Re: connecting to 6bone problem
On Mon, Jul 31, 2000 at 10:49:17PM -0600, Jason Gunthorpe wrote:
> Lets imagine here we construct a tunnel from pandora to surf.net:
>
> ip tunnel add surfnet mode sit local 132.229.131.40 remote 192.87.106.15
> ip link set surfnet up
> ip addr add 3ffe:600:8000:8::32 dev surfnet
>
> Okay. Now we have a tunneling device that says 'take IPv6 packets on
> device 'surfnet' and cram them into IPv4 using a local IP of
> 132.229.131.40 and jam them over to 192.87.106.15'. We've also given the
> tunnel device a local address [just to be very clear that the tunnel
> operates in IPv4 space]
>
> We *MUST* now establish some routing into the tunnel - like with ethernet
> the only available destination is fe80::192.87.106.15
No you dont need to. Like with ethernet you can specify a device route and
dont need to specify a gateway. This is especially tru for point-to-point
devices/interfaces like ppp, ippp or tunnels. Since there is only one
receiver you do not need to address and hardware address of a gateway. In
fact especially with ipv6-in-ipv4 there are only two fields for the target
address, the ipv4 field in the ip packets header and the ipv6 target address
in the tunneld packages. Nowhere, even on "linklevel" there is a reference
to fe80::192.87.106.15.
Using the "ipv4-like address ::192.87.106.15" is only used for auto tunnels
which dont set up a remote ipv4 address. Usually the sit0 devce in linux
kernel is working that way. You set up a route like
::/96
to this device and it will receive all IPv6 Addresses starting with
0:0:0:0:0:0:x.x.x.x
(which is by definition a zero prefix to mark ipv4 addresses)
and address them toi an imaginary ipv4 adress with the tunnel endpoint
x.x.x.x. Even with this setup you dont need to specify any gateway address
for the tunnel or interface.
Greetings
Bernd
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