RFC 3086 (rfc3086) - Page 1 of 24

Definition of Differentiated Services Per Domain Behaviors and Rules for their Specification

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Network Working Group                                         K. Nichols
Request for Comments: 3086                                 Packet Design
Category: Informational                                     B. Carpenter
                                                                     IBM
                                                              April 2001


       Definition of Differentiated Services Per Domain Behaviors
                   and Rules for their Specification

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2001).  All Rights Reserved.

Abstract

   The differentiated services framework enables quality-of-service
   provisioning within a network domain by applying rules at the edges
   to create traffic aggregates and coupling each of these with a
   specific forwarding path treatment in the domain through use of a
   codepoint in the IP header.  The diffserv WG has defined the general
   architecture for differentiated services and has focused on the
   forwarding path behavior required in routers, known as "per-hop
   forwarding behaviors" (or PHBs).  The WG has also discussed
   functionality required at diffserv (DS) domain edges to select
   (classifiers) and condition (e.g., policing and shaping) traffic
   according to the rules.  Short-term changes in the QoS goals for a DS
   domain are implemented by changing only the configuration of these
   edge behaviors without necessarily reconfiguring the behavior of
   interior network nodes.

   The next step is to formulate examples of how forwarding path
   components (PHBs, classifiers, and traffic conditioners) can be used
   to compose traffic aggregates whose packets experience specific
   forwarding characteristics as they transit a differentiated services
   domain.  The WG has decided to use the term per-domain behavior, or
   PDB, to describe the behavior experienced by a particular set of
   packets as they cross a DS domain.  A PDB is characterized by
   specific metrics that quantify the treatment a set of packets with a
   particular DSCP (or set of DSCPs) will receive as it crosses a DS
   domain.  A PDB specifies a forwarding path treatment for a traffic
   aggregate and, due to the role that particular choices of edge and



Nichols & Carpenter          Informational
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