Network Working Group T. Narten
Request for Comments: 4861 IBM
Obsoletes: 2461 E. Nordmark
Category: Standards Track Sun Microsystems
W. Simpson
Daydreamer
H. Soliman
Elevate Technologies
September 2007
Neighbor Discovery for IP version 6 (IPv6)
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
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.
Narten, et al. Standards Track [Page 1]
RFC 4861 Neighbor Discovery in IPv6 September 2007
Table of Contents
1. Introduction ....................................................4
2. Terminology .....................................................4
2.1. General ....................................................4
2.2. Link Types .................................................8
2.3. Addresses ..................................................9
2.4. Requirements ..............................................10
3. Protocol Overview ..............................................10
3.1. Comparison with IPv4 ......................................14
3.2. Supported Link Types ......................................16
3.3. Securing Neighbor Discovery Messages ......................18
4. Message Formats ................................................18
4.1. Router Solicitation Message Format ........................18
4.2. Router Advertisement Message Format .......................19
4.3. Neighbor Solicitation Message Format ......................22
4.4. Neighbor Advertisement Message Format .....................23
4.5. Redirect Message Format ...................................26
4.6. Option Formats ............................................28
4.6.1. Source/Target Link-layer Address ...................28
4.6.2. Prefix Information .................................29
4.6.3. Redirected Header ..................................31
4.6.4. MTU ................................................32
5. Conceptual Model of a Host .....................................33
5.1. Conceptual Data Structures ................................33
5.2. Conceptual Sending Algorithm ..............................36
5.3. Garbage Collection and Timeout Requirements ...............37
6. Router and Prefix Discovery ....................................38
6.1. Message Validation ........................................39
6.1.1. Validation of Router Solicitation Messages .........39
6.1.2. Validation of Router Advertisement Messages ........39
6.2. Router Specification ......................................40
6.2.1. Router Configuration Variables .....................40
6.2.2. Becoming an Advertising Interface ..................45
6.2.3. Router Advertisement Message Content ...............45
6.2.4. Sending Unsolicited Router Advertisements ..........47
6.2.5. Ceasing To Be an Advertising Interface .............47
6.2.6. Processing Router Solicitations ....................48
6.2.7. Router Advertisement Consistency ...................50
6.2.8. Link-local Address Change ..........................50
6.3. Host Specification ........................................51
6.3.1. Host Configuration Variables .......................51
6.3.2. Host Variables .....................................51
6.3.3. Interface Initialization ...........................52
6.3.4. Processing Received Router Advertisements ..........53
6.3.5. Timing out Prefixes and Default Routers ............56
6.3.6. Default Router Selection ...........................56
datatracker.ietf.org