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Compressing IP/UDP/RTP Headers for Low-Speed Serial Links (RFC2508)

IP.com Disclosure Number: IPCOM000003091D
Original Publication Date: 1999-Feb-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 20 page(s) / 57K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

S. Casner: AUTHOR [+2]

Abstract

This document describes a method for compressing the headers of IP/UDP/RTP datagrams to reduce overhead on low-speed serial links. In many cases, all three headers can be compressed to 2-4 bytes.

This text was extracted from a ASCII Text document.
This is the abbreviated version, containing approximately 5% of the total text.

Network Working Group S. Casner

Request for Comments: 2508 Cisco Systems

Category: Standards Track V. Jacobson

Cisco Systems

February 1999

Compressing IP/UDP/RTP Headers for Low-Speed Serial Links

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 (1999). All Rights Reserved.

Abstract

This document describes a method for compressing the headers of

IP/UDP/RTP datagrams to reduce overhead on low-speed serial links.

In many cases, all three headers can be compressed to 2-4 bytes.

Comments are solicited and should be addressed to the working group

mailing list rem-conf@es.net and/or the author(s).

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",

"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this

document are to be interpreted as described in RFC 2119.

1. Introduction

Since the Real-time Transport Protocol was published as an RFC [1],

there has been growing interest in using RTP as one step to achieve

interoperability among different implementations of network

audio/video applications. However, there is also concern that the

12-byte RTP header is too large an overhead for 20-byte payloads when

operating over low speed lines such as dial-up modems at 14.4 or 28.8

kb/s. (Some existing applications operating in this environment use

an application-specific protocol with a header of a few bytes that

has reduced functionality relative to RTP.)

Header size may be reduced through compression techniques as has been

done with great success for TCP [2]. In this case, compression might

be applied to the RTP header alone, on an end-to-end basis, or to the

combination of IP, UDP and RTP headers on a link-by-link basis.

Compressing the 40 bytes of combined headers together provides

substantially more gain than compressing 12 bytes of RTP header alone

because the resulting size is approximately the same (2-4 bytes) in

either case. Compressing on a link-by-link basis also provides

better performance because the delay and loss rate are lower.

Therefore, the method defined here is for combined compression of IP,

UDP and RTP headers on a link-by-link basis.

This document defines a compression scheme that may be used with

IPv4, IPv6 or packets encapsulated with more than one IP header,

though the initial focus is on IPv4. The IP/UDP/RTP compression

defined here is intended to fit wi...