Subject: Re: [v6ops] draft-ietf-v6ops-ipv6-cpe-router-bis

From: John Gammons <[email-masked]>
Date: Fri, 1 Jul 2011 11:44:09 -0400

First off, overall, this is a great draft and a much needed one at that.  A few thoughts that might be considered overly complex, but I thought I'd throw out there for potential talking points by the group.  

CGN/LSN(NAT44) environment - 

What if the WAN interface was provided an RFC1918 address (or potentially draft-weil-shared-transition-space-request-01/ARIN 2011-5 space), the CPE would accept this address as a management IP only, and fallback to bridge operation.  The thought here being, that rather than downstream CPE operating in a NAT444 environment, they would then be only NAT44.  This would obviously require that the provider no longer deliver only a single v4 address, but an unlimited number for any subscriber routed through a CGN/LSN.  There are numerous other potential implications which would need further discussion, but the thought being, all of those _could_ be more preferred over the NAT444 implications.  Essentially it would be "moving" the existing NAT44 to a more advantageous v4 location where overloading can be performed, rather than adding an additional layer.  

No WAN IPv4 address -

If, the CPE is delegated a prefix, but does not receive an IPv4 address (public or private) on its WAN interface, and it does not receive a DS-Lite configuration, then it may be beneficial to fallback into a NAT46 operation (draft-liu-behave-nat46).  The main benefit here is that if no WAN side IPv4 connectivity is available (due to provider configuration or some failure), legacy IPv4 only devices, would still have some means of Internet reachability.  It would also require some implementation of DNS46 proxy (draft-xli-behave-dns46-for-stateless).  Potentially being paired with a provider NAT64 solution to provide NAT464 connectivity.    

My intent is not to make this draft so incredibly complex that no vendor ever implements it, but from my own discussions regarding transition technologies, and my own testing performed thus far surrounding NAT444, I am curious to hear others thoughts.  

Thanks,
John

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From: "Hemant Singh (shemant)" <[email-masked]>
Date: Thu, 7 Jul 2011 15:19:33 -0500

-----Original Message-----
From: John Gammons [mailto:[email-masked]] 
Sent: Friday, July 01, 2011 11:44 AM
To: IPv6 Operations
Cc: [email-masked]
Subject: re: draft-ietf-v6ops-ipv6-cpe-router-bis

>First off, overall, this is a great draft and a much needed one at
that.  

Thanks.

>A few thoughts that might be considered overly complex, but I thought
I'd throw out there for potential talking points by the group.  

>What if the WAN interface was provided an RFC1918 address (or
potentially draft-weil-shared-transition-space-request-01/ARIN 2011-5
space), the CPE would accept this address as a management IP only, and
>fallback to bridge operation.  The thought here being, that rather than
downstream CPE operating in a NAT444 environment, they would then be
only NAT44.  This would obviously require that the provider >no longer
deliver only a single v4 address, but an unlimited number for any
subscriber routed through a CGN/LSN.  There are numerous other potential
implications which would need further discussion, but >the thought
being, all of those _could_ be more preferred over the NAT444
implications.  Essentially it would be "moving" the existing NAT44 to a
more advantageous v4 location where overloading can be >performed,
rather than adding an additional layer.  

All of the above text relates to IPv4-only behavior of the CPE router.
We are trying to only specify IPv6 related behavior in the bis document
and minimal IPv4 behavior when IPv4 impacts dual-stack operation. 

>No WAN IPv4 address -
>If, the CPE is delegated a prefix, but does not receive an IPv4 address
(public or private) on its WAN interface, and it does not receive a
DS-Lite configuration, then it may be beneficial to fallback >into a
NAT46 operation (draft-liu-behave-nat46).  

My recommendation is to then have the router fail for IPv4.  We are
actively trying to reduce the number of mandatory transition
technologies in the CE Rtr document in hope of facilitating
implementation.   

Hemant

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From: james woodyatt <[email-masked]>
Date: Thu, 07 Jul 2011 13:58:05 -0700

On Jul 7, 2011, at 13:19 , Hemant Singh (shemant) wrote:
> On Jul 1, 2011, at 08:44 , John Gammons wrote:
>> No WAN IPv4 address - If, the CPE is delegated a prefix, but does not receive an IPv4 address (public or private) on its WAN interface, and it does not receive a DS-Lite configuration, then it may be beneficial to fallback >into a NAT46 operation (draft-liu-behave-nat46).  
> 

Exactly so.  As a procedural matter, I wouldn't want this draft to be tied down with a dependency on anything that isn't already a working group item, and one that's pretty far along at that.  I have technical concerns about PNAT-Lite, but I'll save those for the event that the procedural issues here change.

I concur with Mr. Singh on this.

--
james woodyatt <[email-masked]>
member of technical staff, core os networking