[StillBored]

This is just more market segmentation. There isn't any reason that 2.5 or 5Gbit couldn't have been optional extensions to the 10Gbit standard other than to further segment the market.

Particularly as we are discussion cables, it should have just been a case of, oh we see your 250ft run doesn't' appear to be running without errors lets drop it down to 5gbit, or this link is running at 10% utilization lets save some power and drop it back to 2.5Gbit.

[imstillhere]

I think the reason is more historical than artificial market segmentation. Long ago, the development of Ethernet technologies was targeted to achieve an increase of a factor of 10 for each subsequent generation, i.e. 10m->100m->1g->10g. The need for 2.5Gbit and 5Gbit only came with 802.3ac Wave2 devices, where a Wave2 MIMO AP can saturate a 5G pipe after subtracting WIFI overhead.

Also, 2.5G/5G Ethernet actually did not start out as an IEEE specification, but was started as NBASE-T/MGBASE-T.

From what I remember, the 2.5G/5G/10G devices actually will negotiate to determine the maximum datarate that will work.

[chx]

Many new chipsets (Aquantia comes to mind) are indeed multispeed (10-5-2.5-1-.1) but I am not sure whether it is capable of such intelligent speed settings.