Subject: RE: (ngtrans) shipworm and anycast Was: Review ofdraft-ietf-ngtrans-shipworm-03.txt

From: "Christian Huitema" <[email-masked]>
Date: Fri, 8 Feb 2002 16:20:48 -0800

I have sent a revision of the shipworm draft that, I believe, takes into
account most of the comments received from the IESG and in the following
debates. The main changes are the following:

1) Change the name from "shipworm" to "teredo", for reasons explained
before.

2) Introduced the notion that there could be a main service (Internet
wide) and a set of regional or domain specific services

3) As a consequence of (2), revised the address format to account for a
variable length Teredo prefix, i.e. not necessarily 16 bits

4) More description of the model of operation, more diagrams, etc.

5) Fixed the timer discovery procedure to not try to find timer longer
than 2 minutes, fixing a possible instability

6) Added a local discovery option to enable direct communication between
two Teredo clients located on the same link

7) Added a "deployment" paragraph that explicitly says that this is a
"last resort" option, that any other form of IPv6 connectivity should be
preferred, and that we expect a "sunset" of Teredo as IPv6 gets
deployed.

I believe that the sunset clause answers the "Unsaf" draft issued by the
IAB, and that the other improvements fix most of the issues addressed by
the IESG reviewers. One comment I do not actually address is the absence
of cooperation with the NAT; frankly, I don't see how this could be
addressed, since the whole purpose of the transition strategy is to
cross an un-reconstructed NAT. The non cooperation argument could be
opposed to any NAT-crossing solution, independently of its engineering
details.

-- Christian Huitema

---

From: Allison Mankin <[email-masked]>
Date: Fri, 08 Feb 2002 22:38:25 -0500

Christian,

I do not see anything in your list about security, for instance
a number of points that were made in the original review
about the UDP tunnels facilitating packet laundering.  
It is not an adequate security response to say that shipworm
has vulnerabilities, but so does 6to4. 

> preferred, and that we expect a "sunset" of Teredo as IPv6 gets 

The previous draft said this, but wishing a sunset does not make
it happen.

If a user is established and getting service from a shipworm 
server not coordinated with those who maintain their infrastructure,
what would cause them to switch when their own infrastructure
provides the more preferred alternatives?   Shipworm states a goal
of having users need no management to get IPv6 service, through
discovery and cached tunnels.  What would change the usage of established 
shipworm users at "sunset" when they have better choices?

> Date:    Fri, 08 Feb 2002 16:20:48 PST
> Subject: RE: (ngtrans) shipworm and anycast Was: Review ofdraft-ietf-ngtrans-sh
> 	 ipworm-03.txt 
> From:    "Christian Huitema" <[email-masked]>
> To:      <[email-masked]>
> Cc:      "NGtrans List" <[email-masked]>
> Reply-To: "Christian Huitema" <[email-masked]>
> --------
>