RFC 3027 (rfc3027) - Page 1 of 20

Protocol Complications with the IP Network Address Translator

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Network Working Group                                        M. Holdrege
Request for Comments: 3027                                       ipVerse
Category: Informational                                     P. Srisuresh
                                                        Jasmine Networks
                                                            January 2001


     Protocol Complications with the IP Network Address Translator

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2001).  All Rights Reserved.

Abstract

   Many internet applications can be adversely affected when end nodes
   are not in the same address realm and seek the assistance of an IP
   Network Address Translator (NAT) enroute to bridge the realms.  The
   NAT device alone cannot provide the necessary application/protocol
   transparency in all cases and seeks the assistance of Application
   Level Gateways (ALGs) where possible, to provide transparency.  The
   purpose of this document is to identify the protocols and
   applications that break with NAT enroute.  The document also attempts
   to identify any known workarounds.  It is not possible to capture all
   applications that break with NAT in a single document.  This document
   attempts to capture as much information as possible, but is by no
   means a comprehensive coverage.  We hope the coverage provides
   sufficient clues for applications not covered.

Table of Contents

   1.0 Introduction ..............................................  2
   2.0 Common Characteristics of Protocols broken by NAT .........  2
   3.0 Protocols that cannot work with NAT enroute ...............  4
   4.0 Protocols that can work with the aid of an ALG ............  8
   5.0 Protocols designed explicitly to work with NAT enroute .... 16
   6.0 Acknowledgements .......................................... 17
   7.0 Security Considerations ................................... 17
   8.0 References ................................................ 17
   9.0 Authors' Addresses ........................................ 19
   10.0 Full Copyright Statement  ................................ 20




Holdrege & Srisuresh         Informational
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