Network Working Group                                         G. Deloche
Request for Comment: 7           University of California at Los Angeles
NIC: 4693                                                       May 1969


                           Host-Imp Interface



      G. Deloche      -->  Prof. J. Estrin
                           Prof. L. Kleinrock
                           Prof. B Bussel
                           D. Mandell
                           S. Crocker
                           L. Bonamy


   Object: Arpa Network - Specification Outlines for Host-IMP (HI)
   Interface Programs.



                                  Outline

   I.  Introduction

   II.  Scope of the software organization.
           II-1    Network program
           II-2    Handler program

   III.  Questions





   [The original of RFC 7 was hand-written, and only partially illegible
   copies exist.  RFC 7 was later typed int NLS by the Augmentation
   Research Center (ARC) at SRI.  The following is the best
   reconstruction we could do.  RFC Editor.]












 
RFC 7                      Host-IMP Interface                   May 1969


I.  Introduction

   This paper is concerned with the preliminary software design of the
   Host IMP interface.  Its main purpose is on the one hand to define
   functions that will be implemented, and on the other hand to provide
   a base for discussions and ...(unreadable).

   This study is based upon a study of the BBN Report No. 763.

II.  Scope of the software organization.

   The system is based upon two main programs: the Handler program that
   drives the channel hardware unit, and the Network program which
   carries out the user's transmission requests.

   As the communication is full duplex, each of these programs can be
   viewed as divided into two parts: one is concerned with the output
   data, the other with the input. (See Fig. 1)

   These two programs exchange data through a pool of buffers, and
   logical information through an interface table.

   In the following we only focus on the output part of each program
   (See Fig. 2).  The input part would be very similar.

II-1.   Network program.

II-1-1. Multiplex function.

   This program multiplexes the outgoing messages (and distributes the
   incoming messages).  The multiplexing consists in stacking up all the
   user's (or caller, or party) requests and filling up the pool of
   buffers so as to keep the handler busy emitting.

   Multiplexing (and distribution) is based on the link identification
   numbers.  (Link = logical connection between two users).  The
   multiplexing problem is closely related to the interface between a
   user's program and the network program, that is in