A Two-bit Differentiated Services Architecture for the Internet
RFC 2638
Document | Type |
RFC - Informational
(July 1999; Errata)
Was draft-nichols-diff-svc-arch (individual)
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Authors | Lixia Zhang , Van Jacobson , Kathleen Nichols | ||
Last updated | 2020-01-21 | ||
Stream | Legacy stream | ||
Formats | plain text html pdf ps htmlized (tools) htmlized with errata bibtex | ||
Stream | Legacy state | (None) | |
Consensus Boilerplate | Unknown | ||
RFC Editor Note | (None) | ||
IESG | IESG state | RFC 2638 (Informational) | |
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group K. Nichols Request for Comments: 2638 V. Jacobson Category: Informational Cisco L. Zhang UCLA July 1999 A Two-bit Differentiated Services Architecture for the Internet 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 (1999). All Rights Reserved. Abstract This document was originally submitted as an internet draft in November of 1997. As one of the documents predating the formation of the IETF's Differentiated Services Working Group, many of the ideas presented here, in concert with Dave Clark's subsequent presentation to the December 1997 meeting of the IETF Integrated Services Working Group, were key to the work which led to RFCs 2474 and 2475 and the section on allocation remains a timely proposal. For this reason, and to provide a reference, it is being submitted in its original form. The forwarding path portion of this document is intended as a record of where we were at in late 1997 and not as an indication of future direction. The postscript version of this document includes Clark's slides as an appendix. The postscript version of this document also includes many figures that aid greatly in its readability. 1. Introduction This document presents a differentiated services architecture for the internet. Dave Clark and Van Jacobson each presented work on differentiated services at the Munich IETF meeting [2,3]. Each explained how to use one bit of the IP header to deliver a new kind of service to packets in the internet. These were two very different kinds of service with quite different policy assumptions. Ensuing discussion has convinced us that both service types have merit and that both service types can be implemented with a set of very similar Nichols, et al. Informational [Page 1] RFC 2638 Two-bit Differentiated Services Architecture July 1999 mechanisms. We propose an architectural framework that permits the use of both of these service types and exploits their similarities in forwarding path mechanisms. The major goals of this architecture are each shared with one or both of those two proposals: keep the forwarding path simple, push complexity to the edges of the network to the extent possible, provide a service that avoids assumptions about the type of traffic using it, employ an allocation policy that will be compatible with both long-term and short-term provisioning, make it possible for the dominant Internet traffic model to remain best-effort. The major contributions of this document are to present two distinct service types, a set of general mechanisms for the forwarding path that can be used to implement a range of differentiated services and to propose a flexible framework for provisioning a differentiated services network. It is precisely this kind of architecture that is needed for expedient deployment of differentiated services: we need a framework and set of primitives that can be implemented in the short-term and provide interoperable services, yet can provide a "sandbox" for experimentation and elaboration that can lead in time to more levels of differentiation within each service as needed. At the risk of belaboring an analogy, we are motivated to provide services tiers in somewhat the same fashion as the airlines do with first class, business class and coach class. The latter also has tiering built in due to the various restrictions put on the purchase. A part of the analogy we want to stress is that best effort traffic, like coach class seats on an airplane, is still expected to make up the bulk of internet traffic. Business and first class carry a small number of passengers, but are quite important to the economics of the airline industry. The various economic forces and realities combine to dictate the relative allocation of the seats and to try to fill the airplane. We don't expect that differentiated services will comprise all the traffic on the internet, but we do expect that new services will lead to a healthy economic and service environment. This document is organized into sections describing service architecture, mechanisms, the bandwidth allocation architecture, how this architecture might interoperate with RSVP/int-serv work, and gives recommendations for deployment. Nichols, et al. Informational [Page 2]Show full document text