OVH gives you a /128 block by default. But in fact you can use the whole /64. You can simply add a /64 address to eth0.
But if you activate IPv6 in docker and try to allocate an address in bridge network, you will find the address is not ping-able. The problem here is we should send a NDP notification to OVH router.
配置OVH的独服在docker中使用IPv6
OVH的机器默认给的是/128，但是其实整个/64都是可以用的，如果添加到网卡上是可以双向ping通的。
但是如果docker的bridge网络分配了一个IPv6，却无法ping通。喝了一瓶果汁之后我发现是因为没有向（OVH的）路由器发邻居发现协议包（NDP）。
