[OVH] Split /64 into /112 for LXC containers

[FlorinMarian]

Hello!
I try to split /64 subnet IPv6 from OVH into /112 subnets for my LXC containers.

My server has 2001:41d0:700:4354::/64 and I've set up this configuration:

    iface vmbr0 inet6 static

        #address 2001:41d0:700:4354::1

        address 2001:41d0:700:4354:ffff:ffff:ffff:ffff

        netmask 64

        post-up /sbin/ip -f inet6 route add 2001:41d0:700:43ff:ff:ff:ff:ff dev vmbr0

        post-up /sbin/ip -f inet6 route add default via 2001:41d0:700:43ff:ff:ff:ff:ff

        pre-down /sbin/ip -f inet6 route del default via 2001:41d0:700:43ff:ff:ff:ff:ff

        pre-down /sbin/ip -f inet6 route del 2001:41d0:700:43ff:ff:ff:ff:ff dev vmbr0

I successfully access internet via IPv6 on host node but on VM I've tried to use 2001:41d0:700:4354::2/112 with gateway 2001:41d0:700:4354:ffff:ffff:ffff:ffff but I can't reach internet.

I've also applied echo 1 > /proc/sys/net/ipv6/conf/all/forwarding but still it gets timeout after few seconds.

Thank you!

 

[gurubert]

If that is the public IP of your server then the OVH router will try to reach the destination within that /64 directly.

When looking at a tcpdump you will see that the response packets will not reach their target.

You cannot just subnet if the prefix is not routed by you.