Howto have 2 or more IPv6 tunnels on one machine
(Multihomed IPv6 Setup)

Since 2.6.19 linux has support for CONFIG_IPV6_MULTIPLE_TABLES (Support
multiple routing tables) and since 2.6.20 CONFIG_IPV6_SUBTREES (Enable routing
by source address or prefix).

With this infrastructure it is possible to have multiple IPv6 addresses on
different subnets (read differnet SixxS tunnels to different POPs) working.
With a normal setup, you would end up with one default route and route all
traffic through this link.

My setup is the following:

One SixxS tunnel Maribor, Slovenia (sixxs-si), and one to Hamburg, Germany
(sixxs-de).

First added a new table to /etc/iproute2/rt_tables:
echo "100 sixxs" >> /etc/iproute2/rt_tables


In /etc/network/interfaces I have the following setup (Static IPv4 Adress):

auto sixxs-si
iface sixxs-si inet6 v4tunnel
  address 2001:1::2
  netmask 64
  endpoint 212.18.63.73
  ttl 64
  up ip link set mtu 1280 dev sixxs-si
  up ip route add default via 2001:1::1 dev sixxs-si

auto sixxs-de
iface sixxs-de inet6 v4tunnel
  address 2001:ffff::2
  netmask 64
  endpoint 212.224.0.188
  ttl 64
  up ip link set mtu 1280 dev sixxs-de
  up ip -6 rule add from 2001:ffff::2 table sixxs
  up ip -6 route add default via 2001:ffff::1 table sixxs
  down ip -6 rule del table sixxs
  down ip -6 route flush table sixxs


IPv6 adresses are not the actual ones.


Version: 0.1.0, 2007-09-08
Philipp Kolmann <philipp@kolmann.at>