Network Working Group S. Daniel Park Internet-Draft SAMSUNG Electronics Expires : January 2004 July 2003 Requirement for Optimized DAD in IPv6 Mobility Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026 except that the right to produce derivative works is not granted [1]. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress". The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Abstract This document describes requirements how optimized DAD should be used for IPv6 mobility. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [2]. Park Expires - January 2004 [Page 1] Internet-Draft Requirement for Optimized DAD July 2003 Table of Contents 1. Introduction..................................................2 2. Intention / Scenario..........................................2 3. Requirements for optimized DAD................................3 3.1 Comparison with original DAD.............................3 3.2 Neighbor Cache...........................................3 3.3 Host Modifications.......................................3 3.4 Router modifications.....................................3 3.5 Security.................................................4 3.6 Address Duplication Considerations.......................4 3.7 Layer 2 Considerations...................................4 4. IANA Considerations...........................................4 5. Security Considerations.......................................4 6. References....................................................4 7. Authors' Addresses............................................5 8. Acknowledgements..............................................5 9. Copyright.....................................................5 1. Introduction In order to generate unique address, an IPv6 node has to perform DAD (Duplicate Address Detection) procedure when the IPv6 node tries to make its own IPv6 address including link-local and global address. Recently, some considerations are being suggested for optimized DAD mechanisms to provide fast handover when a mobile node is connected to the new networks. Real-time services require layer 3 handovers between IPv6 networks to be completed quickly and with minimal packet loss. All IPv6 nodes must perform DAD every time they handover between IPv6 networks. DAD described in [3] is a time consuming process, particularly when nodes in need of seamless handover run it. During DAD time, any active communications of nodes are interrupted, and this is especially unsuitable for real-time services. This document clarifies the requirements for optimized DAD in IPv6 mobility. 2. Intention / Scenario The intention is to minimize address configuration delays in the successful case without greatly increasing disruption in the less likely failure case. Optimized DAD is a useful when a DAD is far more Park Expires - January 2004 [Page 2] Internet-Draft Requirement for Optimized DAD July 2003 likely to succeed than fail for randomly autoconfigured addresses. This makes it worth a little disruption in the failure case to provide faster handovers in the successful case, as long as the disruption is easily recoverable. 3. Requirements for optimized DAD The purpose of the optimized DAD mechanism is to provide faster handovers in IPv6 mobility. 3.1 Comparison with original DAD When an original DAD is performed to verify address duplication, there happened to be some delays (is defined in [3]) in this case. In order to reduce delays, optimized DAD should be required to provide faster handover in the IPv6 mobility. Though, at the same time, it should be noted that the optimized DAD MUST NOT break the original DAD mechanism. 3.2 Neighbor Cache The Neighbor Cache entries MUST NOT be modified in a way which is unrecoverable through original DAD operation [3]. For effective optimized DAD, there are no restrictive requirements to modify Neighbor Cache entry in the specific cases. 3.3 Host Modifications The optimized DAD SHOULD allow for the use of original DAD and NDP (Neighbor Discovery Protocol) to a host even if a host wants to be modified for optimized DAD. For optimized DAD, a host including neighbor MUST recognize modifications such as specific fields, flags, values, etc. 3.4 Router modifications The optimized DAD SHOULD allow for the use of original DAD and NDP to a router even if a router wants to be modified for optimized DAD. For optimized DAD, a router MUST provide host requirements. Park Expires - January 2004 [Page 3] Internet-Draft Requirement for Optimized DAD July 2003 3.5 Security The optimized DAD scheme SHOULD NOT introduce any new attacks on Neighbor Discovery and the resulting schemes should be no worse than existing DAD [3]. There are existing security concerns with Neighbor Discovery and Stateless Address Autoconfiguration. These schemes SHOULD interwork with Secure Neighbor DAD mechanisms as defined in SEND WG. 3.6 Address Duplication Considerations In the simplest collision case, the address being configured by the new node is already in use by another node, and present in the Neighbor Caches of neighbors which are communicating with this node. At this case, all nodes MUST detect address duplication either original DAD or optimized DAD. 3.7 Layer 2 Considerations Generally, address duplication is happened to the same Interface ID which is composed of 48bit/64bit MAC address. Therefore, when same MAC address is existed in the same link, one of these nodes can not make its IPv6 address using address autoconfiguration mechanism. At this case, all nodes MUST be allowed to generate new addresses by another mechanism. It should be clarified that the mechanisms should be more discussed in the near future. 4. IANA Considerations There are no IANA considerations in this document. 5. Security Considerations Section 3.5 specifies security requirements for optimized DAD 6. References [1] Bradner, S., "The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996. Park Expires - January 2004 [Page 4] Internet-Draft Requirement for Optimized DAD July 2003 [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [3] Thomson, S., Narten, T., "IPv6 Stateless Address Autocon- figuration" RFC 2462, December 1998. [4] Narten, T. et. al., "Neighbor Discovery for IPv6" RFC 2461, December 1998. 7. Author's Address Soohong Daniel Park Mobile Platform Laboratory, SAMSUNG Electronics EMail: soohong.park@samsung.com 8. Acknowledgements Specially thanks are due to Greg Delay for many useful comments. 9. Copyright The following copyright notice is copied from RFC 2026 [Bradner,1996], Section 10.4, and describes the applicable copyright for this document. Copyright (C) The Internet Society July 12, 2001. All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assignees. Park Expires - January 2004 [Page 5] Internet-Draft Requirement for Optimized DAD July 2003 This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Park Expires - January 2004 [Page 6]