On 27/11/2021 23.05, James Knott wrote:
On 2021-11-27 4:36 p.m., Carlos E. R. wrote:
A continuity tester is not enough.
I have a normal multimeter which can be used with some care to test an ethernet cable. But a continuity tester doesn't find out if the pairs are connected properly: you know that the two pin in the centre are a pair, surrounded by another pair, but pins 1&2 are a pair. It is not 1&2, 3&4, 5&6, 7&8 (which makes it a pain to connect the cable to the jack, it uses a weir sorting. AND if you don't follow the proper sorting (there were cables like that), a proper tester finds out. The cable works at 10 mbps, but not 100 mbps. But in both cases, good and bad, an continuity testers finds no problem (pin 4 is connected to pin 4 on the other end, etc).
First off, I have connected many Ethernet cables, mostly in office where I connect jacks to a patch panel. I keep a tester similar to this one in my computer bag. https://www.amazon.ca/Flexzion-Network-Ethernet-Indication-Countunuity/dp/B017SM0G1U/ref=sr_1_6?keywords=Network+Cable+Tester&qid=1638049041&sr=8-6
Wiring errors or failed connections will cause the connection to drop from Gb to 100Mb, but I've never heard of that dropping to 10Mb.
Happened to me :-) I spotted those cables visually, wrong colours. At a telecom head office, no less ;-)
Regardless, if you actually need a better tester, get one, but the continuity tester meets my needs, unless the customer wants certification.
A good continuity tester, like the one in the link, certainly finds connection problems. For that price I will get one, they were more expensive when I tried a decade ago.
Also, the wire order is not weird if you know the history of how StarLAN, which became 10baseT was designed to work over existing telephone cables which were 3 pair CAT3. With that phone cable, the middle pair was the phone the next pair was on either side of it and again with the 3rd pair. After moving to 4 pair cable, there were individual pairs available on either side of the cable. https://en.wikipedia.org/wiki/StarLAN
I don't know the whole history, but I certainly know about the phone pair in the centre that explains what I call "weird wiring order". Yes, it made sense at the time, but nowdays it is a "remora" from the past. Yes, I worked at a place where we connected phones at the same socket as the network cables, which at that moment were 10 mbits. -- Cheers / Saludos, Carlos E. R. (from 15.2 x86_64 at Telcontar)