RFC 3593 (rfc3593) - Page 2 of 10

Textual Conventions for MIB Modules Using Performance History Based on 15 Minute Intervals

RFC 3593        15 Minute Based Performance History TCs   September 2003


1.  Introduction

   In cases where a manager must obtain performance history data about
   the behavior of equipment it manages, several strategies can be
   followed in the design of a MIB that represents the managed
   equipment, including:

   0  The agent counts events on a continuous basis and, whenever
      desired, the manager obtains the value of the event counter and
      adjusts its understanding of the history of events at the agent.

   0  The agent allocates events to 'buckets' where each bucket
      represents an interval of time.

   Telecommunications equipment often makes use of the latter strategy.
   See [3][4][5][7][8] for examples.  In particular, for this equipment
   it is common that history data is maintained by the agent in terms of
   fifteen minute intervals.

   This memo does not attempt to compare the relative merits of
   different strategies used to obtain history data.  Differences may
   include polling policy, the amount of management traffic between
   manager and agent, agent simplicity, and 'data currentness' of the
   data obtained by the manager.  MIB designers should consider these
   aspects when choosing a particular strategy in a MIB design.
   Instead, this memo provides definitions that can be used in MIB
   modules that require history data based on fifteen minute intervals.

   When designing a MIB module, it is often useful to define new types
   similar to those defined in the SMI [2].  In comparison to a type
   defined in the SMI, each of these new types has a different name, a
   similar syntax, but more precise semantics.  These newly defined
   types are termed textual conventions, and are used for the
   convenience of humans reading the MIB module.  This is done through
   Textual Conventions as defined in RFC 2579 [1].  It is the purpose of
   this document to define the set of textual conventions to be used
   when performance history based on 15 minute intervals is kept.  The
   performance history textual conventions defined in this memo are
   based on 32 bit counts.  For high capacity performance history counts
   see [9].

2.  Note on Invalid Data and Proxies

   In this document, the word proxy indicates an application which
   receives SNMP messages and replies to them on behalf of the devices
   where the actual implementation resides, e.g., DS3/E3 interfaces.
   The proxy will have already collected the information about the
   DS3/E3 interfaces into its local database and may not necessarily



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