Gratuitous Neighbor Discovery: Creating Neighbor Cache Entries on First-Hop Routers
draft-ietf-6man-grand-00

Document Type Active Internet-Draft (6man WG)
Last updated 2020-03-09
Replaces draft-linkova-6man-grand
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IPv6 Maintenance                                              J. Linkova
Internet-Draft                                                    Google
Updates: 4861 (if approved)                                March 9, 2020
Intended status: Standards Track
Expires: September 10, 2020

Gratuitous Neighbor Discovery: Creating Neighbor Cache Entries on First-
                              Hop Routers
                        draft-ietf-6man-grand-00

Abstract

   Neighbor Discovery (RFC4861) is used by IPv6 nodes to determine the
   link-layer addresses of neighboring nodes as well as to discover and
   maintain reachability information.  This document updates [RFC4861]
   to allow routers to proactively create a Neighbor Cache entry when a
   new IPv6 address is assigned to a host.  It also updates [RFC4862]
   and recommends hosts to send unsolicited Neighbor Advertisements upon
   assigning a new IPv6 address.  The proposed change will minimize the
   delay and packet loss when a host initiate connections to off-link
   destination from a new IPv6 address.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on September 10, 2020.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of

Linkova                Expires September 10, 2020               [Page 1]
Internet-Draft                Gratuitous ND                   March 2020

   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     1.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Proposed Changes to Neighbor Discovery  . . . . . . . . . . .   4
     2.1.  Hosts Sending Gratuitous Neighbor Advertisements  . . . .   4
     2.2.  Routers Creating Cache Entries Upon Receiving Unsolicited
           Neighbor Advertisements . . . . . . . . . . . . . . . . .   5
   3.  Avoiding Disruption . . . . . . . . . . . . . . . . . . . . .   6
     3.1.  Neighbor Cache Entry Exists in Any State Other That
           INCOMPLETE  . . . . . . . . . . . . . . . . . . . . . . .   6
     3.2.  Neighbor Cache Entry Does Not Exist . . . . . . . . . . .   6
     3.3.  Neighbor Cache Entry is in INCOMPLETE state . . . . . . .   7
   4.  Modifications to RFC-Mandated Behavior  . . . . . . . . . . .   7
     4.1.  Modification to RFC4861 Neighbor Discovery for IP version
           6 (IPv6)  . . . . . . . . . . . . . . . . . . . . . . . .   7
       4.1.1.  Modification to the section 7.2.5 . . . . . . . . . .   7
       4.1.2.  Modification to the section 7.2.6 . . . . . . . . . .   8
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  10
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  10
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   The Neighbor Discovery state machine defined in [RFC4861] implies
   that communications between IPv6 nodes are in most cases bi-
   directional and if a host A is trying to communicate to its neighbor,
   host B, the return traffic flows could be expected.  So when the host
   A starts the address resolution process, the target host would also
   create an entry for the host A address in its neighbor cache.  That
   entry will be used for sending the return traffic to the host A.

   However when a host sends traffic to off-link destinations a
   different scenario is observed.  After receiving a Router
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