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        RFC 1517:

        Title:      Applicability Statement for the Implementation of
                    Classless Inter-Domain Routing (CIDR)
        Author:     Internet Engineering Steering Group
                    R. Hinden, Editor
        Mailbox:    hinden@eng.sun.com
        Pages:      4
        Characters: 7,357
        Updates/Obsoletes:  none


As the Internet has evolved and grown in recent years, it has become
clear that it will soon face several serious scaling problems.  These
include:

   1) Exhaustion of the class-B network address space. One
      fundamental cause of this problem is the lack of a network
      class of a size that is appropriate for a mid-sized
      organization. Class-C, with a maximum of 254 host addresses, is
      too small, while class-B, which allows up to 65534 addresses,
      is too large to be densely populated.  The result is inefficient
      utilization of class-B network numbers.

   2) Routing information overload. The size and rate of growth of the
      routing tables in Internet routers is beyond the ability of
      current software (and people) to effectively manage.

   3) Eventual exhaustion of IP network numbers.

It has become clear that the first two of these problems are likely to
become critical in the near term.  Classless Inter-Domain Routing
(CIDR) attempts to deal with these problems by defining a mechanism to
slow the growth of routing tables and reduce the need to allocate new
IP network numbers.  It does not attempt to solve the third problem,
which is of a more long-term nature, but instead endeavors to ease
enough of the short to mid-term difficulties to allow the Internet to
continue to function efficiently while progress is made on a
longer-term solution.  The IESG, after a thorough discussion in the
IETF, in June 1992 selected CIDR as the solution for the short term
routing table explosion problem.

This is now a Proposed Standard Protocol.

This RFC specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements.  Please refer to the current edition of the "Internet
Official Protocol Standards" for the standardization state and status
of this protocol.  Distribution of this memo is unlimited.

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Joyce K. Reynolds
USC/Information Sciences Institute