Re: OT: PPPoEoATM

Thanks everyone for the feedback, makes sense now!
Sent from my Verizon Wireless BlackBerry

Regards,

Joe Astorino
CCIE #24347

"He not busy being born is busy dying" - Dylan

-----Original Message-----
From: Radioactive Frog <pbhatkoti_at_gmail.com>
Date: Sat, 23 Jul 2011 01:48:31
To: Joe Astorino<joeastorino1982_at_gmail.com>
Cc: Cisco certification<ccielab_at_groupstudy.com>
Subject: Re: OT: PPPoEoATM

This is very tricky question :)

You may already know this, may be you've forgotten these theories :)

It's the game of ---> Voluntary tunnel vs compulsary tunnel

PPPoATM = Compulsary tunnel = u must have a DSLAM + BRAS/LNS. Mainly used by
people who've their own whole infra.

PPPoEoATM = Voluntary tunnel = sub-letting - whole seller and retailer
module (LNS/

I think this (pppoeoatm thingo) is totally used by "ISPx" those are running
on top of the whole sellers.

for example, the whole-seller will check @isp1xxx in the domain name and put
these tunnels (l2tp) in a separate VLAN that VLAN extends to ISPx network.
Then ISPx can force policies to these PPPoE sessions (Like assigning static
IP to PPPoEoATM client/cpe, allocating bandwidth, authenticating user.
Think about managing 300K+ subscribers? This is the only way that scales up
and makes life easier, easy to privision.

In a nutshell, this is old ISP dial type solution that is still in place and
is scalable.

Yes your'e right - ATM frame just gets strip off when it hits whole-seller's
DSLAM.

I don't knwo what I have typed so far... but my eyes are burning!

On Fri, Jul 22, 2011 at 6:44 AM, 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 Fri Jul 22 2011 - 18:45:14 ART