RFC 2962 (rfc2962) - Page 2 of 20

An SNMP Application Level Gateway for Payload Address Translation

RFC 2962            SNMP Payload Address Translation        October 2000


   This document includes a detailed description of the requirements and
   limitations for an implementation of an SNMP Application Level
   Gateway.  It also discusses other approaches to exchange SNMP packets
   across conflicting addressing realms.

Table of Contents

   1.  Introduction ..................................................2
   2.  Terminology and Concepts Used  ................................5
   3.  Problem Scope and Requirements ................................5
   3.1 IP Addresses in SNMP Messages  ................................6
   3.2 Requirements ..................................................7
   4.  Translating IP Addresses in SNMP Packets ......................7
   4.1 Basic SNMP Application Level Gateway ..........................8
   4.2 Advanced SNMP Application Level Gateway  ......................8
   4.3 Packet Size and UDP Checksum ..................................9
   5.  Limitations and Alternate Solutions  .........................10
   6.  Security Considerations  .....................................12
   7.  Summary and Recommendations  .................................13
   8.  Current Implementations  .....................................14
   9.  Acknowledgments  .............................................14
   10. References ...................................................14
   11. Authors' Addresses ...........................................16
   12. Description of the Encoding of SNMP Packets  .................17
   13. Full Copyright Statement .....................................20

1. Introduction

   The need for IP address translation arises when a network's internal
   IP addresses cannot be used outside the network.  Using basic network
   address translation allows local hosts on such private networks
   (addressing realms) to transparently access the external global
   Internet and enables access to selective local hosts from the
   outside.  In particular it is not unlikely to have several addressing
   realms that are using the same private IPv4 address space within the
   same organization.

   In many of these cases, there is a need to manage the local
   addressing realm from a manager site outside the domain. However,
   managing such a network presents unique problems and challenges.
   Most available management applications use SNMP (Simple Network
   Management Protocol) to retrieve information from the network
   elements.  For example, a router may be queried by the management
   application about the addresses of its neighboring elements.  This
   information is then sent by the router back to the management






Raz, et al.                  Informational