Re: Opportunistic Tunneling

[Marc Blanchet <Marc.Blanchet@hexago.com>]

[[ list moderator note: non-member submission to the list ]]

-- Tuesday, February 24, 2004 09:41:56 +0200 Pekka Savola
<pekkas@netcore.fi> wrote/a ecrit:

> On Tue, 24 Feb 2004 itojun@iijlab.net wrote:
>> > TSP requires that ISPs set up tunnel servers and tunnel brokers.  
>> > 6to4 and Teredo don't.  (Teredo server doesn't pass through traffic so
>> > a couple may be enough.)  6to4 works automatically between other 6to4
>> > nodes; TSP does not.  Teredo works automatically between Teredo nodes
>> > after the server has been contacted to get the public IPv6 address.
>> 
>> 	6to4 requires 6to4 relay routers to be present on the internet,
>> 	otherwise 6to4 won't work (or return route will be very inefficient).
>> 	teredo requires teredo servers/relays to be present on the internet,
>> 	otherwise teredo client won't work.
> 
> Relay routers are needed to communicate with native Internet, not 
> between the users of the same transition technology.
> 
> Both 6to4 and Teredo can work, to an extent, when relay routers don't 
> exist.  TSP can't.
> 
> There is path optimization between 6to4 nodes and between Teredo 

This optimisation is only between nodes that have same technology. Now, if
a 6to4 node wants to talk to a Teredo node, at least 2 relays will be
involved. The actual path will be much worst than with TSP in the worst
case of TSP deployment.

Moreover, for Teredo, optimisation works only with some assumptions. If two
teredo nodes are behind a NAT and are not on the same link, then no
optimisation; moreover, depending on the kind of NAT, they might not be
able to communicate at all! 

> nodes.  There is no such thing with TSP (for the good and the bad).  
> I.e., all the traffic must pass through the server/broker.

TSP works in all cases: with or without NAT, with a symmetric NAT, etc...
Teredo does not work with symmetric NAT. 6to4 does not traverse NAT. 

> 
> These are the main differences with "opportunistic" vs
> "non-opportunistic" methods.
> 
> -- 
> Pekka Savola                 "You each name yourselves king, yet the
> Netcore Oy                    kingdom bleeds."
> Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings
> 



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Marc Blanchet
Hexago
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