rfc943.txt

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            42  THINK-AS                                          [BJN1]
            43  BNL-AS                                              [GC]
      44-65534  Unassigned                                         [JBP]
        65535   Reserved                                           [JBP]









































Reynolds & Postel                                              [Page 18]



Assigned Numbers                                                 RFC 943
ARPANET Logical Addresses


                   ASSIGNED ARPANET LOGICAL ADDRESSES

   The ARPANET facility for "logical addressing" is described in
   RFC 878 [58].  A portion of the possible logical addresses are
   reserved for standard uses.

   There are 49,152 possible logical host addresses.  Of these, 256 are
   reserved for assignment to well-known functions.  Assignments for
   well-known functions are made by Joyce Reynolds.  Assignments for
   other logical host addresses are made by the NIC.

   Logical Address Assignments:

      Decimal    Description                                  References
      -------    -----------                                  ----------
      0          Reserved                                          [JBP]
      1          The BBN Core Gateways                              [MB]
      2-255      Unassigned                                        [JBP]
      256        Reserved                                          [JBP]































Reynolds & Postel                                              [Page 19]



Assigned Numbers                                                 RFC 943
ARPANET Link Numbers


                     ASSIGNED ARPANET LINK NUMBERS

   The word "link" here refers to a field in the original ARPANET
   Host/IMP interface leader.  The link was originally defined as an
   8-bit field.  Later specifications defined this field as the
   "message-id" with a length of 12 bits.  The name link now refers to
   the high order 8 bits of this 12-bit message-id field.  The Host/IMP
   interface is defined in BBN Report 1822 [8].

   The low-order 4 bits of the message-id field are called the sub-link.
   Unless explicitly specified otherwise for a particular protocol,
   there is no sender to receiver significance to the sub-link.  The
   sender may use the sub-link in any way he chooses (it is returned in
   the RFNM by the destination IMP), the receiver should ignore the
   sub-link.

   Link Assignments:

      Decimal   Description                                   References
      -------   -----------                                   ----------
      0         Reserved                                           [JBP]
      1-149     Unassigned                                         [JBP]
      150       Xerox NS IDP                                   [114,LLG]
      151       Unassigned                                         [JBP]
      152       PARC Universal Protocol                         [12,HGM]
      153       TIP Status Reporting                               [JGH]
      154       TIP Accounting                                     [JGH]
      155       Internet Protocol [regular]                  [35,80,JBP]
      156-158   Internet Protocol [experimental]             [35,80,JBP]
      159       Figleaf Link                                      [JBW1]
      160-194   Unassigned                                         [JBP]
      195       ISO-IP                                         [116,RXM]
      196-247   Experimental Protocols                             [JBP]
      248-255   Network Maintenance                                [JGH]
















Reynolds & Postel                                              [Page 20]



Assigned Numbers                                                 RFC 943
IEEE 802 SAP Numbers


                    IEEE 802 SAP NUMBERS OF INTEREST

   Some of the networks of all classes are IEEE 802 Networks.  These
   systems may use a Service Access Point field in much the same way the
   ARPANET uses the "link" field.  For further information and SAP
   number assignments, please contact: Mr. Maris Graube, Chairman, IEEE
   802, c/o Tektronix, P.O. Box 500, D/S 50-473, Beaverton,
   Oregon, 97077.

   Assignments:

      Service Access Point               Description          References
      --------------------               -----------          ----------
      decimal  binary
         96   01100000                   DOD IP              [35,79,JBP]

   The IEEE 802.3 header does not have a type field to indicate what
   protocol is used at the next level.  As a work around for this
   problem, one can put the Ethernet type field value in the IEEE 802.3
   header's length field and use the following test to determine the
   appropriate processing on receipt.

   If the value in the length field of the IEEE 802.3 header is greater
   than the Ethernet maximum packet length, then interpret the value as
   an Ethernet type field.  Otherwise, interpret the packet as an IEEE
   802.3 packet.
























Reynolds & Postel                                              [Page 21]



Assigned Numbers                                                 RFC 943
Ethernet Numbers


                      ETHERNET NUMBERS OF INTEREST

   Many of the networks of all classes are Ethernets (10Mb) or
   Experimental Ethernets (3Mb).  These systems use a message "type"
   field in much the same way the ARPANET uses the "link" field.

   If you need an Ethernet number, contact the XEROX Corporation, Office
   Products Division, Network Systems Administration Office, 333 Coyote
   Hill Road, Palo Alto, California, 94304.

   Assignments:

      Ethernet          Exp. Ethernet    Description          References
      -------------     -------------   -----------           ----------
      decimal  Hex      decimal  octal
         512   0200        512   1000   XEROX PUP                [1,HGM]
         513   0201        -      -     PUP Addr. Trans.           [HGM]
        1536   0600       1536   3000   XEROX NS IDP           [113,HGM]
        2048   0800        513   1001   DOD IP               [35,79,JBP]
        2049   0801        -      -     X.75 Internet              [HGM]
        2050   0802        -      -     NBS Internet               [HGM]
        2051   0803        -      -     ECMA Internet              [HGM]
        2052   0804        -      -     Chaosnet                   [HGM]
        2053   0805        -      -     X.25 Level 3               [HGM]
        2054   0806        -      -     ARP                    [63,DCP1]
        2055   0807        -      -     XNS Compatability          [HGM]
        2076   081C        -      -     Symbolics Private         [DCP1]
       32771   8003        -      -     Cronus VLN            [104,DT15]
       32772   8004        -      -     Cronus Direct         [104,DT15]
       32774   8006        -      -     Nestar                     [HGM]
       32784   8010        -      -     Excelan                    [HGM]
       32821   8035        -      -     Reverse ARP             [38,JCM]
       36864   9000        -      -     Loopback                   [HGM]

   The standard for transmission of IP datagrams over Ethernets and
   Experimental Ethernets is specified in RFC 894 [50] and RFC 895 [65]
   respectively.













Reynolds & Postel                                              [Page 22]



Assigned Numbers                                                 RFC 943
Address Resolution Protocol


            ASSIGNED ADDRESS RESOLUTION PROTOCOL PARAMETERS

   The Address Resolution Protocol (ARP) specified in RFC 826 [64] has
   several parameters.  The assigned values for these parameters are
   listed here.

   Assignments:

      Operation Code (op)

         1   REQUEST
         2   REPLY

      Hardware Type (hrd)

         Type   Description                                   References
         ----   -----------                                   ----------
           1    Ethernet (10Mb)                                    [JBP]
           2    Experimental Ethernet (3Mb)                        [JBP]
           3    Amateur Radio AX.25                                [PXK]
           4    Proton ProNET Token Ring                           [JBP]

      Protocol Type (pro)

         Use the same codes as listed in the section called "Ethernet
         Numbers of Interest".