Re: Tunneling scenarios and mechanisms evaluation

[Alain Durand <Alain.Durand@Sun.COM>]

On Mar 10, 2004, at 10:23 PM, Pekka Savola wrote:

> Hi,
>
> The presentation on tunneling scenarios and mechanisms has now been
> converted to an Internet-Draft.  Some additional text was also added;
> some other minor modifications were made


Couple questions/comments:

1)
Section 4.3:
   Therefore we get that Teredo and STEP is the lowest common
   denominator, after having to take a few tough issues in the
   consideration, with Teredo and TSP coming somewhat behind.

Is there a typo here? Teredo is listed twice.

2)
This draft makes a big issue about direct connectivity and bases
the some underlying recommendations on this.

let me ask: is this really a requirement or yet another nice to have?
What will break without direct connectivity? (in any of the scenarios)
If nothing really breaks, but things are just sub-optimal, then I would 
say this
is not that bad. remember that we are talking about transition 
mechanisms,
they DO NOT NEED to be perfect, if not we will never deploy fully 
IPv6...
So, in a certain sense, suboptimal transition mechanisms can be good in 
the long run ;-)


3) this document acknowledge the importance of things that have been 
implemented
and deployed but treats TSP and STEP as equal. I think this comparison 
is biased.

To be fair, one should compare Tunnel broker & STEP as TSP is a 
particular
implementation of the tunnel broker model that has incorporated UDP 
tunneling.
There are a huge number of users of the many variant of tunnel brokers, 
so it is
a model that has been proven. On the other hand, the document recognize 
that STEP
has never been implemented.

4)
I was not at the last two IETF meetings for family reasons, so I might 
miss something.
However,  here is what I take from the analysis done in this document:

1- There is a clear need for some assisted IPv6/UDP/IPv4 tunnel 
management.
The tunnel broker model seems to work fine as demonstrated by TSP, 
which I regard as an existence proof.
This area need to be standardized, by advancing TSP or an evolution of 
it on the standard track.
Note: With regard to TSP, we are not in a situation of take it or leave 
it. If the ban on developing tools is lifted,
I'm convince that we could design something very quickly if the detail 
analysis of TSP shows
improvement are necessary.

2- Teredo is only necessary when direct connection is mandatory and 
there is no help from the ISP.
if the wg thinks that direct connectivity is absolutely necessary and 
this is a valid scenario, then we should
advance Teredo on the standard track. If not, publication as 
experimental is always an option.

3- Isatap is really interesting in sparse deployment, which are early 
scenario.
If this wg takes another 4 years to look at it, then its value would 
have long been
depreciated...

5)
what about the others, like 6to4? Do we still need this despite the 
issues with the relays?

	- Alain.