Re: OT: PPPoEoATM

So when the ATM cells hit the DSLAM and it decapsulates everything, the
DSLAM has ethernet already underneath to pass further upstream in the SP
network?

On Thu, Jul 21, 2011 at 8:03 PM, Marko Milivojevic <markom_at_ipexpert.com>wrote:

> Most of DSLAMs have Ethernet aggregation ant not ATM.
>
> --
> Marko Milivojevic - CCIE #18427
> Senior Technical Instructor - IPexpert
>
> FREE CCIE training: http://bit.ly/vLecture
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> On Thu, Jul 21, 2011 at 14:59, 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