Posted by: robricc
Gigabit ethernet over Cat. 5e - 07/05/2004 10:16
Does anyone know off-hand how long you can run Cat.5e cable and still maintain Gigiabit speeds? I am trying to decide to wire my house with 5e or 6.
Posted by: belezeebub
Re: Gigabit ethernet over Cat. 5e - 07/05/2004 10:40
Here is a summary of the various maximum segment length defined for Ethernet. length are valid for networks with only one repeater or repeating hub. Further analysis is required for networks with more than one repeater.
Standard
Maximum Cable Segment Length in Meters
10Base5
500
10Base2
185
10Base-T
100
10Base-FL
2000
100Base-TX
100
100Base-FX
400
100Base-T4
100
100Base-T2
100
1000Base-LX
550 if 62.5 µ or 50 µ multimode fiber3000 if 10 µ singlemode fiber
1000Base-SX
250 if 62.5 µ multimode fiber550 if 50 µ multimode fiber
1000Base-CX
25
Posted by: robricc
Re: Gigabit ethernet over Cat. 5e - 07/05/2004 11:40
Maybe I'm missing something, but I don't think this answers my question. I'm talking about Gigabit over copper.
Posted by: wfaulk
Re: Gigabit ethernet over Cat. 5e - 07/05/2004 11:59
Yeah. None of those gigabit standards are for UTP. There's 1000baseT and 1000baseTX, I believe, with 1000baseT being much more common. (I'm not sure TX has even been ratified yet.) The max length for a run is 100m using Cat5 or greater, but it requires all four pairs, so make sure your installer doesn't cut corners by running only two pairs.
Posted by: Phoenix42
Re: Gigabit ethernet over Cat. 5e - 07/05/2004 12:05
I'm getting the strong impression that it is limited to 100m irrelevant as to whether you use 5e or 6.
http://compnetworking.about.com/library/glossary/bldef-cat6.htm
http://www.foundrynet.com/services/faqs/GigCopper.html
damn, slow typing
Posted by: tman
Re: Gigabit ethernet over Cat. 5e - 07/05/2004 12:41
There are more stringent limits on bend radius and how much you're allowed to untwist at the ends when doing gigabit over copper.
Posted by: robricc
Re: Gigabit ethernet over Cat. 5e - 07/05/2004 15:20
The max length for a run is 100m using Cat5 or greater...
Hmmm. I tried using plain-old Cat5 once and it simply wouldn't link. This was only about 3ft. cable length too.
Then again, all my gigabit stuff is bottom of the [price] barrel.
Posted by: wfaulk
Re: Gigabit ethernet over Cat. 5e - 07/05/2004 22:29
Are you sure all four pairs were connected and working properly? Only two pairs are used for 100baseTX and 10baseT.
Posted by: lectric
Re: Gigabit ethernet over Cat. 5e - 08/05/2004 09:00
It also matters if the pinout was correct. Remember, Pins 1-2, 3-6, 4-5, 7-8 should be twisted together. Pin 1 is on the left when looking at an end with the retention clip away from you.
Posted by: mlord
Re: Gigabit ethernet over Cat. 5e - 08/05/2004 09:17
Eh?
1-2 3-6 4-5 7-8, ne c'est pas?
Posted by: lectric
Re: Gigabit ethernet over Cat. 5e - 08/05/2004 09:36
OK... I give up. What's that in english?
Posted by: mlord
Re: Gigabit ethernet over Cat. 5e - 08/05/2004 09:41
It means, is it not so?, ne c'est pas?
Posted by: lectric
Re: Gigabit ethernet over Cat. 5e - 08/05/2004 09:48
Ah, well I hope so, but I've seen too many people wiring improperly. And 10 or 100 BT is more forgiving.
Posted by: robricc
Re: Gigabit ethernet over Cat. 5e - 08/05/2004 10:58
I can't be certain that the cable was still good, but when I made it it was.
Posted by: wfaulk
Re: Gigabit ethernet over Cat. 5e - 08/05/2004 11:52
My point is, how do you know? If it worked fine for regular or fast ethernet, that doesn't prove anything about half of the cable, and if it once worked with gigabit, you wouldn't be asking the question. Unless you tested with a tester that checked all four pairs, there's no way to know if it was a good cable or not.
Regardless, the spec (802.3ab) says Cat5. Period. Not even Cat5e. As Trevor pointed out, the ends of the cable may have been untwisted too much for gigabit. Or if it was a homemade cable, the data pairs may not have been the twisted pairs.
That said, it's possible that Cat6 cabling might give you more leeway than Cat5. That is, it may be that you can make zero mistakes with Cat5, but you can make a few with Cat6. I don't know. That's just conjecture.
Posted by: robricc
Re: Gigabit ethernet over Cat. 5e - 08/05/2004 12:37
Unless you tested with a tester that checked all four pairs, there's no way to know if it was a good cable or not.
That's what I meant when I said it was good when I made it.
I think I should probably just go with Cat.6 to be safe. Unfortunately, I haven't seen something
like this with Cat.6 in it.
Posted by: tman
Re: Gigabit ethernet over Cat. 5e - 08/05/2004 13:13
The cheap cable testers aren't to be trusted too much. They only check for continuity through each individual wire. I know somebody that spent days fiddling with a cable run because it would refuse to run at 100baseT. It turns out the person that installed it had gotten some of the wires mixed up and they weren't paired properly. The cheap cable checker said it was fine and was wired up correctly however.