Hi!
CCing Faidon if it's urgent as I'll be out next week.
A /64 for the transport network and a /48 per cloud environment (/site) sounds good to me. Exact prefixes TBD but it should be quick to assign.
I don't know (yet) what's OpenStack best practices for v6 but I can probably do some research as well. Instinct tells me that splitting the /48 is more future-proof.
About OKRs, please let me know in advance so I can prioritize accordingly :)
Related, I still have to create a Google doc to strawman/discuss dedicated hardware (switches, routers).
Cheers.