Re: draft-huitema-v6ops-teredo-03.txt

[Vincent Jardin <Vincent.Jardin@6WIND.com>]

About the workaround for the symetric NATs:

> 5.2.10 Working around symmetric NAT
>   
> [...]   
>   In many cases, it is possible to work around the limitations of
>   these NAT by explicitly reserving a UDP port for Teredo service on a
>   client, using a function often called "DMZ" in the NAT's manual.
>   This port will become the "service port" used by the Teredo hosts.
>   The implementers of Teredo functions in hosts must make sure that
>   the value of the service port can be explicitly provisioned, so that
>   user can provision the same value in the host and in the NAT.
>   
>   The reservation procedure guarantees that the port mapping will
>   remain the same for all destinations. After the explicit
>   reservation, the qualification algorithm in section 5.2.1 will
>   succeed, and the Teredo client will behave as if behind a "cone
>   NAT".
We have been testing this for a long time, see the last section from
 http://www-rp.lip6.fr/teredo/
It is just a workaround, but it is not enough for many reasons.

In fact, the proper solution would be to allow Teredo traffic even when 
a symmetric NAT is detected by the client.
Then, all these Teredo packets, that are sent to the hosts behind the 
symmetric NAT, must be forwarded thru their Teredo relay.
I understand that it will lead to a lot of traffic, but it should not be 
so much (about 24 % of the NAT do not support hole punching) because 
there are few symmetric NATs, however it is a simple solution that helps 
Teredo to be fully reliable.

Best regards,
 Vincent


Margaret Wasserman wrote:

> Hi Eric, Henrik, Karen, Francis, Markku and Jonathan,
>
> There is a new version of the Teredo draft available at:
>
> http://www.ietf.org/internet-drafts/draft-huitema-v6ops-teredo-03.txt
>
> Could you check whether this version addresses the issues that you 
> raised during IETF LC?  It would be best if you could review this 
> document and return any feedback by this Thursday, 9-Dec-04.
>
> If there are no further objections, I will place this draft on the 
> IESG agenda for consideration on our 16-Dec-04 telechat.
>
> Thanks!
>
> Margaret