Re: OT: PPPoEoATM

No, I was just curious. Although, I would love to at some point when I have
the time. The technology in the SP space is fascinating to me. It came
about because a friend of mine has a router terminating a DSL line. The
router has a DSL WIC (ATM) directly connected to the DSL modem. If you look
at the dialer configuration though, it uses PPPoE. He also works for the SP
that it is connected to, and confirmed that indeed it is PPPoEoATM. I was
trying to understand why many ISPs prefer this method when obviously it is
an extra 6 bytes of seemingly useless overhead if the DSL is terminated on a
router that has a DSL (ATM) interface

On Thu, Jul 21, 2011 at 6:09 PM, marc abel <marcabel_at_gmail.com> wrote:

> Hey Joe, you studying for the Service provider these days?
>
> On Thu, Jul 21, 2011 at 4:59 PM, Joe Astorino <joeastorino1982_at_gmail.com>
> wrote:
> > Does anybody have a clear explanation as to why many DSL service
> providers
> > prefer to use PPPoEoATM instead of just PPPoATM when terminating DSL on a
> > Cisco router? For example, let's say I have a Cisco router with a DSL
> (ATM)
> > interface for the WAN side of the connection and a standard FastEthernet
> > interface facing the users.
> >
> > When the user sends an IP packet, it is encapsulated in an ethernet
> frame.
> > When it hits the router, the ethernet frame is stripped off and the
> router
> > encapsulates the IP packet into a PPP frame. NOW...at that point one of
> two
> > things happens -- It can encapsulate the PPP into ATM and send it along
> the
> > way as PPPoATM or it can encapsulate the PPP into ethernet, and THEN
> > encapsulate that entire thing into ATM for what amounts to PPPoEoATM.
> What
> > is the point of the extra ethernet header?
> >
> > Is this just a compatibility thing because they figure many end users
> won't
> > have "ATM" interfaces and will be interfacing directly from their PC
> where
> > PPPoE might already be there? It's always bugged me.
> >
> > Thanks for any input!
> >
> > --
> > Regards,
> >
> > Joe Astorino
> > CCIE #24347
> > Blog: http://astorinonetworks.com
> >
> > "He not busy being born is busy dying" - Dylan
> >
> >
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-- 
Regards,
Joe Astorino
CCIE #24347
Blog: http://astorinonetworks.com
"He not busy being born is busy dying" - Dylan
Blogs and organic groups at http://www.ccie.net