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


Active Member
Nov 13, 2017
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!
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.


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