RFC 1256 (rfc1256) - Page 1 of 19


ICMP Router Discovery Messages



Alternative Format: Original Text Document



Network Working Group                                 S. Deering, Editor
Request for Comments: 1256                                    Xerox PARC
                                                          September 1991


                     ICMP Router Discovery Messages

Status of this Memo

   This RFC specifies an IAB standards track protocol for the Internet
   community, and requests discussion and suggestions for improvements.
   Please refer to the current edition of the "IAB Official Protocol
   Standards" for the standardization state and status of this protocol.
   This document is a product of the IETF Router Discovery Working
   Group.  Distribution of this memo is unlimited.

Abstract

   This document specifies an extension of the Internet Control Message
   Protocol (ICMP) to enable hosts attached to multicast or broadcast
   networks to discover the IP addresses of their neighboring routers.

Table of Contents

   1. Terminology                                                      1
   2. Protocol Overview                                                3
   3. Message Formats                                                  5
   4. Router Specification                                             7
        4.1. Router Configuration Variables                            7
        4.2. Message Validation by Routers                             9
        4.3. Router Behavior                                           9
   5. Host Specification                                              12
        5.1. Host Configuration Variables                             12
        5.2. Message Validation by Hosts                              13
        5.3. Host Behavior                                            14
   6. Protocol Constants                                              17
   7. Security Considerations                                         17
   References                                                         18
   Author's Address                                                   19

1. Terminology

   The following terms have a precise meaning when used in this
   document:

   system        a device that implements the Internet Protocol, IP [9].

   router        a system that forwards IP datagrams, as specified



Router Discovery Working Group