RFC 1375 (rfc1375) - Page 3 of 7

Suggestion for New Classes of IP Addresses

RFC 1375              New Classes of IP Addresses           October 1992


   device simply by directing it to a specific internet site as an E-
   Mail message.

   The scheme proposed by this paper proposes to make a slight change in
   one of the classes of network address in a manner which should not be
   a significant problem for implementing, and should not cause a
   significant hardship as the addresses to use for this purpose are not
   now allocated anyway, and may draw some of the drain which would have
   consumed Class C addresses in large quantity into quantities of Class
   F, H, or K addresses which waste less IP address space.

   This scheme I am proposing is to allow for very small networks (1 or
   2, 1-7, or 1-15, depending on the number of addresses the
   administrator of that site thinks he will need), by reconstructing
   the network address to include what is nominally part of the local
   address.  If bridges and routers (and other hardware and software) do
   not assume that only the last 8 bits make up a local address and
   permit smaller spaces for local addresses, then this method should
   not cause problems. Sites needing less than a close order of 256 IP
   addresses could simply apply for 2 or more contiguous blocks of Class
   F numbers.

   Currently, a Class C address consists of a 32-bit number in which the
   leftmost 3 bits consist of "110" [2]:

        The third type of address, class C, has a 21-bit network number
        and a 8-bit local address.  The three highest-order bits are set
        to 1-1-0.  This allows 2,097,152 class C networks.

                        1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |1 1 0|                    NETWORK              | Local Address |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                        Current Class C Address

   This memo proposes to change Class C addresses to be 4-bit numbers
   beginning with "1100":

   The third type of address, class C, has a 20-bit network number and a
   8-bit local address.  The four highest-order bits are set to 1-1-0-0,
   This allows 1,048,576 class C networks.








Robinson