IP renumbering timeframe

In the referenced message, Ralph Doncaster said:

>
> > What is the generally accpted timeframe for renumbering? My reading of
> > ARIN policy would seem to imply at least 30 days.
[...]
> The bottom line is the space is theirs and they can do whatever they want
> with it.

Is that true? I thought the space belongs to ARIN, and they loan it to
certain parties. Those parties can use the IPs in accordance with ARIN
rules.

-Ralph

s/ARIN/IANA/

but yes, registries allocate based upon rules (most ISPs are registries).
In theory, IANA could revoke 192.0.0.0/8, forcing the RiR's to revoke the
space, forcing the LiR's to revoke the space, and so on until Joe Blow's
/29 gets revoked.

In practice, this has not to my knowledge ever occured. If we ever do
reach a point where exhaustion of IPv4 is imminent, I would expect this
to occur. Presently, there is a voluntary request for unused address
space, but as long as it is voluntary, I don't expect there being
any meaningful return of unused space.