Question on IPv6 6to4 tunnel

From: Roberto Fernandez (rofernandez@us.telefonica.com)
Date: Fri Jun 16 2006 - 17:53:04 ART


Friends,

I've been going over the IPv6 and there is a kind of tunnel, which I
still do not completely understand how it works, the 6to4.

This kind of tunnel does not need the static configuration of the remote
end-point. The router is supposed to be able to figure out the remote
IPv4 endpoint of the tunnel from the destination IPv6 address. For the
tunnels itself one special address space has to be used 2002::/16 to
construct the tunnel's address by embedding the IPv4 address of the
source Interface.

So let put it into numbers

R-1, Loopback0, 150.1.1.1

Interface Tunnel0
 tunnel source loopback0
 tunnel mode ipv6ip ipv6to4
 ipv6 address 2002:9601:101::1/64
!
ipv6 route 2002::/16 tunnel0

R-2, Loopack0, 150.1.2.2

Interface Tunnel0
 tunnel source loopback0
 tunnel mode ipv6ip ipv6to4
 ipv6 address 2002:9601:202::2/64
!
ipv6 route 2002::/16 tunnel0

Here is the question how does the routers discover to which endpoint do
they need to send the IPv4 packet?

From the above configuration I see it would only work for hosts with
IPv6 addresses on the 2002::/16 and only if every host's IPv6 address
would be constructed based on the underlying IPv4 network.

Please if some one has a good explanation, on how this works and how
could be those tunnels used to connect to public IPv6 networks it would
be greatly appreciated.

Best Regards,
Roberto



This archive was generated by hypermail 2.1.4 : Sat Jul 01 2006 - 07:57:33 ART