Gratuitous Neighbor Discovery: Creating Neighbor Cache Entries on First-Hop Routers
draft-ietf-6man-grand-03
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.
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material or to cite them other than as "work in progress."
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
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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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