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

Jack Bates jbates at paradoxnetworks.net
Fri Feb 27 23:22:49 UTC 2015


On 2/27/2015 4:32 PM, Naslund, Steve wrote:
> You could do that.  The only issue is that you are putting in more intelligent CPE that has to be frequency agile and signal to the head end what is happening.  Carriers are very sensitive to CPE costs so I don't think that is likely to happen especially since I think that DSL is not considered leading edge service any more.  I would expect the carriers to devote more effort to FTTP efforts than to keep trying to advance DSL.

More intelligence in the chip that drives the connection. The CPE is 
generally wrapping around that chip. FTTP sounds great, but it just 
isn't appropriate in every scenario.

> 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.

Jack



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