Crimping CAT6 cables results in lower bandwidth than expected

I'm trying to make my own CAT6 cables, because I need specific lengths.

I've managed to create 2 "working" patch cables, but when I hook them up to my cable modem, both of them take a fairly long time to create a connection (a bit over 5 seconds). Their speed is also lower than expected: 90mbit, versus an off the shelf cable which achieves around 140mbit and connects immediately (theoretical maximum of my cable ISP is 150).

My question is: can you create CAT6 cables yourself and achieve similar bandwidth results as off the shelf cables? Or is this something only someone with a lot of experience can achieve?

If it is indeed perfectly possible, does anyone have any tips? Below is a closeup of one of the cables. The RJ45 jacks are 2-pieced and the wiring scheme is T568A.

I'm getting the impression that the pins are not completely making contact with the wires, but I can't figure out how to fix that. I tried turning around the duct holder for the wires before inserting it in the jack, but that cable didn't work at all. I squeezed as hard as I can on the crimp tool, but to no avail...

my cable

Stefan Billiet

Posted 2013-12-31T11:36:05.590

Reputation: 253

6Have you used a cable tester on them? – mulaz – 2013-12-31T11:58:01.840

2Yes, crimping your own CAT6 cables usually results in lower bandwidth than expected. – Andrew Larsson – 2013-12-31T18:15:04.550

2The wire ducts weren't pushed entirely to the end of the jack, so the pins weren't completely jammed through the isolation of the wires. And apologies for the off topic; this stack exchange seemed to lean closest to the subject as far as I could see. – None – 2014-01-01T15:18:37.043

8@AndrewLarsson That's ridiculous. There is nothing wrong with making your own cables if you know what you're doing. – Brad – 2014-01-02T09:11:01.410

Answers

Ethernet does a signal to noise ratio test on the cable before bringing the link up. Since your homemade cable gives you approximately Fast Ethernet results, it is likely that the link negotiated to 100M instead of 1GE. If true, that itself is an indication of sub Cat6 results (in fact, sub Cat5e results). This chart summarizes what Cat5e and Cat6 are capable of:

Cat5e vs Cat6

Gigabit Ethernet has different cabling requirements than FastEthernet. Both Cat5e and Cat6 cabling requires all eight pins to negotiate at GigabitEthernet speeds. If only one of eight pins in the RJ45 mod plug aren't good, you're forced to 100Mbps (FastEthernet).

As you can see, Cat5e cables are capable of GigE speeds, and they aren't difficult for an amateur to build. I would remake the cable; this Cat6 termination video does a much better job explaining than I could. Keep in mind that because of the difference in Cat6 conductor sizes, true Cat6 is about four times harder to terminate than Cat5e.

I usually unkink and straighten a little less than a mod plug's length of wires with the side if my strippers before inserting into the plug. Your picture shows a good jacket termination, but I'll just mention that the jacket should get crimped into the mod plug as well. Cat5e and Cat6 standards require no more than 1/2 inch (1.27 centimeters) of untwisted cable in the mod plug when you terminate it; keep that in mind as you trim the cable before inserting into the mod plug. Also, be sure you're using real Cat6 certified mod plugs and cabling; there is a big difference in the Cat5e and Cat6 hardware.

Responding to your comment:

Thing is that the "G" light still never comes on. I thought that Cat6 is alway GigE, so I must be doing something wrong still... The wires do work and achieve approx. the max speed of my ISP now.

There seems to be a bit of a misunderstanding...

Both Cat5e and Cat6 are capable of GigabitEthernet; Cat6 results in a better cable with fewer errors, and you can run 10GE over short distances with it.
Nothing about Cat6 requires an ethernet link to negotiate to GigabitEthernet. If the hardware only supports FastEthernet, that's the most you'll get.
There are two likely speeds that your equipment operates at: FastEthernet (100Mbps) or GigabitEthernet (1000Mbps). Since your ISP rates are over FastEthernet, and you're getting those speeds now, it sounds like your link is operating at GigabitEthernet; however, I can't comment on your switch's "G" light.

Mike Pennington

Posted 2013-12-31T11:36:05.590

Reputation: 2 273

1If I may ask, why is Cat6 so much harder for an amateur? The jacks are 2 pieced (the jack itself and the wire duct), and once I realized I had to push the wire duct all the way to the end of the jack, all 8 wires make contact according to the cable tester. The sleeve is inserted a bit into the jack as well. Thing is that the "G" light still never comes on. I thought that Cat6 is alway GigE, so I must be doing something wrong still... The wires do work and achieve approx. the max speed of my ISP now. – Stefan Billiet – 2014-01-01T19:48:57.680

3@StefanBilliet, Cat6 is harder, because Cat5e uses smaller conductors than Cat6. Cat5e uses 24-26 AWG wire, and Cat6 uses 22-23 AWG wire; this makes Cat6 stiffer, and harder to work with. Cat6 terminations are also more sensitive to errors. I updated my answer with a video, perhaps that will help – Mike Pennington – 2014-01-02T08:28:40.310

The "G" light is usually (from my experience) used to test the grounding in shielded twisted pair.

You will also have problems if the cable you're trying to crimp onto is solid core vs stranded copper. The stranded copper is used for patch cables whereas solid core is used for structured cabling (patch panel to port) and is connected with punchdown blocks instead of RJ-45 tips.

Avery Abbott

Posted 2013-12-31T11:36:05.590

Reputation: 161

1It's pretty unusual to find shielded ethernet cabling outside of industrial applications... I have never seen it in consumer applications. It would make a bit more sense to me if that "G" meant something other than grounding. – Mike Pennington – 2014-01-02T18:50:14.857

http://www.extron.com/product/product.aspx?id=rj45ctr&allparts=1

DoD uses STP for some sensitive communications. The STP RJ-45 plugs have metal plating which is attached to the sheathing of the cable to establish a ground across the entire length of the cable. The only time I've seen the "G" light up on a cheapo tester is when testing these cables. Other than that, even a good factory-made cat6 cable won't light up anything other than 1-8. The cheap cable testers are merely continuity testers, nothing more. G for Ground makes a little more sense when you put int perspective.

– Avery Abbott – 2014-01-02T21:25:18.923

1My point was that he is asking on [su] as a consumer. Thus the chance of using shielded ethernet is pretty low – Mike Pennington – 2014-01-02T21:38:17.073

I think @AveryAbbott is right; the OP in this thread (http://superuser.com/questions/341527/why-g-does-not-light-up-in-network-cable-tester) seems to have the same cable tester as me. At least the wording of the manual is the same, though I can't check now, since I'm at work.

– Stefan Billiet – 2014-01-03T07:54:07.890

I upvoted both given answers since they clarified a lot. However, the problem turned out to be that the wire duct of the jack, containing the individual wires, was not pushed all the way to the end. You can see it a little in the picture; the wires sit crookedly.
Once I realized that, I clipped the wires so they didn't extrude from the wire duct, made sure the open side of the wire duct was facing the pins, pushed the wire duct all the way to the end and crimped with the crimping tool. Now all the cables work :-)
Thx everyone for your help and input.

Stefan Billiet

Posted 2013-12-31T11:36:05.590

Reputation: 253

From my experience, with a quality crimping tool (mine is the ratcheting type), 5e vs 6 doesn't make a difference. Further, I have a lot of CAT6 cable & I've built runs with 5e and 6 jacks & haven't noticed a difference in performance. I do look to ensure the ends of the conductors are near the wall of the plug. I've found often it takes 2 tries to get them perfect, so I shove in like I'm going to crimp, pull the cable out, retrim the wires, and repeat. – Chris K – 2014-01-07T07:02:14.750