RFC 1136 (rfc1136) - Page 2 of 10

Administrative Domains and Routing Domains: A model for routing in the Internet

RFC 1136          A Model for Routing in the Internet      December 1989


   the present and future Internet, and to show how the model can aid in
   the construction of well-engineered routing environments.

4)  Terminology

   The following is a brief glossary of OSI terminology.  Formal
   definitions can be found in the OSI Basic Reference Model [4], the
   Internal Organization of the Network Layer [5], and the OSI Routeing
   Framework [1].

         "Routeing" is the official ISO spelling of what is more
         commonly spelled "routing."  In this paper, the ISO spelling
         will be used wherever directly quoted from ISO documents, and
         the common spelling used otherwise.

      End System (ES)

         An OSI system on which applications run.  An End System has
         full seven-layer OSI functionality.  Basically equivalent to an
         Internet Host.

      Intermediate System (IS)

         An OSI system that performs routing and relaying functions in
         order to provide paths between End Systems.  Intermediate
         Systems have no functionality above the Network Layer (although
         a practical realization of an OSI router will have some amount
         of End System functionality for network management functions,
         among other things).  Basically equivalent to an Internet
         Router.

      Subnetwork (SN)

         A communications medium that provides a "direct" path between
         Network Layer entities.  This can be realized via a point-to-
         point link, a LAN, a Public Data Network, and so forth.  This
         is essentially equivalent to an Internet Subnet.  It is worth
         noting that, unlike Internet Subnets, OSI Subnetworks are not
         necessarily reflected in the addressing hierarchy, so the
         double meaning of the Internet term "Subnet" (a single IP hop;
         a part of the address hierarchy) does not hold in the OSI
         world.

      Open Systems Interconnection Environment (OSIE)

         The global collection of Open Systems.  Basically equivalent to
         the Internet.




Hares & Katz