suggested a fibre network as an alternative to an STP copper network when in most cases this isn't really a good alternative for a distributed network! Switch to switch links maybe, and I've done plenty of those!!

All I said was that it's commonly used in Europe!! Nothing more! I did some work at Colt Telecom in Berlin and Zurich where we were installing UTP for HP and Cisco. While we were there another cabling team came in from a local company and started installing STP. After talking to one of the guys in this team I found out that STP was installed far more commonly in Europe than UTP! This is in contrast to the UK where we don't touch it with a barge pole!! However, the fact is that it is still installed and the companies that supply the materials do uphold the warranties providing that it is installed correctly and tested to their satisfaction.

Having said that I agree that it is very difficult to install correctly and I also agree with wybnormal's point about the foil sheild forcing the noise back in to the cable! I have always used UTP and always will.

Enough!!

Chris.
************************
Chris Andrew, CCNA
chrisac@gmx.co.uk
************************

 

[wires]

Make your life easier, use fiber or install UTP in EMT. STP is difficult to get right and even more difficult to keep right.

 

[ChrisAC]

Amen to that!! ************************
Chris Andrew, CCNA
chrisac@gmx.co.uk
************************

 

[Mike39]

If there is no way of getting around not using STP, I would make one suggestion to you. I would only ground one end of the shield. This was recommended to me by an engineer on a project using essentially TP telephone cable. The rationale is that you are creating an antenna which pulls any induced voltage to a single ground. If you ground both ends, the ground must be exactly identical which is about impossible. If the resistance between the two "grounds" and true earth ground is different, then you can have potential between the two. It's no fun trying to figure out why you can measure a voltage between earth ground and the "grounded" end of your shield. Please keep in mind, this was on a project where cabling was run over several miles. Your dilemma would be if you had induced interference which was minute to detect but still enough to interfere with your normal signals.