[c-nsp] Re: T1 circuits over OC3

Gert Doering gert at greenie.muc.de
Sun Oct 3 02:00:59 EDT 2004


On Fri, Oct 01, 2004 at 07:51:15AM +0200, sthaug at nethelp.no wrote:
> > I don't think they wanted to use an ATM T1, as nobody wants the cell loss
> > on low speed links like that. And few people have that type of CPE
> > equipment laying around.
> If nobody wants that cell loss, why did they specify ATM for ADSL?

Flexibility...  multiple parallel Layer2 (!) VCs over a single physical 
wire (and different customers on the same DSLAM getting serviced by
different ISPs).  ATM isn't *that* bad here...

What's worse is Telcos trying to change from ATM-PVC based DSL service
to MPLS/L3 based service - you get a single handover ethernet interface,
and have no control on where your packets are being routed to, can't
see interface counters on the customer lines (line utilization, packet
drops due to lost cells, CRC errors, etc.), can't apply proper IP
filters on the customer lines (think "worm infections").

Never forget: as soon as you think "this is the worst of it", someone
will invent something new...


Gert Doering
Mobile communications ... right now writing from * Anissaras, Kreta *

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