Gratuitous Neighbor Discovery: Creating Neighbor Cache Entries on First-Hop Routers
draft-ietf-6man-grand-03

Document Type Active Internet-Draft (6man WG)
Last updated 2020-09-18 (latest revision 2020-09-15)
Replaces draft-linkova-6man-grand
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IPv6 Maintenance                                              J. Linkova
Internet-Draft                                                    Google
Updates: 4861 (if approved)                           September 15, 2020
Intended status: Standards Track
Expires: March 19, 2021

Gratuitous Neighbor Discovery: Creating Neighbor Cache Entries on First-
                              Hop Routers
                        draft-ietf-6man-grand-03

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 node.  It also updates RFC4861 and
   recommends nodes to send unsolicited Neighbor Advertisements upon
   assigning a new IPv6 address.  The proposed change will minimize the
   delay and packet loss when a node 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 March 19, 2021.

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 March 19, 2021                 [Page 1]
Internet-Draft                Gratuitous ND               September 2020

   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     1.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Solution Requirements . . . . . . . . . . . . . . . . . . . .   6
   4.  Proposed Changes to Neighbor Discovery  . . . . . . . . . . .   6
     4.1.  Nodes Sending Gratuitous Neighbor Advertisements  . . . .   6
     4.2.  Routers Creating Cache Entries Upon Receiving Unsolicited
           Neighbor Advertisements . . . . . . . . . . . . . . . . .   7
   5.  Avoiding Disruption . . . . . . . . . . . . . . . . . . . . .   8
     5.1.  Neighbor Cache Entry Exists in Any State Other That
           INCOMPLETE  . . . . . . . . . . . . . . . . . . . . . . .   8
     5.2.  Neighbor Cache Entry is in INCOMPLETE state . . . . . . .   8
     5.3.  Neighbor Cache Entry Does Not Exist . . . . . . . . . . .   9
       5.3.1.  The Rightful Owner Is Not Sending Packets From The
               Address . . . . . . . . . . . . . . . . . . . . . . .   9
       5.3.2.  The Rightful Owner Has Started Sending Packets From
               The Address . . . . . . . . . . . . . . . . . . . . .  10
   6.  Modifications to RFC-Mandated Behavior  . . . . . . . . . . .  11
     6.1.  Modification to RFC4861 Neighbor Discovery for IP version
           6 (IPv6)  . . . . . . . . . . . . . . . . . . . . . . . .  11
       6.1.1.  Modification to the section 7.2.5 . . . . . . . . . .  11
       6.1.2.  Modification to the section 7.2.6 . . . . . . . . . .  12
   7.  Solution Limitations  . . . . . . . . . . . . . . . . . . . .  13
   8.  Solutions Considered but Discarded  . . . . . . . . . . . . .  13
     8.1.  Do Nothing  . . . . . . . . . . . . . . . . . . . . . . .  14
     8.2.  Change to the Registration-Based Neighbor Discovery . . .  14
     8.3.  Host Sending NS to the Router Address from Its GUA  . . .  14
     8.4.  Host Sending Router Solicitation from its GUA . . . . . .  15
     8.5.  Routers Populating Their Caches by Gleaning From Neighbor
           Discovery Packets . . . . . . . . . . . . . . . . . . . .  16
     8.6.  Initiating Hosts-to-Routers Communication . . . . . . . .  16
     8.7.  Making the Probing Logic on Hosts More Robust . . . . . .  17
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