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We are going to do the cabling in our new office building and we are thinking to lay down 10Gbit cables since we use HP switches that come with 10Gbit ethernet ports. We will also lay down few fiber optic cables, just in case :).

What we are wondering now is should we use CAT6e or CAT7 cables for 10Gbit? Are they backward compatible, i.e. can we use them with 1Gbit swiches/PCs/Servers?


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closed as not constructive by ewwhite, Chopper3, Jenny D, Aaron Copley, Ward Apr 19 '13 at 13:36

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5 Answers

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Not an "answer" per-se, but just to keep the standards straight...

Cat5 - 100Mb @ 100m
Cat5e - 1Gb @ 100m
Cat6 - 1Gb @ 100m
Cat6a - 10Gb @ 100m
Cat7 - 10Gb @ 100m (Uses GG45, not RJ45)
Cat7a - 10Gb @ 100m (Uses GG45)

Cat7a is expected to be standardized for 40Gb @ 50m and 100Gb @ 15m (but no such standard currently exists, there is no guarantee there ever will be). With advancements in circuit technology Cat7a is predicted be standardized for 100Gb @ 100m someday (again, no guarantee). Cat7 is officially known as CatF, and Cat7a as CatFa; no idea why they did that. I've seen cables advertized as Cat7/Cat7a without the GG45 ends, these are almost certainly just Shielded lower grade cables (especially since there is no "7" yet, there is no official meaning to which manufacturers would have to adhere).

Also noteworthy: Cat6a is about 5x more expensive than Cat5e.

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In short, use Cat6. –  ewwhite Apr 19 '13 at 13:22
I think you mean Cat6a, the 10Gb stuff. I would generally agree with that for new installations, yep. –  Chris S Apr 19 '13 at 13:24
FWIW -- I've run 1gb on cat5 and I've run 10gb on cat5e that I made myself. That is actually one of the things that makes me really wary of these standards and the actual installs. The standards make it so a catX install will work in all situations -- reality is worse -- it will work when you "test" it with a couple nodes then act weird when you add the 80th node to the network. –  chris Apr 19 '13 at 16:54
Eh, this isn't mystical or something. The standards specify what scientists guarantee will work. It's well known to them that cables of lesser quality work at shorter lengths. Additionally higher 'quality' endpoints enable cleaner signal generation and detection, allowing lower quality cables and longer lengths to work. This is great fun and all - until you're selling a product to a 3rd party and making a financially-backed guarantee that it will work. –  Chris S Apr 19 '13 at 17:14
I think you misunderstand -- the "Standard" only works if you've tested the whole cable install. Port to port. If your vendor doesn't do a full test, or if you substitute a non-cat6a cable as a patch cable, or if the structured cabling gets roughhoused because someone has to replace a switch -- you'll easily wind up with a non-cat6a install that still works at 10gb, but not always, such as maybe when you've plugged your 30th 10gb node in, long after the incident that actually degraded the cable. –  chris Apr 24 '13 at 2:53
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I'll take a contrarian view here.

There is nearly no value in going from cat5e to cat6a in almost all office environments.

10gb copper is nasty, expensive, and flakey. It uses far more space than 5e, is heavier, and is harder to install. You have to fully test the entire cable plant including your patch cables if you want it to work. And by test I mean "use a cable tester" not "plug a computer in and watch a link light come up". And it gets you nothing unless you're going to actually run it at 10gb -- because 1gb works just fine on the cheaper stuff and doesn't work better on the expensive stuff.

If you're going to be going 10gb/sec because you have legit reasons (you do geology / video / VM image work / etc) -- skip the copper. Go straight to fiber. But even that only gets you 10gb because the 40gb standard requires 4 pairs per link.

Another option is to only wire up those specific ports that actually need the 10gb over copper and just use 5e for everything else. Otherwise you'll be spending 10x as much money as you need to for those VOIP phone ports.

If this is a greenfield deployment just have them run conduits and leave cable pulls in place -- that way you can pull what you need right now and replace it with what you need later, rather than spending a huge amount of money installing FDDI and ATM everywhere.

No great choices...

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Cable category garanties you that your cable fits some requirements in terms of bandwidth and capacity, it doesn't tell you anything about the transmission medium (It could be coaxial, twisted-pair of copper or optical fiber.

Category 6a operates at a frequency of 550 MHz and is backward compatible with the existing standards. This technology is suitable for industry sectors utilizing high performance computing platforms to support very high bandwidth intensive applications. 10G/Cat 6a applications would initially be deployed in server farms, storage area networks, and data centers. It supports 10G

Cat 7 is likely to have a natural death as it is unadaptable, have issues in installation and cables ought to be re-pulled

I would definitely select CAT6a instead of CAT7.

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Cat7 has different plugs, make sure you get ones with GG45 connectors, as they are backwards compatible to RJ45 (8P8C).

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Despite what the Wikipedia article says I'm pretty sure a cable wired for the new standard will not work in an older socket. And older cabling only works in an "active" GG45 socket. –  Chris S Apr 19 '13 at 13:22
@Chris S Not just wikipedia, cabletool.net/Kerpen/Data_System_Cable/82.PDF but I haven't had much of an opportunity to test said compatibility. Maybe I should change the text to read GG45 jacks. –  NickW Apr 19 '13 at 13:29
I don't own any GG45 equipment yet. Someone just showed my a Cat7 cable once with the GG45 connector on it, it only had pins 1/2 and 7/8 on the RJ45 side. Pins 3/6 are necessary for 100Mb use in an RJ45 socket; all the pins are needed for 1GbE. But I agree the marketing says 100% backward compatible all over the place. –  Chris S Apr 19 '13 at 13:52
Wouldn't be the first time marketing had no bearing in reality :) –  NickW Apr 19 '13 at 14:12
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As a rule of thumb - always plan for the future. No reason not to lay CAT7 if it's a backbone infrastructure you are talking about.

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Putting the money saved by using Cat5e in a savings account would likely pay for more than just installing Cat7 cable by the time they actually need those speeds. Planning for the future isn't just buying the best available right now, but balancing the costs and benefits, especially with such long times involved the time value of money must be considered as well. –  Chris S Apr 19 '13 at 13:19
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