A Framework for Policy-based Admission Control
RFC 2753

Document Type RFC - Informational (January 2000; No errata)
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Network Working Group                                         R. Yavatkar
Request for Comments: 2753                                          Intel
Category: Informational                                     D. Pendarakis
                                                                R. Guerin
                                                       U. Of Pennsylvania
                                                             January 2000

             A Framework for Policy-based Admission Control

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 (2000).  All Rights Reserved.

1. Introduction

   The IETF working groups such as Integrated Services (called "int-
   serv") and RSVP [1] have developed extensions to the IP architecture
   and the best-effort service model so that applications or end users
   can request specific quality (or levels) of service from an
   internetwork in addition to the current IP best-effort service.
   Recent efforts in the Differentiated Services Working Group are also
   directed at the definition of mechanisms that support aggregate QoS
   services. The int-serv model for these new services requires explicit
   signaling of the QoS (Quality of Service) requirements from the end
   points and provision of admission and traffic control at Integrated
   Services routers. The proposed standards for RSVP [RFC 2205] and
   Integrated Services [RFC 2211, RFC 2212] are examples of a new
   reservation setup protocol and new service definitions respectively.
   Under the int-serv model, certain data flows receive preferential
   treatment over other flows; the admission control component only
   takes into account the requester's resource reservation request and
   available capacity to determine whether or not to accept a QoS
   request.  However, the int-serv mechanisms do not include an
   important aspect of admission control: network managers and service
   providers must be able to monitor, control, and enforce use of
   network resources and services based on policies derived from
   criteria such as the identity of users and applications,
   traffic/bandwidth requirements, security considerations, and time-

Yavatkar, et al.             Informational                      [Page 1]
RFC 2753      Framework for Policy-based Admission Control  January 2000

   of-day/week. Similarly, diff-serv mechanisms also need to take into
   account policies that involve various criteria such as customer
   identity, ingress points, and so on.

   This document is concerned with specifying a framework for providing
   policy-based control over admission control decisions. In particular,
   it focuses on policy-based control over admission control using RSVP
   as an example of the QoS signaling mechanism. Even though the focus
   of the work is on RSVP-based admission control, the document outlines
   a framework that can provide policy-based admission control in other
   QoS contexts. We argue that policy-based control must be applicable
   to different kinds and qualities of services offered in the same
   network and our goal is to consider such extensions whenever

   We begin with a list of definitions in Section 2. Section 3 lists the
   requirements and goals of the mechanisms used to control and enforce
   access to better QoS.  We then outline the architectural elements of
   the framework in Section 4 and describe the functionality assumed for
   each component.  Section 5 discusses example policies, possible
   scenarios, and policy support needed for those scenarios. Section 6
   specifies the requirements for a client-server protocol for
   communication between a policy server (PDP) and its client (PEP) and
   evaluates the suitability of some existing protocols for this

2. Terminology

   The following is a list of terms used in this document.

   -  Administrative Domain: A collection of networks under the same
      administrative control and grouped together for administrative

   -  Network Element or Node: Routers, switches, hubs are examples of
      network nodes. They are the entities where resource allocation
      decisions have to be made and the decisions have to be enforced. A
      RSVP router which allocates part of a link capacity (or buffers)
      to a particular flow and ensures that only the admitted flows have
      access to their reserved resources is an example of a network
      element of interest in our context.

      In this document, we use the terms router, network element, and
      network node interchangeably, but the should all be interpreted as
      references to a network element.

   -  QoS Signaling Protocol: A signaling protocol that carries an
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