RFC 3408 (rfc3408) - Page 1 of 7

Zero-byte Support for Bidirectional Reliable Mode (R-mode) in Extended Link-Layer Assisted RObust Header Compression (ROHC) Profile

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Network Working Group                                             Z. Liu
Request for Comments: 3408                                         K. Le
Category: Standards Track                                          Nokia
                                                           December 2002


       Zero-byte Support for Bidirectional Reliable Mode (R-mode)
       in Extended Link-Layer Assisted RObust Header Compression
                             (ROHC) Profile

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 (2002).  All Rights Reserved.

Abstract

   This document defines an additional mode of the link-layer assisted
   RObust Header Compression (ROHC) profile, also known as the zero-byte
   profile, beyond the two defined in RFC 3242.  Zero-byte header
   compression exists in order to prevent the single-octet ROHC header
   from pushing a packet voice stream into the next higher fixed packet
   size for the radio.  It is usable in certain widely deployed older
   air interfaces.  This document adds the zero-byte operation for ROHC
   Bidirectional Reliable mode (R-mode) to the ones specified for
   Unidirectional (U-mode) and Bidirectional Optimistic (O-mode) modes
   of header compression in RFC 3242.

1.  Introduction

   [RFC 3242] defines a zero-byte solution for compression of IP/UDP/RTP
   packets only for Unidirectional (U-) and Bidirectional Optimistic
   (O-) modes [RFC 3095].  The present specification extends the profile
   defined in [RFC 3242] to provide zero-byte support for Bidirectional
   Reliable (R-) mode.  This specification and [RFC 3242] allow a
   header-free packet format to be used in all modes to replace the
   majority of the 1-octet headers of ROHC RTP packets sent during
   normal operation.  Specifically, the compressor operating in R-mode
   is allowed to deliver a No-Header Packet (NHP) when [RFC 3242] would
   have required it to deliver a ROHC Reliable Packet Type Zero (R-0)
   packet [RFC 3095].



Liu & Le                    Standards Track
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