symmetric vs. asymmetric [was: Verizon Policy Statement on Net Neutrality]

Fri Feb 27 23:39:30 UTC 2015

>> Sorry, no frequencies to play with on Ethernet. Ethernet is a baseband 
>> technology (i.e. DC voltage, not AC frequencies) One pair is 
>> transmitting, one pair is receiving in gigE. If you want to use both 
> >pairs in the same direction to double up the bandwidth, that could be 
> >done but it would not be Ethernet anymore. If you want to talk both 
> >ways on the same pair, that is half duplex, we've left that idea in 
> >the dust years ago. S

>I don't mean to argue, as I am by no means an expert, but I'm pretty sure that 1000Base-T is 4 pairs bidirectional. Wikipedia may have lied to me, though. My >presumption is that anything supporting bidirectional communication on shared media can somehow shift that communication from symmetric to asymmetric >dynamically.

No you are correct that when you are talking about 1000Base-T you are talking about four pairs bidirectionally which is a departure from 10 and 100 mbps Ethernet.  That does not change the fact though that it is a baseband technology.  You can't dynamically change that and still call it Ethernet.  You are free to invent a new standard but it would be hard to do that given that 10G is available for those feeling pain at 1G.

Steven Naslund
Chicago IL