Gigabit Network cables

[ukmgranger]

Can I use standard RJ45 cables with a Gigbit network?

[kltye]

RJ45 is the jack used for Ethernet (Registered Jack). You're probably referring to Cat5 cables, and for Gigabit, you should use Cat5e. Cat6 usually bring no added benefit, especially for the cost.

[sleonard]

They must be Cat5e or better. Cat 5 is rated "only" to 100 Mbit. Cat4 to 10 Mbit. All are "Standard" RJ45 cables though.

[ukmgranger]

Sorry about that - my terminology was pants there!

Yes I did mean Cat5.

Looks like I'm going to have to replace a small length of cable that goes between the RJ45 socket in my lounge and the socket to my server in another room. Bummer.

Still should be worth it for the extra bandwidth.

[waynedunham]

I recently upgraded to Gigabit on my wired home network. Luckily a couple years ago when I wired the house I decided to spend the extra $$ and go with 5E rated components, wires and patch cables.

When I got the Gigabit switch I just swapped it out for my existing 10/100 switch. Everything worked without any hitches or setup required. I then ran some tests sending/receiving between my machines. I still had one machine that only did 10/100, so I could see the difference between 10/100 and Gigabit. All I can say is...
Sure makes a HUGE difference when you're transferring that 6gb recording from one machine to another!

[src666]

I've heard of mixed results using Cat5E. The "standards guru" at work says that GigE is (usually) limited to 600Mbit on Cat5E, but will go to full Gig on Cat6. Basically, it really depends on how well made the cables are, and also how well terminated the jacks they plug into are.

I'm running GigE over Cat5E at home, and while I haven't done serious testing to push the limits, I also haven't had any trouble with any of the existing cables/terminations.

[dagar]

Actually your biggest limitation is the PCI bus. 32bit PCI can't run nearly that fast (600mbs) but it will run faster than 100mbs

Cat6 is a fussy ... thing (to say the least) as the tolerances are much tighter (for run length, termination unpairing, bends at the jack, etc.)

If you have high quality Cat5 cable you can (in theory) go faster than 100mhz (some Cat5 cable is rated at 350mhz). It will depend upon how well your GbE gear can handle errors due to noise. YMMV. Caveat emptor (and all that jazz )

[blade]

Originally Posted by dagar

Actually your biggest limitation is the PCI bus. 32bit PCI can't run nearly that fast (600mbs) but it will run faster than 100mbs

Are you sure that's correct? I thought in theory the PCI bus could handle 127.2 Mbytes/Sec isn't that greater than 600 mbits? Or are you talking about actual real world performance?

[dagar]

Real world performance. Most of the implementations that use the PCI bus can't reach it. Which sucks. But yeah in theory they can. Also would depend upon bus loading which is why some of the more robust server boards have multiple PCI controllers.

Yeah so 127MBS is around 1000mbs which is about 200mbs shy of the 1200mbs that GbE is at 'line rate'. GbE is marketed with the Ethernet framing overhead removed; which was a departure from 10mb and 100mb Ethernet variants.

All of those values are simplex on the Ethernet side. I love (not) how some try to market FE products as 200mbs and GbE products as 2000mbs/2gbs And the max theoretical goodput you can get on a 10/100 base link is closer to 70% than 80% (most things will say 80% but an Ethernet bus will have issues at 80% loading which would max the bus out when you add in the framing overhead).

[blade]

dagar, thanks for the explanation.

[dagar]

lol, np glad it was understandable ... Geogecko, one of the regulars at htpcnews, say I'm the Charlie Brown teacher