Does patch-panels affect network speed?

brunogirard1970 · 2008-06-20T20:59:28+00:00

Hello,I am in the process of designing a mid-size network (~300 connections)and I play with the idea of having 2 levels of patch-panels.My physical design is based on the idea of not having to modify theservers room (walls, roof, floor, concretes, etc.) if new cables areeventualy required in the building. Between the server rooms and thebuilding, we would therefore add "transit" patch-panels, with ease ofaccess. The connections between the servers room panels and the"transit" panels will contain 576 wires to cover the expected cablinggrowth. All users devices would be connected to transit panels.Concretely speaking, it means that a desktop user will reach itsswitch trough 2 patch panels exept of one. Will that affectperformances? You can take for granted that crimping will be doneprofessionally and that all panels are cat 6.Thank you,B

Jun 20, 2008 27 Replies

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Doug McIntyre 18 years ago

Yes. A professional punchdown shouldn't have that much untwisted wire.

No, never use shielded cable for ethernet.

For whenever 10GBase-T copper switches will be afordable (right now, its $1000 a port), plain Cat6 will support 10Gbps speeds at up to

55m. You need Cat6A cabling to reach 100m at 10Gbps. At that point, you need to have Cat6 patch panels, and Cat6 patch cables as well. Regular Cat5e patch panels and patch cables will fail. There's never going to be pulling them out and reterminating, any professional cable person will pull new cable for new panels.

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Doug McIntyre 18 years ago

I've gone into a few situations where exactly that did happen. Split pairs, and the interface only links up at 10Mbps. Fix the split pairs, and it works at 100Mbps with no gear (or config) change.

And there have been many posts over the years to this group with people coming here with that exact same problem.

I'm not saying that it happens all the time, but it does happen from time to time.

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brunogirard1970 18 years ago

Why?

I already have cat6 patch panels and cat6a cables. Everything is set for future 10g-ethernet.

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Doug McIntyre 18 years ago

Nobody grounds the shield correct. The specs were all written for UTP. The balanced driven pairs of Ethernet are very good at avoiding noise. The shield (even properly done) often attracts more noise into the circuit than UTP does by itself.

STP is for applications that aren't balanced drivers. (ie. RS232 serial data).

At the prices you previously quoted? Those are some amazingly cheap Cat6 patch panels..

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brunogirard1970 18 years ago

If it is only a question of grounding, I am not nervous. The place I work at hire a couple of electrical engineers ... I should be OK to find a grounder among them.

Beside, what you say surprises me. I see many articles about the pros of using STP for lan purposes.

A cat6 96 ports patch panels is around 125$.

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Robert Redelmeier 18 years ago

Which way do you consider correct? Tie both end and live with the ground loops? Tie one end (which? head? or stn?) and ground the other through a resistor/cap (which)?

Originally, yes.

Maybe. I've seen radiation from 100 onto NTSC ch 2. If STP is so worthless, why is so much of it installed an Europe? Wouldn't the EMI test be easy to pass? And if STP is so worthless, why is it even available in N.Am where EMI tests are rare?

Certainly more necessary there. Not worthless for ethernet.

-- Robert

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lawrence.jones 18 years ago

Only through a freak of nature. For the umpteenth time, the autonegotiation protocol is always done at 10Mbps, it does not have any kind of cable test (other than that the two ends have to be able to communicate in order to negotiate), and it does not have any kind of fallback other than, if the two ends can't communicate, the assumption is that the other end doesn't support autonegotiation/100Mbps so then the link falls back to 10Mbps. So, the only way to get a fallback to

10Mbps is if the link is so bad that autonegotiation fails, which means the link doesn't really work at 10Mbps, either. If the split pairs only affect one direction and the majority of the data transmission is in the other direction, then it's possible that you won't notice how bad the bad direction is unless you specifically look for it.

-- Larry Jones

The hardest part for us avant-garde post-modern artists is deciding whether or not to embrace commercialism. -- Calvin

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