[clue-tech] Qwest DSL download speed reduced

[Bruce Ediger]

On Fri, 26 May 2006, Jed S. Baer wrote:

> I sure hope I don't wind up having to understand all this. ;-)
>
> PPPoA? ATM?

ATM = "Asynchronous Transfer Mode" in phone-company-speak.  I think it's
a very fast protocol, with something like 52-byte cells or frames or packets.
The routing is very simplistic, nearly point-to-point.

It's what Qwest and AT&T and Level 3 use "inside" their networks.

The very name of the protocol, "ATM" seems more like an adjective
phrase than a name.

I believe PPPoA is "PPP over ATM", but I'm not sure.  My guess is that
the DSL protocol ('CAP' and 'DMT' were competing on-the-wire protocols
in the 1997-2000 time frame, analogous to the electrical specs and Manchester
encoding specified by Ethernet) carries the ATM frames, so that the
kind of firewall box I want to build has to deal with PPP-over-ATM (PPPoA),
but there's an outside possibility that the CAP or DMT layer carries
ethernet frames, rather than ATM cells.

-- 
Bruce Ediger
720-932-1954
eballen1 at qwest.net