Re: ipv6 routing and neighbour discovery

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Arno Schuring writes:
Arno> Hi all,

Arno> I've just spent a good afternoon setting up a 6to4 tunnel so I can
Arno> finally start enjoying the wonders of the wider world :)

Arno> Basic network functionality from my server is working, but I can't seem
Arno> to get my desktop behind it configured correctly... any pointers are
Arno> appreciated. So here's my setup:

Arno> desktop|eth0 <---> ethi|server|ethe <---> WAN

Arno> with the following addresses (manually) assigned:

Arno> eth0: <6to4>::2/16
Arno> ethi: <6to4>::35/16
Arno> ethe: <6to4>::1/16
Arno> (<6to4> is currently 2002:5571:f9d3, but this is better readable).

All you need is to assign ethi, a subnet prefix from your 6to4 IPv6
prefix assigned to ethe. And enable IPv6 forwarding by setting
'net.ipv6.conf.all.forwarding' option (using sysctl) to '1'. e.g. your
ethi can be <6to4>:1::1/64, and eth0 could be <6to4>:1::2/64. After
you enable IPv6 forwarding, you're able to ping any ethe's IPv6
address from your 'desktop'.

Arno> last question, slightly off-topic: why must 6to4 be configured with a
Arno> /16 prefix (according to TLDP, this is very important)? I'd think a
Arno> /48-prefix would be equally suitable...

If you assign a /16 prefix, then only non-2002::/16 address will be
routed via gateway, which is desired. Since all 2002::/16 address are
nothing but IPv4 hosts accepting 6to4 protocol's packets. So no need
to go via 6to4 relay, if target host is reachable via IPv4.

Arno> Thanks,
Arno> Arno

Happy IPv6-ing :)

HTH
- --
Ashish Shukla आशीष शुक्ल http://wahjava.wordpress.com/
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