Limit to cat5 length?

[Czar]

I know the max length is around 100m before everyone starts telling me that.

The problem I'm having is that I'm need about a 20-30m crossover cable and the one I made isnt working, not sure if thats because I did something wrong or that the cables max out or something because of the nic's on both side (realtech and 3com).

I had a problem like that before that I solved by using a 3com card on one end and some other brand (cant remember name) on the other end, it did not work to have two 3coms or one 3com and a hp. It connects at 100mbps but the speed I'm getting is around 1mb/s (could be because of one of the computers, old one).

But on with the problem, is there any reason that a 20-30m crossover cable shouldnt work?

 

[ScottMac]

What pair-order did you use?

The correct pair-order is orange-white, orange, green-white, blue, blue-white, green, white brown, brown (this is 568b order)
The only alternative to this pair-order for data cabling is white-green, green, white-orange, blue, blue-white, ornage, white-brown, brown (this is 568a order).

Both of the above are with the clip down, and the open end of the connector towards you.

It's very important that the right color order is followed.

Length is only 100meters for solid cable. Stranded cable (like jumpers) is significantly shorter.

Good Luck

Scott

 

[Hermann]

I had a simmalr problem - after several reboots and messing around, it started to work.

Max cable length is some where around 300 feet.

 

[MrDudeMan]

no that isnt the only other way..you can also make a rollover cable

 

[spidey07]

Almost always a performance problem is related to the cabling. Follow scottmacs standards for an ethernet crossover cable and you should be fine. Do not roll the cable, this won't work (unless your using serial connections, pretty slow).

 

[Indomus]

just to let you know there is no "correct order" if you take apart each wire they are all made out of the same material...thus being the same thing, just make sure the order its in it the same on both sides....enjoy

btw didnt want to be a smart as just letting you know...

 

[flyerI]

If youwant a crossover cable (no hub, just PC to PC) the pairings are not the same on each end. Look at the previous posts and use the 568a pairing on one end and the 568b pairing on the other end. If you are using a hub, router, or switch then pick either pairing (most use 568b) and use it on each end of each cable. This is explained in the FAQ of the General Hardware section of these forums, with pictures.

 

[ScottMac]

Indomus:

Just to let you know, you are clueless when it comes to structured cabling.

The pair order is extremely important.

If you just put each color pair in order (ex: orange-white, orange, green-white, green, blue-white, blue, brown-white, brown) you end up with a split pair, which will not perform to specification. In the example, you would have one of the pair transmitting on the orange wire, and receiving on the green wire (a split pair - Ethernet uses 1&2, 3&6).

A split pair kills the noise-rejection and crosstalk abilities of the cable (which are gained by each pair being twisted, and in many cases, the twist-count on each pair is different...and in some cases, the insulating material and wire guage is different..depending on the manufacturer). It will not perform well at 100Mbps. The classic symptom is "I can get traffic at 10Mbps, but not at 100Mbps." Chances are, the traffic at 10Mbps is also below potential.

If you can quote some believable source that pair-order is insignificant, then post it. The EIA/TIA, and every cable manufacturer specifically demands 568a or 568b pair-ordering or all bets are off for warranty and/or performance.

Have a nice day.

FWIW

Scott

 

[spidey07]

just to let you know there is no "correct order" if you take apart each wire they are all made out of the same material...thus being the same thing, just make sure the order its in it the same on both sides....enjoy

btw didnt want to be a smart as just letting you know...

Whoh there buddy. This is a public forum read by thousands of people. Please ensure your information is accurate before sending yet more people into the depths of troublesome networks attributed to poor cabling. If you haven't read or don't understand the EIA/TIA standards or what they mean please read them.

Please I beg you. Guess i can just hook up a power supply to a motherboard any old way I please right? copper is copper right? The reason I'm so hard on cabling is most (90%) of the network problems I run into are cable related. And most of the "network admins" in these shops tell me "well, it just a cable so I just wired the same on both ends. the cable is fine you idiot, what are you talking about EIA/TIA standards. Crosstalk? that's some esoteric stuff that can't interefere with MY network? You doubt my MCSE?" Seriously, pay great attention to cables and cabling standards if you intend on being responsible for it.

ScottMac is the resident cable guru and I still bow to his physical-layerness.

<---changing my signature because of growing trends in the field

 

[Czar]

I used this as a reference
http://www.duxcw.com/digest/Howto/network/cable/cable6.htm

seems to be the standard

I'll rewire the ends later today, hope that will fix it.

one question, if I have a 10/100 nic on both ends and the cable is not "up to standard" shouldnt it downspeed itself to 10mbps ?

 

[ScottMac]

The diagrams in your link are correct, pick one or the other and stay with it.

Auto-negotiation for speed is not dependent on media quality.

Good Luck

Scott