RFC 3320 (rfc3320) - Page 2 of 62

Signaling Compression (SigComp)

RFC 3320            Signaling Compression (SigComp)         January 2003


Table of Contents

   1.  Introduction...................................................2
   2.  Terminology....................................................3
   3.  SigComp architecture...........................................5
   4.  SigComp dispatchers...........................................15
   5.  SigComp compressor............................................18
   6.  SigComp state handler.........................................20
   7.  SigComp message format........................................23
   8.  Overview of the UDVM..........................................28
   9.  UDVM instruction set..........................................37
   10. Security Considerations.......................................56
   11. IANA Considerations...........................................58
   12. Acknowledgements..............................................59
   13. References....................................................59
   14. Authors' Addresses............................................60
   15. Full Copyright Statement......................................62

1.  Introduction

   Many application protocols used for multimedia communications are
   text-based and engineered for bandwidth rich links.  As a result the
   messages have not been optimized in terms of size.  For example,
   typical SIP messages range from a few hundred bytes up to two
   thousand bytes or more [RFC 3261].

   With the planned usage of these protocols in wireless handsets as
   part of 2.5G and 3G cellular networks, the large message size is
   problematic.  With low-rate IP connectivity the transmission delays
   are significant.  Taking into account retransmissions, and the
   multiplicity of messages that are required in some flows, call setup
   and feature invocation are adversely affected.  SigComp provides a
   means to eliminate this problem by offering robust, lossless
   compression of application messages.

   This document outlines the architecture and prerequisites of the
   SigComp solution, the format of the SigComp message and the Universal
   Decompressor Virtual Machine (UDVM) that provides decompression
   functionality.

   SigComp is offered to applications as a layer between the application
   and an underlying transport.  The service provided is that of the
   underlying transport plus compression.  SigComp supports a wide range
   of transports including TCP, UDP and SCTP [RFC-2960].







Price, et. al.              Standards Track