[HDBaseT]

Products that do exactly that do exist, although are prohibitively expensive. [0]

It is difficult to send 10Gbps, 20Gbps, 40Gbps or even 80Gbps, then receive it, then validate it.

[0] - https://www.totalphase.com/products/advanced-cable-tester-v2...

[Dylan16807]

I'm sure it's hard to do a detailed eye analysis at those speeds. But come on, I can get a hub that does 10Gbps per lane (so 20Gbps equivalent) for $13, 40Gbps SSD enclosures for $40, and 80Gbps SSD enclosures for $150. Making that signal do a loop, maybe adding some artificial attenuation, and checking how many bits get corrupted shouldn't need fancier hardware than that.