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 Blogs and organic groups at http://www.ccie.netReceived on Thu Jul 21 2011 - 17:59:52 ART
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