WKBI #586, Redploying most of 127/8 as unicast public

Thu Nov 18 10:51:33 UTC 2021

John Levine wrote on 18/11/2021 03:03:
> The amount of work to change every computer in the world running
> TCP/IP and every IP application to treat 240/4 as unicast (or to treat
> some of 127/8) is not significantly less than the work to get them to
> support IPv6. So it would roughly double the work, for a 2% increase
> in the address space, or for 127/8 less than 1%.  The code for IPv6
> is already written, after all.
> 
> Also, while the world has run out of free IPv4 address space, there is
> plenty of IPv4 if you are willing to pay for it. A 2% increase in v4
> addresses would not change that.

putting more numbers on the table, the pre-exhaustion burn rate of 
unallocated ipv4 address space was around 13 x /8 a year, i.e. a /8 
every four weeks.

The ask is to update every ip stack in the world (including validation, 
equipment retirement, reconfiguration, etc) and the gain is 4 weeks of 
extra ip address space in terms of estimated consumption.

Nick