I have three network switches, all gigabit, from DLink and TPLink:

  • 1x 4-port
  • 2x 8-port

Connecting to these are 5 laptops and 2 desktops, all with gigabit NICs:

  • 4 Realtek
  • 1 Intel
  • 1 AMD
  • 1 unknown

The network has 4 45' runs and 4 60' runs.

All computers will only connect at gigabit speed when the runs are less than 30'.

I've tried 4 different cable brands, all riser-rated Cat 5e from Hitachi, Frisby, Webtrack, and one unknown brand. I have re-tipped the cables several times. I've used keystone jakcs at both ends with pre-made cables. I have used a 24-port patch panel with pre-made cables at the ends. I have tried PC-to-PC. I've played with the hardware settings.

I have not yet tried Cat 6. I've ordered it but the shipment is delayed currently.

I was able nail down 30' as the success point by starting with a 75' cable, testing it, and then cutting 5' off the end until the the systems connected at gigabit.

The problem is that none of my runs are shorter than 45' and so obviously 30' won't work in the environment.

Does anybody have any ideas as to what may be causing this issue?

  • 1
    Cat5e may be rated for gigabit, but in my experience it isn't very good at it. You should have better luck with the cat6. It is peculiar to have them all fail at gigabit speeds at exactly the same length marker though. – MaQleod Oct 4 '11 at 14:23
  • 1
    I've been using Cat5e 350MHz 5' to 100' for several years now on a gigabit network. Each client machine is using the Cat5e and I use Cat6 from the servers to the switches. – kobaltz Oct 4 '11 at 14:53

What is the frequency rating on your Cat5e? There are two different types 100MHz and 350MHz. You may also want to check where the wires are running because there could be interference in the lines. Also try a different Ethernet port on your switch.

Cat5 = If you plan on running at most 100 Mbps
Cat5e = If you plan on running at 1000 Mbps (1 Gbps)
Cat6 = If you plan on running at 1000 Mbps (1 Gbps) or more. Cat6 is better if you are in areas that have lots of interference like near power lines, lights, manufacturing equipment, or a long distance 1000 Mbps (Gigabit) run.
We advise that you run at least Cat5e or Cat6 cable in the walls
Cat5e are great for patch cables from the patch panel to the switch or from the computer to the wall jack
We very rarely use Cat5 cable anymore.
For most applications the CAT5E 350MHz network cables are best. They will run up to 1 Gig and are not as expensive as CAT 6 cables.
CAT 6 cables are great for "future proofing" your installation. They are rated to carry network speeds above 1000 Mbps (Gigabit).
CAT5E 100MHz are rated to only run up to 100Mbps networks but are inexpensive.

Article Source: http://EzineArticles.com/322715

  • They are all solid core. I can confirm 2 of them are 350MHz 1 states 550MHz but that was from ebay. I want to go cat 6 I am limited on funding seeing as its a home install. I can get 1000' cat6 from ebay for 80-100 but not sure of quality. At runs less than 20 meters I didn't think it would matter that much. I really like to have more confirmation before going out and spending another $100. Especially since I have combind 2700' of 5e. Thanks. – Peter Oct 4 '11 at 15:18
  • I doubt the one is 550MHz. That's ebay for you. However, the other two that are 350MHz should work on distances further than 30'. Have you checked your router/switch for a firmware update that could have addressed the issue? I'm thinking that the issue is with either the connections (make sure you're using the correct pin layout) and/or the switch. – kobaltz Oct 4 '11 at 15:22
  • well I am now leaning towards hardware. just tested 3 55' rj45 tipped cables with 2 cisco 3560s gig. seem to work fine. This is rather annoying. – Peter Oct 4 '11 at 16:01
  • Check the firmware on the switch. You many be able to restore it back to factory defaults if you had any custom scripting. – kobaltz Oct 4 '11 at 16:04
  • Unfortunately the 2 switches I am having the issues with are un-managed and have no options. The part that gets me is the issue happens crossover PC to PC with several machines. The router I am using is a TP-Link gig/wireless N with DD-WRT. latest firmware. Another thing that is so annoying is ALL the devices worked fine a few weeks ago before I moved. All connected at gig speeds but the max run then was 15' and it was single prefabricated lines. – Peter Oct 4 '11 at 16:14

It might have something to do with stranded vs solid wires in the cable. Stranded is more flexible but has higher attenuation levels. The 100 meter length for GB ethernet is based on 90m of solid, and 10m of stranded wire. Using stranded cable for a longer runs will reduce the maximum length although I can't find anything explicitly stating by how much.

If all your different wire vendors used stranded cabling and have equivalent attenuation rates having them all drop down to 100MB at the same point would be reasonable.

  • Makes sense. They are all solid core though. – Peter Oct 4 '11 at 16:05

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