Assigned numbers
RFC 870

Document Type RFC - Historic (October 1983; No errata)
Obsoleted by RFC 900
Obsoletes RFC 820
Last updated 2013-03-02
Stream Legacy
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Network Working Group                                        J. Reynolds
Request for Comments: 870                                      J. Postel
                                                                     ISI
Obsoletes RFCs:  820,                                       October 1983
790, 776, 770, 762, 758, 755,
750, 739, 604, 503, 433, 349
Obsoletes IENs:  127, 117, 93

                            ASSIGNED NUMBERS

This Network Working Group Request for Comments documents the currently
assigned values from several series of numbers used in network protocol
implementations.  This RFC will be updated periodically, and in any case
current information can be obtained from Joyce Reynolds.  The assignment
of numbers is also handled by Joyce.  If you are developing a protocol
or application that will require the use of a link, socket, port,
protocol, or network number please contact Joyce to receive a number
assignment.

   Joyce Reynolds
   USC - Information Sciences Institute
   4676 Admiralty Way
   Marina del Rey, California  90292

   phone: (213) 822-1511

   ARPA mail: JKREYNOLDS@USC-ISIF

Most of the protocols mentioned here are documented in the RFC series of
notes.  The more prominent and more generally used are documented in the
"Internet Protocol Transition Workbook" [16] or in the old "ARPANET
Protocol Handbook" [17] prepared by the NIC.  Some of the items listed
are undocumented.  Further information on protocols can be found in the
memo "Official Protocols" [52].

In all cases the name and mailbox of the responsible individual is
indicated.  In the lists that follow, a bracketed entry, e.g., [16,iii],
at the right hand margin of the page indicates a reference for the
listed protocol, where the number cites the document and the "iii" cites
the person.

Reynolds & Postel                                               [Page 1]



Assigned Numbers                                                 RFC 870
Network Numbers

                        ASSIGNED NETWORK NUMBERS

   The network numbers listed here are used as internet addresses by the
   Internet Protocol (IP) [16,47].  The IP uses a 32-bit address field
   and divides that address into a network part and a "rest" or local
   address part.  The division takes 3 forms or classes.

      The first type of address, or class A, has a 7-bit network number
      and a 24-bit local address.  The highest-order bit is set to 0.
      This allows 128 class A 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 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|   NETWORK   |                Local Address                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                             Class A Address

      The second type of address, class B, has a 14-bit network number
      and a 16-bit local address.  The two highest-order bits are set to
      1-0.  This allows 16,384 class B 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 0|           NETWORK         |          Local Address        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                             Class B Address

      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 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                             Class C Address

      Note:  No addresses are allowed with the three highest-order bits
      set to 1-1-1.  These addresses (sometimes called "class D") are
      reserved.

Reynolds & Postel                                               [Page 2]



Assigned Numbers                                                 RFC 870
Network Numbers

   One commonly used notation for internet host addresses divides the
   32-bit address into four 8-bit fields and specifies the value of each
   field as a decimal number with the fields separated by periods.  This
   is called the "dotted decimal" notation.  For example, the internet
   address of ISIF in dotted decimal is 010.002.000.052, or 10.2.0.52.

   The dotted decimal notation will be used in the listing of assigned
   network numbers.  The class A networks will have nnn.rrr.rrr.rrr, the
   class B networks will have nnn.nnn.rrr.rrr, and the class C networks
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