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Per Hop Behavior Identification Codes (RFC2836)

IP.com Disclosure Number: IPCOM000003435D
Original Publication Date: 2000-May-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 5 page(s) / 12K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

S. Brim: AUTHOR [+3]

Abstract

Differentiated Services [RFC 2474, RFC 2475] introduces the notion of Per Hop Behaviors (PHBs) that define how traffic belonging to a particular behavior aggregate is treated at an individual network node. In IP packet headers, PHBs are not indicated as such; instead Differentiated Services Codepoint (DSCP) values are used. There are only 64 possible DSCP values, but there is no such limit on the number of PHBs. In a given network domain, there is a locally defined mapping between DSCP values and PHBs. Standardized PHBs recommend a DSCP mapping, but network operators may choose alternative mappings.

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Network Working Group S. Brim

Request for Comments: 2836 B. Carpenter

Category: Standards Track F. Le Faucheur

May 2000

Per Hop Behavior Identification Codes

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 (2000). All Rights Reserved.

Table of Contents:

1. Introduction................................................. 1

1.1. Usage Scenarios............................................ 2

2. Encoding..................................................... 3

3. IANA Considerations.......................................... 4

4. Security considerations...................................... 4

References...................................................... 4

Authors' Addresses.............................................. 5

Intellectual Property........................................... 6

Full Copyright Statement........................................ 7

1. Introduction

Differentiated Services [RFC 2474, RFC 2475] introduces the notion of

Per Hop Behaviors (PHBs) that define how traffic belonging to a

particular behavior aggregate is treated at an individual network

node. In IP packet headers, PHBs are not indicated as such; instead

Differentiated Services Codepoint (DSCP) values are used. There are

only 64 possible DSCP values, but there is no such limit on the

number of PHBs. In a given network domain, there is a locally defined

mapping between DSCP values and PHBs. Standardized PHBs recommend a

DSCP mapping, but network operators may choose alternative mappings.

In some cases it is necessary or desirable to identify a particular

PHB in a protocol message, such as a message negotiating bandwidth

management or path selection, especially when such messages pass

between management domains. Examples where work is in progress

include communication between bandwidth brokers, and MPLS support of

diffserv.

In certain cases, what needs to be identified is not an individual

PHB, but a set of PHBs. One example is a set of PHBs that must follow

the same physical path to prevent re-ordering. An instance of this

is the set of three PHBs be...