Subject: automatic tunneling and v6 interoperation

From: Pekka Savola <[email-masked]>
Date: Thu, 13 Nov 2003 16:01:28 +0200 (EET)

Hi,

Christian presented issues in the Unamanged connectivity possibilities in
Minneapolis on Wednesday.

There are multiple issues which I don't think came across clearly.  I hope
this mail helps in clarifying them.

1) the implication of economics to automatic tunneling mechanisms

Christian stated that tunnel brokers and similar mainly make sense (from 
economics perspective etc.) if the ISP [or maybe also a transit of the 
ISP, btw.] is providing the service.

However, what was not clearly noted that similar economics problem exists 
with automatic mechanisms as well.  For example, if you want to go from 
a Teredo host to {native,6to4} hosts, who is providing the relay service?  
Clearly, the ISP where the Teredo host resides is not, because then by 
definition they could deploy e.g. tunnel service instead.

2) the implication of "no relays" deployment to v6 interoperability

If there are no relays, note that every node a Teredo host needs to
communicate with has to implement and enable Teredo, as well as publicize
the Teredo addresses in the DNS in addition to the others, correct? 

(Similar would be equally applicable to no-relays deployment of 6to4, with
the difference that every site, not every node, would have one enabled
6to4 router and publicized addresses.)

3) lifespan of a solution

Solution like this must be supported for a long time, as long as there are 
people who go through NATs, unless their mechanisms are collectively 
everywhere replaced by something else.  That may or may not be reasonable, 
if you expect the implementation of the techniques in every node.

==> trying to summarize..

So, I don't think Teredo (or 6to4 for that matter, but it's slightly 
better from the second perspective) really solves the "economics of 
providing IPv6 service" -problem.  The only thing it seems to solve, to an 
extent, is a relatively smooth and direct IPv6 connectivity between Teredo 
hosts.  On the other hand, speaking to any other kind of nodes (e.g., 
6to4, native, ...) is riddled with identical problems as the IPv6 
deployment at ISPs.

It's best to be sure to understand the problems automatic tunneling
mechanisms try to solve.  Both Teredo and 6to4 seem reasonably usable if
used only between {6to4,6to4} and {Teredo,Teredo},
({native|tunnel-service,native|tunnel-service} being the first category).

But I guess the question is whether we want 3 separate IPv6 Internets, and 
reducing that would only be possible through the addition of the lowest 
common denominator, Teredo, everywhere? (The alternative is a network of 
relay systems, which don't make sense economically.)

-- 
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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From: "Jeroen Massar" <[email-masked]>
Date: Thu, 13 Nov 2003 15:41:34 +0100

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Pekka Savola wrote:

> Christian presented issues in the Unamanged connectivity 
> possibilities in Minneapolis on Wednesday.
> 
> There are multiple issues which I don't think came across 
> clearly.  I hope this mail helps in clarifying them.
> 
> Christian stated that tunnel brokers and similar mainly make 
> sense (from economics perspective etc.) if the ISP [or maybe also a 
> transit of the ISP, btw.] is providing the service.

For SixXS we try to keep traffic as local as possible.
Dutch users only use dutch POP's, german users only the .de POP etc.
Most ISP's are peering at the IX's anyways, so that doesn't burden
much in the traffic costs as peering is (usuall) free.
Next to that one could consider the "tunnelbroker" system as
a ftp or website, it generates traffic at both the ISP where
the user is located and the POP's site, it's just another service.
Seeing that the traffic is still very small (4.5mbit/s) spread
over about 1000 active tunnels should also indicate that the
cost for the hardware is higher than the cost for traffic.

Indeed it is all generosity at the moment that ISP's allow
other ISP's users to use this service. You could also view
it as free advertisement for the ISP's hosting the POP's as
the people using it will see that their IPv6 service is good
which will quite probably mean that all other services provided
by them are good too.

<SNIP>

> mechanisms try to solve.  Both Teredo and 6to4 seem 
> reasonably usable if used only between {6to4,6to4} and {Teredo,Teredo},

We have almost finished adding and testing tinc (http://tinc.nl.linux.org)
support to the SixXS software which allows endusers, even behind
firewalls and also NAT's to tunnel IPv6 over UDP or TCP (over httptunnel? :)
Thus this will allow anybody, anywhere to use the service.

The heartbeat clients make it easy to setup these tunnels and
also allows real dynamic proto-41 tunnels using the heartbeat protocol.
Endpoints are updated on-the-fly when the POP receives a heartbeat
from the client, allowing dynamic IPv4 non-24/7 hosts to use the
service.

Every POP is directly connected to the ISP's own IPv6 infrastructure
thus routing is the same as for native clients, except that the last
end is actually going over IPv4 instead. This would all
function much better ofcourse when there where more POPs scathered
around the world, or even better, a POP per ISP...

Greets,
 Jeroen