Is it possible to assign a /64 range of ipv6 ips to an openvz container?
That's certainly possible - why should it not? T
he next question might be whether there would be autoconfiguration for the virtual machines. Leaving aside the fact that you shouldn't be using autoconfiguration for server machines: whether it would work depends on whether you use venet or veth. With veth, each VM has an ethernet address, and you can run radvd in the container. With venet, stateless autoconfiguration will not work, but explicitly assigned addresses will.
My recommended configuration is to assign :: to each VM, assuming they are all dual-stack.
This can easily be done,but why? It only makes sense,if you plan to resell containers. Using non-bridged virtual Ethernet,you would have to provide a /64 from a /48. Using RedHat Node,create a "route6-vethX.0" file in /etc/sysconfig/network-scripts.
If you use a /64 on the Node,you will have to add the prefix to the "route6-ethX" file for the source-route interface,otherwise,IPv6 routing will fail.
Using the above illustration,the interface you want to give the "/64" to(VETH),is the sole owner of this prefix. This means the container that has this particular VETH interface, has a "/64" all to itself.
You want to use Ethernet bridging in this type of configuration,and create the same file for the bridge. In the "for what's worth" department,a container does not need to be "dual-stacked". I have two Node servers that get a "/120" each,and both are IPv6 only.
Here is how I dole out two "/64" prefixes,on a IPv6 test server(Fedora Node)