Compressing IP/UDP/RTP Headers for Low-Speed Serial Links (RFC2508)
Original Publication Date: 1999-Feb-01
Included in the Prior Art Database: 2019-Feb-11
Internet Society Requests For Comment (RFCs)
S. Casner: AUTHOR [+1]
This document describes a method for compressing the headers of IP/UDP/RTP datagrams to reduce overhead on low-speed serial links. [STANDARDS-TRACK]
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 (C) The Internet Society (1999). All Rights Reserved.
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 firstname.lastname@example.org 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.
Since the Real-time Transport Protocol was published as an RFC , 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 [Page 1]
RFC 2508 Compressing IP/UDP/RTP Headers February 1999
Header size may be reduced through compression techniques as has been done with great success for TCP . 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 within the more general compression framework specified in  for use with both IPv6 and IPv4. That framework defines TCP and non-TCP as two classes of transport above IP. This specification creates IP/UDP/RTP...