RFC 3287 (rfc3287) - Page 3 of 120

Remote Monitoring MIB Extensions for Differentiated Services

RFC 3287                       DSMON MIB                      July 2002


   o  A set of fundamental applications described in RFC 2573 [RFC 2573]
      and the view-based access control mechanism described in RFC 2575
      [RFC 2575].

   A more detailed introduction to the current SNMP Management Framework
   can be found in RFC 2570 [RFC 2570].

   Managed objects are accessed via a virtual information store, termed
   the Management Information Base or MIB.  Objects in the MIB are
   defined using the mechanisms defined in the SMI.

   This memo specifies a MIB module that is compliant to the SMIv2.  A
   MIB conforming to the SMIv1 can be produced through the appropriate
   translations.  The resulting translated MIB must be semantically
   equivalent, except where objects or events are omitted because no
   translation is possible (use of Counter64).  Some machine readable
   information in SMIv2 will be converted into textual descriptions in
   SMIv1 during the translation process.  However, this loss of machine
   readable information is not considered to change the semantics of the
   MIB.

2.  Overview

   There is a need for a standardized way of monitoring the network
   traffic usage of Differentiated Services (DS) [RFC 2474] codepoint
   values.  Each DS codepoint (DSCP) value may be given a different
   treatment by a forwarding device, and this affects which packets get
   dropped or delayed during periods of network congestion.

   The IETF DIFFSERV working group has redefined the semantics of the
   Type of Service (TOS) octet in the IP header, which is now called the
   'DS field'.  The 6-bit Codepoint (DSCP) portion is contained in the
   DS field, which provides for 64 different packet treatments for the
   implementation of differentiated network services.

   By polling DSCP usage counters, an NMS can determine the network
   throughput for traffic associated with different DSCPs.  This data
   can then be analyzed in order to 'tune' DSCP 'allocations' within a
   network, based on the Quality of Service (QoS) policies for that
   network.

   Remote monitoring agents are typically implemented as independent
   software (and sometimes hardware) components, called 'RMON probes'.
   Note that DSMON-capable RMON probes simply collect and aggregate
   statistics, based on criteria (which includes the DSCP value) that
   can be determined by inspecting the contents of monitored packets and
   do not in any way monitor any aspect of a DS forwarding device's
   internal statistics.



Bierman                     Standards Track