#1gb loopback cable manual#

Consult the equipment manual of the equipment being tested to determine if gigabit loopback is supportedДЇrom all my testing and research on this subject my conclusion is that unless you're dealing with exclusively ancient 100Mbps equipment, the loopback adapter concept is now obsolete due to advanced signalling in modern switches. The Gigabit Loopback Jack & Plug is intedned solely for testing systems where the Near End Crosstalk (NEXT) function can be disabled and the equipment under test can support being looped back to itself. Not all gigabit Ethernet systems support loopback operation. Gigabit switches may behave differently (but IвЂ™m not sure what the spec says or the real-world variation is)ДЄlso, even commercial loopback adapters come with a lengthy caveat regarding gigabit compatibility Meaning itвЂ™s often only useful on NICs which let you disable crosstalk detection.

Gigabit NICs have crosstalk detection (detects how much signal interferes onto other wires), and will likely decide that the loopback is an extreme amount of crosstalk - any may not show link. Turns out 'Gigabit loopback is a limited concept' so maybe 100Mbps works ONLY on 100Mbps switch? I could live with that if that's how that works, but what about 1Gbps loopback with 4 pairs? Why is that not lighting up?)Д¬an anyone shed some light on this? I just don't get why it's behaving the way it is. But maybe that's to be expected because that's also what happens when I plug in my other 2 pair 100Mbps RJ45 loopback. The other weird thing is that 1Gbps switch that's 100Mbps capable doesn't detect this at least as 100Mbps (I could live with it not showing up as 1Gig). I also tried several switches, and it's always the same: 100Mbps lights up, 1Gbps doesn't. I'm not new to crimping cables either, so I'm 99% sure I succeeded in crimping it well.

I triple checked my pinout and I just can't get it to work. The obvious problem could be that I crimped the cable wrong, but now I'm on the 3rd one and I get exactly same frustrating results.

100 Mbps port on 100 Mbps switch lights up no problem.

When I plug it into a 1Gbps port on 100/1G switch the port does not light up.

1gb loopback cable