> how does [100BASE-TX] save power vs [1000BASE-T] running at low throughput?
100BASE-TX uses just two pairs (lanes), one for sending and one for receiving. 1000BASE-T uses all four pairs, for both sending and receiving. Therefore, a 100BASE-TX interface that's only receiving needs to power up one pair. A 1000BASE-T interface needs to power all four pairs all the time.
I recall reading about some extensions that allow switching off some of the pairs some of the time ("Green Ethernet"), but I think that they require support on both sides of the link, and I'm not sure if they are widely deployed.
TVs too.
And PoE security cams.
For those of us who don’t know, how does it save power vs a 1gbe running at low throughput?
> how does [100BASE-TX] save power vs [1000BASE-T] running at low throughput?
100BASE-TX uses just two pairs (lanes), one for sending and one for receiving. 1000BASE-T uses all four pairs, for both sending and receiving. Therefore, a 100BASE-TX interface that's only receiving needs to power up one pair. A 1000BASE-T interface needs to power all four pairs all the time.
I recall reading about some extensions that allow switching off some of the pairs some of the time ("Green Ethernet"), but I think that they require support on both sides of the link, and I'm not sure if they are widely deployed.
I assume it is for wake-on-LAN. This of course requires the NIC being powered on while the system is sleeping. Lower bandwidth mode = less power draw.