IP Network Address Translator (NAT) Terminology and Considerations (RFC2663)
Original Publication Date: 1999-Aug-01
Included in the Prior Art Database: 2019-Feb-11
Internet Society Requests For Comment (RFCs)
P. Srisuresh: AUTHOR [+1]
This document attempts to describe the operation of NAT devices and the associated considerations in general, and to define the terminology used to identify various flavors of NAT. This memo provides information for the Internet community.
Network Working Group P. Srisuresh Request for Comments: 2663 M. Holdrege Category: Informational Lucent Technologies August 1999
IP Network Address Translator (NAT) Terminology and Considerations
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 (C) The Internet Society (1999). All Rights Reserved.
The motivation behind this document is to provide clarity to the terms used in conjunction with Network Address Translators. The term "Network Address Translator" means different things in different contexts. The intent of this document is to define the various flavors of NAT and standardize the meaning of terms used.
The authors listed are editors for this document and owe the content to contributions from members of the working group. Large chunks of the document titled, "IP Network Address Translator (NAT)" were extracted almost as is, to form the initial basis for this document. The editors would like to thank the authors Pyda Srisuresh and Kjeld Egevang for the same. The editors would like to thank Praveen Akkiraju for his contributions in describing NAT deployment scenarios. The editors would also like to thank the IESG members Scott Bradner, Vern Paxson and Thomas Narten for their detailed review of the document and adding clarity to the text.
Network Address Translation is a method by which IP addresses are mapped from one realm to another, in an attempt to provide transparent routing to hosts. Traditionally, NAT devices are used to connect an isolated address realm with private unregistered addresses to an external realm with globally unique registered addresses. This document attempts to describe the operation of NAT devices and the associated considerations in general, and to define the terminology used to identify various flavors of NAT.
Srisuresh & Holdrege Informational [Page 1]
RFC 2663 NAT Terminology and Considerations August 1999
1. Introduction and Overview
The need for IP Address translation arises when a network’s internal IP addresses cannot be used outside the network either because they are invalid for use outside, or because the internal addressing must be kept private from the external network.
Address translation allows (in many cases, except as noted in sections 8 and 9) hosts in a private network to transparently communicate with destinations on an external network and vice versa. There are a variety of flavors of NAT and terms to match them. This document attempts to define the terminology used and to identify various flavors of NAT. The document also attempts to describe other considerations applicable to NAT devices in general.
Note, however, this document is not intended to describe the operations of individual NAT variations or the applicability of NAT devices.
NAT devices attempt to provide a transparent routing solution to end hosts trying to commu...