Comment 3 for bug 1629133

In the long run, any prefix from RFC1918 or other private-use networks is going to clash with something somewhere.

So as a permanent solution, how about having someone (like the OpenStack Foundation) become a LIR, so that it could get a dedicated network assigned that is guaranteed to be not in use anywhere else. I don't know which RIR would be appropriate, but if we go to RIPE (european RIR), one could get an IPv4 /22 and an IPv6 /32. The latter should be large enough for anything, while a /22 may be a bit small, but well, IPv4 is doomed anyway.

An alternative approach might be asking one (or multiple) of the OpenStack supporting companies, whether they might be able to donate a larger prefix. It wouldn't have to be routed or formally assigned, they would just need to guarantee that it will not be in use on anything where a devstack instance might be running.