RFC 1028 (rfc1028) - Page 2 of 35

Simple Gateway Monitoring Protocol

RFC 1028               Simple Gateway Monitoring           November 1987


   (3)  The degree of management function that is remotely
        supported is accordingly increased, thereby imposing the
        fewest possible restrictions on the form and sophistication
        of management tools.

   (4)  A simplified set of management functions is easily
        understood and used by developers of gateway management
        tools.

   A second design goal is that the functional paradigm for monitoring
   and control be sufficiently extensible to accommodate additional,
   possibly unanticipated aspects of gateway operation.

   A third goal is that the design be, as much as possible, independent
   of the architecture and mechanisms of particular hosts or particular
   gateways.

   Consistent with the foregoing design goals are a number of decisions
   regarding the overall form of the protocol design.

   One such decision is to model all gateway management functions as
   alterations or inspections of various parameter values.  By this
   model, a protocol entity on a logically remote host (possibly the
   gateway itself) interacts with a protocol entity resident on the
   gateway in order to alter or retrieve named portions (variables) of
   the gateway state.  This design decision has at least two positive
   consequences:

   (1)  It has the effect of limiting the number of essential
        management functions realized by the gateway to two: one
        operation to assign a value to a specified configuration
        parameter and another to retrieve such a value.

   (2)  A second effect of this decision is to avoid introducing
        into the protocol definition support for imperative
        management commands: the number of such commands is in
        practice ever-increasing, and the semantics of such
        commands are in general arbitrarily complex.

   The exclusion of imperative commands from the set of explicitly
   supported management functions is unlikely to preclude any desirable
   gateway management operation.  Currently, most gateway commands are
   requests either to set the value of some gateway parameter or to
   retrieve such a value, and the function of the few imperative
   commands currently supported is easily accommodated in an
   asynchronous mode by this management model.  In this scheme, an
   imperative command might be realized as the setting of a parameter
   value that subsequently triggers the desired action.



Davin, Case, Fedor and Schoffstall