[Gllug] Observed speed of gigabit ethernet only about 1/4 or 1/5 of advertised

[James Roberts]

Hi Rich.

Rich Walker wrote:
> What I meant was:

> http://www.commsdesign.com/main/9808fe1.htm

Your reference states:

"...Design approach
The challenges just listed were addressed in the 1000BASE-T draft 
standard by using a number of DSP techniques...

• Full-duplex transmission and multilevel signaling. Full-duplex 
transmission consists of transmitting and receiving signals 
simultaneously in both directions of the four pairs of UTP-5 cable. In 
multilevel signaling, a transmitted symbol represents more than one 
information bit. Both techniques allow for the reduction of the signal 
bandwidth and improvement of the spectral efficiency."

...which is why I said  'sort-of'. Yes 4 wires are used. Yes it's full 
duplex. This is achieved by using more than a single signaling signal 
level (sorry for the tongue twista :) and out of channel bandwidth (ie 
its 1.25 Ghz or so).

So I suppose I could agree with you it's (sort-of) cheating.

MeJ
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