IETF - Overlapping IPv4 Address Support

[nanog.guru at gmail.com (Guru NANOG)]

Adding four more bits to the Left of the Source Address and setting
those bits to 1111 (0xF) can help to start the migration to "Regions"
and more IPv4 Addresses - Using and Re-Using legacy
spectrumhttp://www.iana.org/assignments/ipv4-address-space/ipv4-address-space.txt

16 /8s for "Future use" - it looks like the "Future" has arrived

240/8  Future use                                     1981-09
          RESERVED    [15]
   241/8  Future use                                     1981-09
             RESERVED    [15]
   242/8  Future use
                                   ...
 253/8  Future use                                     1981-09
           RESERVED    [15]
   254/8  Future use                                     1981-09
             RESERVED    [15]
   255/8  Future use                                     1981-09
             RESERVED  [15]

http://tools.ietf.org/html/draft-gundavelli-v6ops-community-wifi-svcs-014.13.
Overlapping IPv4 Address Support Wi-Fi Service Provider may segment the
network into regions. Two regions may use overlap IPv4 address space. This
is particularly important when the Internet is transitioning to IPv6. The
Wi-Fi SP may not have enough unique public IPv4 addresses to globally
address large number of Wi-Fi device.