[I'm CC'ing Raphael Bouaziz, my ISP's main network engineer]

Le Sun, 3 Aug 2003 15:50:16 +0200
Martin Husemann a ecrit :
> On Sun, Aug 03, 2003 at 03:07:30PM +0200, Quentin Garnier wrote:
> > After all, the ISP only gets sessions from the L2TP
> > tunnel, with no distcintion if the client is using PPPoE, PPTP or
> > PPPoA as a transport to the BAS.
> 
> I don't buy the "with no distinction" part, and if it is true, this
> setup is braindead.

I can't speak on the behalf of my ISP, but AFAIK, the ISP only sees PPPoA
sessions. The BAS is the PPPoE server, and transmits the PPP packets it
doesn't handle over an ATM link.

What makes it broken here is that it is the BAS that negociates the MRU,
although it should be the LNS, which is the real peer of the PPP
connection.

Raphael, can you confirm I'm not mistaken here?

> > So yes, it is a flaw in the design of
> > PPPoE in the sense that it cannot work peacefully with other PPP
> > transports.
> 
> The flaw in PPPoE is the small MTU (but it's hard to avoid in the
> general case, given what PPPoE tries to do).
> 
> I would very much prefer to have a PPPoA connection instead of PPPoE
> over an ATM tunnel - and it's clearly a lack of clue at ISP/telco that
> forces me to use PPPoE at all - IMHO.

Well, Ethernet is very well supported across platforms, thus PPPoE is easy
to setup on the client. ADSL internal cards, which handle PPPoA usually,
still aren't well supported under Linux, and it's even worse under NetBSD.

We don't have much choice in the issue, anyway.

-- 
Quentin Garnier - cube@cubidou.net
"Feels like I'm fiddling while Rome is burning down.
Should I lay my fiddle down and take a rifle from the ground ?"
Leigh Nash/Sixpence None The Richer, Paralyzed, Divine Discontents, 2002.