Optimistic Duplicate Address Detection (DAD) for IPv6
RFC 4429
Document | Type |
RFC - Proposed Standard
(April 2006; Errata)
Updated by RFC 7527
|
|
---|---|---|---|
Author | Nick Moore | ||
Last updated | 2015-10-14 | ||
Stream | Internent Engineering Task Force (IETF) | ||
Formats | plain text html pdf htmlized (tools) htmlized bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 4429 (Proposed Standard) | |
Action Holders |
(None)
|
||
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Margaret Cullen | ||
Send notices to | (None) |
Network Working Group N. Moore Request for Comments: 4429 Monash University CTIE Category: Standards Track April 2006 Optimistic Duplicate Address Detection (DAD) for 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. Copyright Notice Copyright (C) The Internet Society (2006). Abstract Optimistic Duplicate Address Detection is an interoperable modification of the existing IPv6 Neighbor Discovery (RFC 2461) and Stateless Address Autoconfiguration (RFC 2462) processes. The intention is to minimize address configuration delays in the successful case, to reduce disruption as far as possible in the failure case, and to remain interoperable with unmodified hosts and routers. Moore Standards Track [Page 1] RFC 4429 Optimistic DAD April 2006 Table of Contents 1. Introduction ....................................................3 1.1. Problem Statement ..........................................3 1.2. Definitions ................................................4 1.3. Address Types ..............................................4 1.4. Abbreviations ..............................................5 2. Optimistic DAD Behaviors ........................................6 2.1. Optimistic Addresses .......................................6 2.2. Avoiding Disruption ........................................6 2.3. Router Redirection .........................................7 2.4. Contacting the Router ......................................7 3. Modifications to RFC-Mandated Behavior ..........................8 3.1. General ....................................................8 3.2. Modifications to RFC 2461 Neighbor Discovery ...............8 3.3. Modifications to RFC 2462 Stateless Address Autoconfiguration ..........................................9 4. Protocol Operation .............................................10 4.1. Simple Case ...............................................10 4.2. Collision Case ............................................10 4.3. Interoperation Cases ......................................11 4.4. Pathological Cases ........................................11 5. Security Considerations ........................................12 Appendix A. Probability of Collision ..............................13 A.1. The Birthday Paradox ......................................13 A.2. Individual Moving Nodes ...................................14 Normative References ..............................................15 Informative References ............................................15 Acknowledgements ..................................................16 Moore Standards Track [Page 2] RFC 4429 Optimistic DAD April 2006 1. Introduction Optimistic Duplicate Address Detection (DAD) is a modification of the existing IPv6 Neighbor Discovery (ND) [RFC2461] and Stateless Address Autoconfiguration (SLAAC) [RFC2462] processes. The intention is to minimize address configuration delays in the successful case, and to reduce disruption as far as possible in the failure case. Optimistic DAD is a useful optimization because in most cases DAD is far more likely to succeed than fail. This is discussed further in Appendix A. Disruption is minimized by limiting nodes' participation in Neighbor Discovery while their addresses are still Optimistic. It is not the intention of this memo to improve the security, reliability, or robustness of DAD beyond that of existing standards, but merely to provide a method to make it faster. 1.1. Problem Statement The existing IPv6 address configuration mechanisms provide adequate collision detection mechanisms for the fixed hosts they were designed for. However, a growing population of nodes need to maintain continuous network access despite frequently changing their network attachment. Optimizations to the DAD process are required to provide these nodes with sufficiently fast address configuration. An optimized DAD method needs to: * provide interoperability with nodes using the current standards. * remove the RetransTimer delay during address configuration. * ensure that the probability of address collision is not increased.Show full document text