RFC 46 (rfc46) - Page 2 of 17

ARPA Network protocol notes

RFC 46                ARPA Network Protocol Notes             April 1970


   does not preclude the existence of additional layers of protocol
   between several installations so long as the basic protocol remains
   supported.

   We feel that three facilities must be provided for in the initial
   protocol:

   1. Multi-path communication between two existing processes which know
      how to connect to each other.

   2. A standard way for a process to connect to the logger (logging
      process at a HOST) at a foreign HOST and request the creation of a
      user process.  (The login ritual may or may not be standardized.)

   3. A standard way for a newly created process to initiate pseudo-
      typewriter communication with the foreign process which requested
      its creation.

   The major differences between the protocol as proposed by Carr,
   Crocker, and Cerf and this proposal are the following:

   1. The dynamic reconnection strategy specified in Crocker's
      NWG/RFC 36 is reserved for future implementation.  We feel that
      its inclusion would unduly complicate the initial implementation
      of the protocol.  We outline a strategy for foreign process
      creation that does not require dynamic reconnection.  Nothing in
      this proposal precludes the implementation of dynamic reconnection
      at a later date.

   2. We propose that an "instance tag" be added to the socket
      identifier so as to separate sockets belonging to different
      processes of the same user coexisting at one HOST.

   3. The following NCP commands have been added:

      a. The ERR command specified in NWG/RFC 40 is included.

      b. BLK and RSM commands are presented as possible alternatives to
         the "cease on link" IMP command and SPD and RSM commands set
         forth in NWG/RFC 36.  Because these commands operate on socket
         connections rather than link numbers, they do not impede the
         implementation of socket connection multiplexing over a single
         link number, should that later prove desirable.

      c. An INT command that interrupts a process is specified.  We feel
         that it is highly important to be able to interrupt a process
         that may be engaged in unwanted computation or output.  To
         implement the interrupt as a special format within a normal