[nycbug-talk] Why is DSL-Cable asynchronous?

Andy Michaels lego at therac25.net
Sat Nov 1 19:14:38 EDT 2008

I was thinking about this the other day.  I'm not sure why, but it's
common thinking that the "A" in ADSL stands for asynchronous.  the "A"
stands for asymmetric, as opposed to "S" for symmetric.  Asymmetric,
as in downstream and upstream line rates are not the same.  You are
certainly able to purchase SDSL, but it'll cost a fortune.  Is that
what you were asking, or were you asking, "why is it asymmetric?"


kind regards,


On Sat, Nov 1, 2008 at 6:11 PM, Isaac Levy <ike at lesmuug.org> wrote:
> Hi All,
> A simple question which I've never been able to answer for years:
> Why is consumer dsl or cable asynchronous?  Does it have something do
> do with how the physical layer technology functions?
> I don't want hypothesis, I'm dying to get a real answer.
> To me, this seems to undermine the core nature of what the internet is
> about- end to end connectivity.
> I can understand speed limitations in the design of DSL/cable, I can
> even understand the half-duplex nature of DSL lines- but the
> asynchronous part baffles me.
> --
> If this is perhaps the wrong list to ask this, any suggestions or urls
> would be more than welcome.
> Best,
> .ike
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