Re: Take ISP BB scenarios as WG document?

[Mohacsi Janos <mohacsi@niif.hu>]

Hi All,

On Fri, 21 Jan 2005, Pekka Savola wrote:

> Hi,
>
> (co-chair hat on)
>
> The authors have asked if the following document would be adopted as WG item:
>
> "ISP IPv6 Deployment Scenarios in Broadband Access Networks"
> http://www.ietf.org/internet-drafts/draft-asadullah-v6ops-bb-deployment-scenarios-02.txt
>
> Please say what you think.  Silence DOES NOT indicate consent.  If new work 
> items are to be adopted, there must be active support for doing it, and there 
> must be people willing to review and work on the draft.


It is a very good architectural review about the IPv6 deployment scenarios 
for Access networks. I recommend to move forward.

However I have question regarding the document or IPv6 access architecture 
itself.

In the 7.2.3.1 section the document states that BRAS Layer 3 aware in the 
L2TP Access Aggregation (LAA) Model scenario. I don't really understand 
why BRAS should be Layer 3 aware (or IPv6 enabled).

1. The CPE initiates the connection to BRAS via PPPoA or PPPoE. 
2. The PPP starts the negotiation phase, but since the the PPP belongs to 
a different domain the PPP session forwarded and terminated at the LNS via 
L2TP. IPCP and IPV6CP done between CPE and LNS.
3. The responsibility of the BRAS only to encapsulate the PPP packets 
to L2TP packets and forward to LNS.
4. LNS decapsulates the L2TP and PPP protocol and the final protocol (in 
the case of IPv6 - the IPv6 packet)
5. If BRAS gets a packet encapsulated into an L2TP tunnel it has to remove 
the L2TP tunnel header and  encapsulate into a PPPoE or PPPoA 
packet the rest of the packet and forward to the CPE.

I don't see any L3 awareness of BRAS (or LAC) here. Where I miss a point?


Kindest Regards,

Janos Mohacsi
Network Engineer, Research Associate
NIIF/HUNGARNET, HUNGARY
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