RFC 2508 (rfc2508) - Page 1 of 24

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

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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  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.)






Casner & Jacobson           Standards Track
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