RFC 1797 (rfc1797) - Page 2 of 4

Class A Subnet Experiment

RFC 1797               Class A Subnet Experiment              April 1995


      network number (and it should be easier to get a single class C
      allocated than to get an AS number allocated), and that this is a
      limited time experiment so that these addresses will be temporary.

      The low order octet of the 4-octet IPv4 address is for local use.
      It is expected that an address of this form will be used to
      identify a specific publicly accessible Internet host.

                +--------+-+-------+--------+--------+
                |   39   |0| low 15 bits AS | local  |
                +--------+-+-------+--------+--------+
   Case 2:

      In the second case, the high order bit of these 24 bits is one,
      and the remaining 23 bits are assigned by the IANA (currently
      reserved for future use).

                +--------+-+-------+--------+--------+
                |   39   |1| variable prefix + local |
                +--------+-+-------+--------+--------+

      The general intent is to find a way to assign to experimenters
      prefixes of differing lengths so that a variety of experiments can
      be conducted with the prefix/local-address boundary at different
      points.

   It is not intended that either of these address allocation schemes is
   the model for how subnetted class A addresses will be actually
   allocated in the future.

   It is expected, to make the experiment interesting, that some
   providers will use these addresses for servers supplying popular
   material via the Web or FTP.

   For example, if the service provider registered to use AS 690 wished
   to use this style of address to provide access to a server of popular
   information on local host 7, the address would be:

                +--------+--------+--------+--------+
                |   39   |    2   |   178  |    7   |
                +--------+--------+--------+--------+










IANA