RFC 3290 (rfc3290) - Page 3 of 56


An Informal Management Model for Diffserv Routers



Alternative Format: Original Text Document



RFC 3290           Diffserv Informal Management Model           May 2002


1.  Introduction

   Differentiated Services (Diffserv) [DSARCH] is a set of technologies
   which allow network service providers to offer services with
   different kinds of network quality-of-service (QoS) objectives to
   different customers and their traffic streams.  This document uses
   terminology defined in [DSARCH] and [NEWTERMS] (some of these
   definitions are included here in Section 2 for completeness).

   The premise of Diffserv networks is that routers within the core of
   the network handle packets in different traffic streams by forwarding
   them using different per-hop behaviors (PHBs).  The PHB to be applied
   is indicated by a Diffserv codepoint (DSCP) in the IP header of each
   packet [DSFIELD].  The DSCP markings are applied either by a trusted
   upstream node, e.g., a customer, or by the edge routers on entry to
   the Diffserv network.

   The advantage of such a scheme is that many traffic streams can be
   aggregated to one of a small number of behavior aggregates (BA),
   which are each forwarded using the same PHB at the router, thereby
   simplifying the processing and associated storage.  In addition,
   there is no signaling other than what is carried in the DSCP of each
   packet, and no other related processing that is required in the core
   of the Diffserv network since QoS is invoked on a packet-by-packet
   basis.

   The Diffserv architecture enables a variety of possible services
   which could be deployed in a network.  These services are reflected
   to customers at the edges of the Diffserv network in the form of a
   Service Level Specification (SLS - see [NEWTERMS]).  Whilst further
   discussion of such services is outside the scope of this document
   (see [PDBDEF]), the ability to provide these services depends on the
   availability of cohesive management and configuration tools that can
   be used to provision and monitor a set of Diffserv routers in a
   coordinated manner.  To facilitate the development of such
   configuration and management tools it is helpful to define a
   conceptual model of a Diffserv router that abstracts away
   implementation details of particular Diffserv routers from the
   parameters of interest for configuration and management.  The purpose
   of this document is to define such a model.

   The basic forwarding functionality of a Diffserv router is defined in
   other specifications; e.g., [DSARCH, DSFIELD, AF-PHB, EF-PHB].

   This document is not intended in any way to constrain or to dictate
   the implementation alternatives of Diffserv routers.  It is expected
   that router implementers will demonstrate a great deal of variability
   in their implementations.  To the extent that implementers are able



Bernet, et. al.              Informational