RFC 2475: An Architecture for Differentiated Services | RFC Editor

Skip to content Primary navigationThe RFC SeriesFor AuthorsAbout UsHomeRFC 2475 View as: Plain Text, Compact HTML Info RFC 2475: An Architecture for Differentiated ServicesDiffservDecember 1998. S. Blake, D. Black, M. Carlson, E. Davies, Z. Wang, W. WeissInformationalSubscribe1 subscribed Add to Set Read aloud This RFC was updated, see RFC 3260.Network Working Group S. Blake Request for Comments: 2475 Torrent Networking Technologies Category: Informational D. Black EMC Corporation M. Carlson Sun Microsystems E. Davies Nortel UK Z. Wang Bell Labs Lucent Technologies W. Weiss Lucent Technologies December 1998 An Architecture for Differentiated Services 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 (1998). All Rights Reserved. Abstract This document defines an architecture for implementing scalable service differentiation in the Internet. This architecture achieves scalability by aggregating traffic classification state which is conveyed by means of IP-layer packet marking using the DS field [DSFIELD]. Packets are classified and marked to receive a particular per-hop forwarding behavior on nodes along their path. Sophisticated classification, marking, policing, and shaping operations need only be implemented at network boundaries or hosts. Network resources are allocated to traffic streams by service provisioning policies which govern how traffic is marked and conditioned upon entry to a differentiated services-capable network, and how that traffic is forwarded within that network. A wide variety of services can be implemented on top of these building blocks. Blake, et. al. Informational [Page 1] RFC 2475 Architecture for Differentiated Services December 1998 Table of Contents 1. Introduction ................................................. 2 1.1 Overview ................................................. 2 1.2 Terminology ............................................... 4 1.3 Requirements .............................................. 8 1.4 Comparisons with Other Approaches ......................... 9 2. Differentiated Services Architectural Model .................. 12 2.1 Differentiated Services Domain ............................ 12 2.1.1 DS Boundary Nodes and Interior Nodes .................. 12 2.1.2 DS Ingress Node and Egress Node ....................... 13 2.2 Differentiated Services Region ............................ 13 2.3 Traffic Classification and Conditioning ................... 14 2.3.1 Classifiers ........................................... 14 2.3.2 Traffic Profiles ...................................... 15 2.3.3 Traffic Conditioners .................................. 15 2.3.3.1 Meters ............................................ 16 2.3.3.2 Markers ........................................... 16 2.3.3.3 Shapers ........................................... 17 2.3.3.4 Droppers .......................................... 17 2.3.4 Location of Traffic Conditioners and MF Classifiers ... 17 2.3.4.1 Within the Source Domain .......................... 17 2.3.4.2 At the Boundary of a DS Domain .................... 18 2.3.4.3 In non-DS-Capable Domains ......................... 18 2.3.4.4 In Interior DS Nodes .............................. 19 2.4 Per-Hop Behaviors ......................................... 19 2.5 Network Resource Allocation ............................... 20 3. Per-Hop Behavior Specification Guidelines .................... 21 4. Interoperability with Non-Differentiated Services-Compliant Nodes ........................................................ 25 5. Multicast Considerations ..................................... 26 6. Security and Tunneling Considerations ........................ 27 6.1 Theft and Denial of Service ............................... 28 6.2 IPsec and Tunneling Interactions .......................... 30 6.3 Auditing .................................................. 32 7. Acknowledgements ............................................. 32 8. References ................................................... 33 Authors' Addresses ............................................... 34 Full Copyright Statement ......................................... 36 1. Introduction 1.1 Overview This document defines an architecture for implementing scalable service differentiation in the Internet. A "Service" defines some significant characteristics of packet transmission in one direction across a set of one or more paths within a network. These Blake, et. al. Informational [Page 2] RFC 2475 Architecture for Differentiated Services December 1998 characteristics may be specified in quantitative or statistical terms of throughput, delay, jitter, and/or loss, or may otherwise be specified in terms of some relative priority of access to network resources. Service differentiation is desired to accommodate heterogeneous application requirements and user expectations, and to permit differentiated pricing of Internet service. This architecture is composed of a number of functional elements implemented in network nodes, including a small set of per-hop forwarding behaviors, packet classification functions, and traffic conditioning functions including metering, marking, shaping, and policing. This architecture achieves scalability by implementing complex classification and conditioning functions only at network boundary nodes, and by applying per-hop behaviors to aggregates of traffic which have been appropriately marked using the DS field in the IPv4 or IPv6 headers [DSFIELD]. Per-hop behaviors are defined to permit a reasonably granular means of allocating buffer and bandwidth resources at each node among competing traffic streams. Per- application flow or per-customer forwarding state need not be maintained within the core of the network. A distinction is maintained between: o the service provided to a traffic aggr