i have a situation 6

[phoneguy610]

Ran (1) cat5e cable from a network switch to a computer for a customer.

because of the situation there is no patch panel or jack on either end, rj45 on both ends.

tested the cable with my testers, tested OK

plugged in laptop, laptop got connection no problem

now there PC which works on any other cable, when plugged in does not get connection. Any ideas?

 

[iolair]

I'd check the NIC on the PC, especially the duplex and speed settings. I've seen them where the autodetect settings will not negotiate properly. I've had to set them manually.

Iolair MacWalter
Network Engineer

 

[SYQUEST]

It could also be the PC NIC does not have auto MDI/MDIX for "auto" crossover of the TX/RX pairs of the Ethernet, and your laptop probably does have that capability. If that is the case, it might be better to put jacks on both ends, and use short patch cords to connect to the devices, that would be the better way to do this and maintain some standards!

....JIM....

 

[edfair]

I've seen issues with connectors on solid wire failing where it was the wrong type of connector. It would work sometimes and not others.

I've also seen the connectors fail to make all connections if there was twisting stress put on them.

Ed Fair
Give the wrong symptoms, get the wrong solutions.

 

[FredWagner]

There are different types of RJ-45 connectors, for stranded vs solid cable. Did you pull solid cable, and use RJ-45's for stranded ?

Fred Wagner

 

[wires]

There are different types of RJ-45 connectors"

And some do both. For 5 and 5e I use Panduit MP588. No problems with either stranded or solid.

If the tester verified straight through pinout then it is likely a speed/duplex problem. There was a thread some time back where on a longer run a laptop worked and a NIC in a desktop didn't. I recall it was a problem the signal voltage level being too low.

Good luck!

 

[phoneguyjr]

Are the Cable ends terminated using either 568B or 568A? I have seen where a customer used a company to install a DVR for a security system to the network. They ran a Cat5E cable and tested it with just a wire-map tester. They had it terminated all wrong, but the same at both ends so wire-map said it was good. After the DVR wouldn't work, we were called in to find out why. We Scanned it with an Omniscanner and it would not pass a scan. Replaced the ends with the proper 568B wiring and guess what, it worked! A lot of people believe that as long as its the same on both end it will work, NOT SO! If it works at all its only going to be part of the time. If you have both ends 568B or 568A, then it may be a Kink in the wire somewhere. That will also cause errors that prevent things from working. Hope this helps.

 

[iolair]

One other thing I thought of - where I work, the engineer before me had split pairs in some of the cables. Definitely worked fine with the old 10baseT stuff, but when we went 100baseT, well..............

And I do agree with one of the above posts, the stranded/solid issue can be a real headache.



Iolair MacWalter
Network Engineer

 

[phoneguy610]

So i went back , i plugged cable into my laptop again and it worked and then plugged it back into customer pc and it still did not work.
(the customer replaced the NIC card before i got onsite so it was not that)

I tested the cable with different testers again and they tested ok.

I decided to just reterminate the Rjs on both ends and wouldnt you know it now works.

I guess we will never know but have a star all for your feedback

 

[SYQUEST]

The problem was most likely a crossover issue. I did mention it in my post above!

....JIM....

 

[FredWagner]

Phoneguy610 -
A point to remember, there is a reason for using jacks and patch cords - the patch cords use stranded cable, which is designed to be flexed, as it will be when connected to equipment, especially in offices. When solid cable gets flexed, eventually one of the wires will break, and fail open. You may save in the short run by not using termination plates/panels and patch cords, some you're building a problem for someone to solve in the future.
Years ago I inherited a situation where local people, not cable pros, rewired an office, using solid-wire cable, terminated directly. At one office, they'd had several yards excess, which they left on, just looped it into a big hank, and wrapped the hank around a steel stanchion for a cubicle, and secured it with a cable tie. Made a crude but effective iron-core inductor, which did check for continuity, but was very lousy at 100BaseT connectivity. Once I found it, we clipped it off to a proper length, put a termination jack on it, and used a patch cord to the PC. The customer's network connection was up to speed after that.

Fred Wagner

 

[phoneguy610]

Fred-

Believe me i agree 110%
The only reason i put an rj at PC end is because the PC will only be in that room temporarily while the neighboring room is finished. After that i will move the cable properly.

As far as patch panel, this was not my original job and when i came to add a cable, all of their existing cabling was terminated directly to the switch. I raised the option of moving everything to a patch panel but the customer did not want to pay for that.

So hopefully a full cabling job in the future right?

 

[FredWagner]

If it wasn't a crossover or 568A-568B issue, one simple expedient might be to use a small hub or switch, and plug the cable into that, and a short patch cable to the temporarily located computer.
and yes, if they're still in business, doing the cabling correctly should be in their budget! When furniture gets moved, and the cable to the PC gets bumped or crushed, it's so much simpler if you can just use a new patch cable between the PC and the wall jack, rather than having to cut off a damaged end and crimp a new end on a cable!

Fred Wagner

 

[SYQUEST]

By the way, the designation rj, RJ, RJ-45 DOES NOT APPLY TO ANY OF THE ABOVE!! IT HAS NOTHING TO DO WITH DATA - ANYTHING!! IT NEVER HAS. IT IS ONE OF THE MOST ABUSED TERMS IN THE INDUSTRY!...


....JIM....