IETF - Overlapping IPv4 Address Support

Tue Mar 6 20:57:00 UTC 2012

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.