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Author Topic: OT Network question....  (Read 11397 times)

Tommy Peel

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Re: OT Network question....
« Reply #20 on: June 13, 2014, 03:58:47 PM »

What I'd do is grab another Gigabit switch and plug one of the PCs directly into it with a new patch cable, bypassing any installed wiring. If you get a GB connection, it's probably a cabling issue. If it connects at 100Mb, it's probably a settings issue. If you have a crossover cables in the mix (terminated T-568A on one end, T568B on the other) that will likely force it to a lower speed. Crossover cables may not play nicely with Gigabit, since only two pairs are crossed and GB uses all four pairs.

However, I have seen where some NICs have trouble negotiating with some switches, and either they negotiate to a lower speed, they fail to negotiate altogether, or they link up at high speed but are slower than an ant crawling through molasses.

It very well could be some poorly terminated cables. It looks like most of their networking infrastructure is made of homemade cables. There is a patch panel in the cabinet with the switch. I have no idea how any of it is terminated. Probably I'll try connecting the existing switch directly to my MacBook or one of their computers and go from there... It might be a long day.

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Tommy Peel

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Re: OT Network question....
« Reply #21 on: June 13, 2014, 04:04:02 PM »

Another thought: is there a cheap network tester to verify that cables are wired correctly. I realize that truly verifying if a cable runs at a given speed takes an expensive unit. I'm mainly interested in whether it's electrically correct.

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Bob Leonard

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Re: OT Network question....
« Reply #22 on: June 13, 2014, 05:22:33 PM »

There's plenty available. Look for one that also tell distance to fault and will also tone the cable so it can be traced in a bundle or group of cables. Try Fluke, Palladin, etc.. For a low cost do a lot type of tester one of my favorites is the Lansmart. Here is a link to the Hobbes site and their products which can be found just about anywhere.

http://www.hobbes-europe.com/catalog.php5?catalog_id=2&language_id=2

« Last Edit: June 13, 2014, 05:27:49 PM by Bob Leonard »
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Jonathan Johnson

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Re: OT Network question....
« Reply #23 on: June 13, 2014, 07:34:03 PM »

Another thought: is there a cheap network tester to verify that cables are wired correctly. I realize that truly verifying if a cable runs at a given speed takes an expensive unit. I'm mainly interested in whether it's electrically correct.

One common problem with amateur homemade cables is mixed up pairs. Each pair of wires is a signal line, and if you mix them up you'll get the + of one signal with the + or - of another signal, or some such cluster. They may be wired the same on both ends, but that doesn't mean it will work properly. It would be just as if you were building an audio snake and terminated the red wire from channel 6 and the black wire from channel 12 into the jack for channel 3. Imagine the crosstalk! If you stick with one of the two accepted pinout standards, TIA/EIA-568 T568A or T568B, life will be a lot easier. I don't know how it is where you are, but in my neck of the woods T568B is the most common so that is what I use.

The cheap testers won't be able to tell you if there are messed-up pairs if the pinout is the same on both ends, because they only do a continuity test. More expensive ones do a standing wave test to determine the length, but that still isn't sophisticated enough to detect mixed up pairs. The cheapest tool to detect mixed up pairs is the eyes in your own head.

Another common problem is stripping away too much of the jacket and untwisting the pairs at the termination. I had one customer that had very poor network performance. I opened up the jacks and discovered that between 1 and 2 inches of the outer jacket had been stripped away and the wires untwisted. That was enough to impact performance. I reterminated them, keeping the jacket as close to the end as possible and maintaining the twist all the way to the IDC stab. Worked much better after that. When terminated with RJ45 plugs, the jacket should be inside the plug under the first strain relief.
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Tommy Peel

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Re: OT Network question....
« Reply #24 on: June 14, 2014, 11:27:06 AM »

One common problem with amateur homemade cables is mixed up pairs. Each pair of wires is a signal line, and if you mix them up you'll get the + of one signal with the + or - of another signal, or some such cluster. They may be wired the same on both ends, but that doesn't mean it will work properly. It would be just as if you were building an audio snake and terminated the red wire from channel 6 and the black wire from channel 12 into the jack for channel 3. Imagine the crosstalk! If you stick with one of the two accepted pinout standards, TIA/EIA-568 T568A or T568B, life will be a lot easier. I don't know how it is where you are, but in my neck of the woods T568B is the most common so that is what I use.

The cheap testers won't be able to tell you if there are messed-up pairs if the pinout is the same on both ends, because they only do a continuity test. More expensive ones do a standing wave test to determine the length, but that still isn't sophisticated enough to detect mixed up pairs. The cheapest tool to detect mixed up pairs is the eyes in your own head.

Another common problem is stripping away too much of the jacket and untwisting the pairs at the termination. I had one customer that had very poor network performance. I opened up the jacks and discovered that between 1 and 2 inches of the outer jacket had been stripped away and the wires untwisted. That was enough to impact performance. I reterminated them, keeping the jacket as close to the end as possible and maintaining the twist all the way to the IDC stab. Worked much better after that. When terminated with RJ45 plugs, the jacket should be inside the plug under the first strain relief.

I suspect that what's going on is a combination of all these things. Some of the homemade patch cables looked pretty bad; you don't want to see the network cabinet in the office.... Guess I've got my work cut out for me. I'll probably just skip the tester for now as they won't tell me very much.
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Steven Barnes

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Re: OT Network question....
« Reply #25 on: June 14, 2014, 11:41:49 AM »

Seems reasonable to me. The Ubiquiti gear works well. Using the same SSIDs and passwords simplifies roaming. I believe that you will need to designate one computer as a "controller" for the Ubiquiti access points; it will have software running that will manage the connections and ensure smooth roaming between APs. This PC will need to be powered on at all times.


A little late to the game on this one, but I essentially I have this same AP setup covering a 20,000sqft shop with great success. We are using the Unifi AP Pro with a different switch/router setup.

A note with the Ubiquiti AP, you will not need a designated computer for the controller up and running 24/7. You will need the software to configure them the first time, but after they are configured you are good to go. You will only need to software to do firmware upgrades or make changes to the AP. You can also tie them into an smtp server and they will send you emails if there are any issues etc.
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Re: OT Network question....
« Reply #25 on: June 14, 2014, 11:41:49 AM »


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