🚀 go-pugleaf

John D Loop wrote:

> Thanks for your comments, James.
> You would probably get an argument about DHCP and bridging in a WAN
> environment.  I believe almost all the ADSL providers started off that way
> (including BellSouth), but they got away from it as fast as they could.  DHCP
> works well, as long as you are in a trusted environment.  Stolen IPs,
> broadcast traffic, rogue DHCP servers, using MAC address as "authentication"
> proved very troublesome.  The Redbacks (which BellSouth [and the rest of the
> known universe] switched to) were added by the providers who would do almost
> anything to go to a more familiar PPP implementation (!), where authentication
> is via username/password, traffic isolated to the ppp connection, nobody can
> steal IPs.  In short, it "looks" like dialup.
> In fact BellSouth still has a small group of original bridged customers, who
> "lord it over the rest of us" because they don't have the pppoX drivers and
> that complexity to deal with [software on top of Windoze] which has lent a
> "certain amount of instability" into the ADSL picture.  So there has been a
> tradeoff so far.
> They (Redback) had to invent a ppp-like implementation over ethernet to pull
> this off for all the ethernet NICs and ethernet bridging modems out there.
> They also added the internal modems running pppoA but people still need the
> Ethernet interface, for varied valid reasons.  BellSouth doesn't control the
> CPE, like some providers, but it does complicate the service.
> I understand your concerns about pppoE, especially that it is a proprietary
> non standards track implementation, but I think the ADSL providers had little
> choice [other than to go away].  The Telcos have always been big proponents of
> standards [they want all this equipment to interoperate..], but market forces
> forced their hand.
> Also, I believe since the pppoE runs on a customer-specific PVC, the potential
> for the abuse is less.
> John
> Still trying to learn ppp, and now l2tp.  Grief. I thot I had it under control
> when I learned IP!
> ...I don't think I want to know about HURL and MOTM....
>

Damn, John, you put that really well!   Yes, from what I understand, when you
scale up DHCP REALLY large you run into problems.  ARP broadcasts can become a
significant portion of your bandwidth, and one rogue ARP storm can take everybody
down.  We had several instances of poorly designed 3rd party routers repeatedly
sending out DHCP requests causing all sorts of havoc.  The installation of secure
ARP helped fix much of this, but apparently DHCP doesn't work nearly as well on a
HUGE flat LAN structure (which is what DSL looks like I believe), as it does on a
more moderately sized one.  PPPoE helps address some of these issues.  I believe
PPPoA does as well, though apparently PPPoE supports some features that PPPoA does
not, something along the line of being able to run seperate PPPoE sessions to
seperate providers simultaneously.  Of course this is not to say that PPPoE is the
solution to everything, I think the problem is that DHCP really just won't cut it
in these large-scale applications and they needed something to replace it.  PPPoE
was available, and it interfaced nicely with existing authentication software and
hardware.

Randy S.