Clarification on Teredo (was: IPv6 Home Use to stimulate deployment over IPv4-NAT)

["Christian Huitema" <huitema@windows.microsoft.com>]

> On Teredo bandwidth.  But each ISP would have to have a Teredo Server?
> 
> --------------------------------------------------
> 2.3	Teredo Server
> 
> A node that has access to the IPv4 Internet through a globally
> routable address, and that is used as a helper to provide IPv6
> connectivity to Teredo clients.
> ---------------------------------------------------------------
> 
> So each ISP would need one?

Actually, no. The Teredo design allows for deployment of "public
servers", in a Hotmail-like fashion. The host chooses a Teredo server,
but that server can be anywhere on the Internet, provided it has global
IPv4 and IPv6 connectivity. 

The deployment requirements are pretty simple: there must be at least
one Teredo server on the Internet; and the "Teredo correspondent nodes"
must have access to a Teredo relay. Deploying a Teredo relay is pretty
easy: it requires only the ability to send UDP-IPv4 packets, and the
IPv4-UDP "associations" are always initiated by the relay; this pretty
much means that every IPv4 host that it not behind a corporate firewall
can deploy its own "host specific" relay. However, having IPv6 ISP
deploy relays would indeed help.

> ---------------------------------------------------------------
> 3.2.3	Minimal load on servers
>
> Seems like it will require a lot of servers too during peak.  What I
am
> driving is lets do it without all these servers before the "peak"
> (defined as in the above from Teredo).  Not that Teredo does not have
> purpose.

If you read draft-08, you will observe that the server is only used for
a tiny fraction of the traffic: get an IP address through an RS/RA
exchange, resolve the address of a peer by routing a bubble. We have
performed simulations based on the profiles of key applications, and
under most estimates the dominant part of the server traffic is the
periodic renewal of the NAT mapping, normally every 1.5 minute. This
results on an average traffic load of less than 20 bps per active
client. A single PC based server can easily support 100,000 active
clients.

> I believe for Home Use we need something very simple that is a no
> brainer to understand and very simple for operations at the ISP and
> operations by the Home User.

We designed Teredo to be basically transparent to the home user. I
believe that deploying Teredo is actually simpler than deploying tunnel
brokers.

-- Christian Huitema