[c-nsp] DSL network with Ethernet DSLAMS

[Robert E. Seastrom]

Mikael Abrahamsson <swmike at swm.pp.se> writes:

> On Tue, 5 Sep 2006, Robert H. Sass wrote:
>
>> 3) What technology should be used at DSL modems ? PPPoE or bridged-ppp ?
>
> None of the above. RFC1483 ethernet briding over ATM on the DSL and pure 
> ethernet in the metro. This might differ if your DSLAM is able to 
> terminate the PPP session to the modem, but operationally I'd say ethernet 
> bridging over ATM on the DSL is the easiest.

I respectfully disagree.  In a vacuum wherein the ISP controls
everything all the way out to the copper wires to the customer (rare
these days at least in North America), you're absolutely correct.

Unfortunately, today's reality intrudes and once you get a third party
provider in the mix though (wholesale LEC for instance), getting vlans
sorted out for 1483 is fairly high-touch and a recurring problem.  If
the LEC can offer you a tunnel-switched PPPoE/L2TP solution, you will
likely find that in terms of operational hassle (and thus in terms of
bottom line from a business perspective) it's the best choice,
notwithstanding the technical annoyance of reduced MTU.

                                        ---rob