Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers (RFC2474)

Publication Summary

Differentiated services enhancements to the Internet protocol are intended to enable scalable service discrimination in the Internet without the need for per-flow state and signaling at every hop. A variety of services may be built from a small, well-defined set of building blocks which are deployed in network nodes. The services may be either end-to-end or intra-domain; they include both those that can satisfy quantitative performance requirements (e.g., peak bandwidth) and those based on relative performance (e.g., "class" differentiation). Services can be constructed by a combination of:

Country	United States
Language	English (United States)
Related Person(s)	(AUTHOR)  K. Nichols (AUTHOR)  S. Blake (AUTHOR)  F. Baker (AUTHOR)  D. Black
Copyright	Copyright (C) The Internet Society (1998). All Rights Reserved.

---

Continue to Text Preview →

Network Working Group K. Nichols

Request for Comments: 2474 Cisco Systems

Obsoletes: 1455, 1349 S. Blake

Category: Standards Track Torrent Networking Technologies

F. Baker

Cisco Systems

D. Black

EMC Corporation

December 1998

Definition of the Differentiated Services Field (DS Field)

in the IPv4 and IPv6 Headers

Status of this Memo

This document specifies an Internet standards track protocol for the

Internet community, and requests discussion and suggestions for

improvements. Please refer to the current edition of the "Internet

Official Protocol Standards" (STD 1) for the standardization state

and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (1998). All Rights Reserved.

Abstract

Differentiated services enhancements to the Internet protocol are

intended to enable scalable service discrimination in the Internet

without the need for per-flow state and signaling at every hop. A

variety of services may be built from a small, well-defined set of

building blocks which are deployed in network nodes. The services

may be either end-to-end or intra-domain; they include both those

that can satisfy quantitative performance requirements (e.g., peak

bandwidth) and those based on relative performance (e.g., "class"

differentiation). Services can be constructed by a combination of:

- setting bits in an IP header field at network boundaries

(autonomous system boundaries, internal administrative boundaries,

or hosts),

- using those bits to determine how packets are forwarded by the

nodes inside the network, and

- conditioning the marked packets at network boundaries in accordance

with the requirements or rules of each service.

The requirements or rules of each service must be set through

administrative policy mechanisms which are outside the scope of this

document. A differentiated services-compliant network node includes

a classifier that selects packets based on the value of the DS field,

along with buffer management and packet scheduling mechanisms capable

of delivering the specific packet forwarding treatment indicated by

the DS field value. Setting of the DS field and conditioning of the

temporal behavior of marked packets need only be performed at network

boundaries and may vary in complexity.

This document defines the IP header field, called the DS (for

differentiated services) field. In IPv4, it defines the layout of

the TOS octet; in IPv6, the Traffic Class octet. I...

Download This Document →

Back to Overview