Network Working Group                                          T. Narten
Request for Comments: 1970                                           IBM
Category: Standards Track                                    E. Nordmark
                                                        Sun Microsystems
                                                              W. Simpson
                                                              Daydreamer
                                                             August 1996


               Neighbor Discovery for IP Version 6 (IPv6)

Status of this Memo(RFC1661に同じ)

Abstract

   This document specifies the Neighbor Discovery protocol for IP
   Version 6.  IPv6 nodes on the same link use Neighbor Discovery to
   discover each other's presence, to determine each other's link-layer
   addresses, to find routers and to maintain reachability information
   about the paths to active neighbors.


1.  INTRODUCTION

   This specification defines the Neighbor Discovery (ND) protocol for
   Internet Protocol Version 6 (IPv6).  Nodes (hosts and routers) use
   Neighbor Discovery to determine the link-layer addresses for
   neighbors known to reside on attached links and to quickly purge
   cached values that become invalid.  Hosts also use Neighbor Discovery
   to find neighboring routers that are willing to forward packets on
   their behalf.  Finally, nodes use the protocol to actively keep track
   of which neighbors are reachable and which are not, and to detect
   changed link-layer addresses.  When a router or the path to a router
   fails, a host actively searches for functioning alternates.

   Unless specified otherwise (in a document that covers operating IP
   over a particular link type) this document applies to all link types.
   However, because ND uses link-layer multicast for some of its
   services, it is possible that on some link types (e.g., NBMA links)
   alternative protocols or mechanisms to implement those services will
   be specified (in the appropriate document covering the operation of
   IP over a particular link type).  The services described in this
   document that are not directly dependent on multicast, such as
   Redirects, Next-hop determination, Neighbor Unreachability Detection,
   etc., are expected to be provided as specified in this document.  The
   details of how one uses ND on NBMA links is an area for further
   study.

   The authors would like to acknowledge the contributions the IPNGWG
   working group and, in particular, (in alphabetical order) Ran
   Atkinson, Jim Bound, Scott Bradner, Alex Conta, Stephen Deering,
   Francis Dupont, Robert Elz, Robert Gilligan, Robert Hinden, Allison
   Mankin, Dan McDonald, Charles Perkins, Matt Thomas, and Susan
   Thomson.


2.  TERMINOLOGY(以下，略)