Re: OT: PPPoEoATM

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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Received on Thu Jul 21 2011 - 17:09:36 ART