Autoconf Working Group C. Jelger Internet-Draft Fraunhofer FOKUS Expires: October 14, 2006 April 12, 2006 MANET Local IPv6 Addresses draft-jelger-autoconf-mla-00.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. 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. This Internet-Draft will expire on October 14, 2006. Copyright Notice Copyright (C) The Internet Society (2006). Abstract This document defines how Unique Local IPv6 Unicast Addresses (RFC- 4193) can be used in wireless mobile ad hoc networks (MANETs) as MANET Local IPv6 Addresses (MLAs). MLAs are intended to be used inside a MANET and are not expected to be routable on the global Internet. Each MANET node is expected to generate its MLA locally without any coordination with other MANET nodes. Jelger Expires October 14, 2006 [Page 1] Internet-Draft MANET Local IPv6 Addresses April 2006 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 3 3. MANET Local IPv6 Addresses (MLAs) . . . . . . . . . . . . . . . 3 3.1. Format . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.2. Address generation . . . . . . . . . . . . . . . . . . . . 4 3.3. Address scope . . . . . . . . . . . . . . . . . . . . . . . 4 4. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 6 Intellectual Property and Copyright Statements . . . . . . . . . . 7 Jelger Expires October 14, 2006 [Page 2] Internet-Draft MANET Local IPv6 Addresses April 2006 1. Introduction This document defines a possible use of Unique Local IPv6 Unicast Addresses (ULAs)[1] as MANET Local IPv6 Addresses (MLAs) in wireless mobile ad hoc networks (MANETs). MLAs are intended to be used inside a MANET and are not expected to be routable on the global Internet. Each MANET node is expected to generate its MLA locally, i.e. without any coordination with other MANET nodes. This extends the usage of ULAs to an extreme case where each MANET node is considered as being a site and subnet [1] by itself. Since MANET routing is flat (i.e. it creates /128 host routes), MANET nodes do not necessarily need to share a network prefix for intra-MANET communications. This loose addressing model allows to use a large fraction of the upper 64-bit part of IPv6 addresses in order to create addresses that are sufficiently random to avoid the use of duplicate address detection schemes for intra-MANET communications. 2. Acknowledgements The idea of using Unique Local IPv6 Addresses as MANET Local Addresses has been originally discussed with a number of people including Ryuji Wakikawa, Francisco Ros, Robert Hinden, Brian Haberman and Guillaume Chelius. Therefore the author of this document does not claim exclusive credit. Also note that the formatting of this document is mostly inspired by [1]. 3. MANET Local IPv6 Addresses (MLAs) 3.1. Format Strictly speaking, MLAs have the same format as ULAs. The only difference with ULAs is that both the Global ID and Subnet ID fields are randomly generated. This results in a merged 56-bit field called the Random ID. | 7 bits |1| 56 bits | 64 bits | +--------+-+------------------------+----------------------------+ | Prefix |L| Random ID | Interface ID | +--------+-+------------------------+----------------------------+ Jelger Expires October 14, 2006 [Page 3] Internet-Draft MANET Local IPv6 Addresses April 2006 Where: Prefix FC00::/7 prefix to identify Local IPv6 unicast addresses. L Set to 1. See [1] for details. Random ID 56-bit random identifier used to create a globally unique address. Interface ID 64-bit Interface ID as defined in [2]. 3.2. Address generation To create an MLA for a given physical interface, a MANET node locally generates its Random ID in a random manner. Since MANET routing is flat and creates /128 host routes, MANET nodes do not need to share a network prefix. Hence the Random ID is used in addition to the Interface ID in order to create unique addresses (with a very high probability of uniqueness). Using 56 bits gives around 7.2e+16 possible values for the Random ID, hence drastically reducing the probability of an address collision if two nodes having the same Interface ID generate the same Random ID. The probability of an address collision is further reduced by the use of EUI-64 identifiers as Interface IDs. EUI-64 that derive from EUI-48 (e.g. IEEE 802 48-bit MAC addresses) are indeed expected to be globally unique, while randomly generated identifiers [3] have an extremely low collision probability (around 1.8e+19 possible values). Given the network size currently being considered within the MANET community (a few hundred nodes), and given the extremely large randomness of MLAs, a node must not necessarily check whether a generated MLA is unique. The overhead of performing duplicate address detection (DAD) greatly superseeds its gain since the probability of address collisions is extremely low. Nevertheless, a passive DAD technique could be used in order to detect address collisions, eventhough such events are very unlikely to occur. This extra mechanism is however out of the scope of this document. 3.3. Address scope As Unique Local IPv6 Unicast Addresses, MANET Local Addresses have a global scope. However MLAs are not globally routeable, and their use is restricted inside a MANET. Since there does not exist any standardized definition of the boundaries of a MANET, we assume that Jelger Expires October 14, 2006 [Page 4] Internet-Draft MANET Local IPv6 Addresses April 2006 the use of MLAs is restricted to the set of MANET nodes (or routing instances) willing to route packets using MLAs. This assumes that a MANET routing protocol should always be willing to route packets whose source and/or destination addresses are MLAs. 4. References [1] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast Addresses", RFC 4193, October 2005. [2] Hinden, R. and S. Deering, "Internet Protocol Version 6 (IPv6) Addressing Architecture", RFC 3513, April 2003. [3] Narten, T. and R. Draves, "Privacy Extensions for Stateless Address Autoconfiguration in IPv6", RFC 3041, January 2001. Jelger Expires October 14, 2006 [Page 5] Internet-Draft MANET Local IPv6 Addresses April 2006 Author's Address Christophe Jelger Fraunhofer Institute FOKUS Kaiserin-Augusta-Allee 31 Berlin 10589 Germany Phone: +49 30 3463 7137 Email: cje@fokus.fraunhofer.de Jelger Expires October 14, 2006 [Page 6] Internet-Draft MANET Local IPv6 Addresses April 2006 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. 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Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM 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. Copyright Statement Copyright (C) The Internet Society (2006). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Jelger Expires October 14, 2006 [Page 7]