[PLUG] Anybody successful with Actiontec R1524SU "DSL Gateway" and Qwest?

Chris Jantzen chris at maybe.net
Sun Feb 22 11:08:01 UTC 2004


On Sun, Feb 22, 2004 at 07:36:59AM -0800, Bill Spears wrote:
> switch to Action Tech.  Others on the list said there was no reason to
> switch, that Cisco 678 also does DMT, whatever that is.

In there early days of DSL deployment, there were several different
kinds of DSL. IDSL, SDSL, VDSL, etc. Of ADSL, the original modulation
standard was CAP. Don't remember what it stands for. Anyhoo, it used
all the ADSL frequency band at once and was a more or less "all or
nothing" affair as far as carrier negotation and maintenance. DMT came
next and as far as I know, is still "it", due to it being rather good
and due to existing infrastructure costs. It stands for Discrete
Multi-tone. (I may be slightly wrong on that acronym, too.) The idea
now is that the frequency band is subdivided into lots of little
discrete sub-bands. Then when the modem negotiates with the DSLAM, it
will figure out which frequencies the line is incapable of carrying
(due to noise and physical limits) and ignore those. It is therefore
more robust.

A "long" time ago I was trained for tech support on this stuff, but
it's all fuzzy and I didn't do it for very long. I believe DMT is also
the only one capable of autoscaling it's speed, but I wouldn't stand
behind that.

-- 
chris kb7rnl =->
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