Autoconf Working Group C. Jelger Internet-Draft University of Basel Expires: April 8, 2007 October 5, 2006 MANET Local IPv6 Addresses draft-jelger-autoconf-mla-01.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 April 8, 2007. 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 router is expected to generate its MLA locally without any coordination with other MANET routers. Jelger Expires April 8, 2007 [Page 1] Internet-Draft MANET Local IPv6 Addresses October 2006 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. MANET Local IPv6 Addresses (MLAs) . . . . . . . . . . . . . . . 3 3.1. Format . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.2. Address generation . . . . . . . . . . . . . . . . . . . . 4 3.3. Address scope . . . . . . . . . . . . . . . . . . . . . . . 4 4. Host configuration . . . . . . . . . . . . . . . . . . . . . . 5 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 7 Intellectual Property and Copyright Statements . . . . . . . . . . 8 Jelger Expires April 8, 2007 [Page 2] Internet-Draft MANET Local IPv6 Addresses October 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 router is expected to generate its MLA locally, i.e. without any coordination with other MANET routers. This extends the usage of ULAs to an extreme case where each MANET router is considered as being a site and subnet [1] by itself. In this particular case, routing is flat and MANET routers do not share a network prefix. 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. Terminology This document employs the following terms (partly borrowed from [2]): Node Any device (router or host) which implements IP. MANET Router (MR) A router that engages in a MANET routing protocol. In certain scenarios, a MR may forward packets for hosts attached to it. Host Any node that is not a router, i.e. it does not forward packets addressed to others. 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. To indicate this difference with ULAs, the L bit is set to 0. Hence in practise ULAs use FD00::/8 and MLAs use FC00::/8. | 8 bits | 56 bits | 64 bits | +----------+------------------------+----------------------------+ | Prefix | Random ID | Interface ID | +----------+------------------------+----------------------------+ Jelger Expires April 8, 2007 [Page 3] Internet-Draft MANET Local IPv6 Addresses October 2006 Where: Prefix FC00::/8 prefix to identify MANET Local addresses. (L bit of ULAs is set to 0). Random ID 56-bit random identifier used to create a globally unique address. Interface ID 64-bit Interface ID as defined in [3]. 3.2. Address generation To create an MLA for a given physical interface, a MANET router locally generates its Random ID in a random manner. The Random ID is used in addition to the Interface ID in order to create an address 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 routers 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 [4] 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 the use of MLAs is restricted to the set of MANET nodes willing to route, send, and receive 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. Jelger Expires April 8, 2007 [Page 4] Internet-Draft MANET Local IPv6 Addresses October 2006 4. Host configuration If non-router hosts are attached to a MANET router, the MANET router may advertise the upper 64 bits of its MLA (i.e. a /64 prefix) to its attached hosts. This can be done via router advertisement messages as in IPv6 stateless address autoconfiguration [5]. Each host generates its MLA by appending an interface ID to the MLA prefix advertised by the MANET router it is attached to. To allow communications between hosts attached to different MANET routers, MANET routers MUST exchange and use /64 routes. Since the hosts attached to a given MANET router may not always be able to directly communicate one with another (e.g. if they are out of radio transmision range), the L bit of the Prefix Information Option of the router advertisement message must be set to 0 to indicate that the prefix is off-link (see page 30 of [6]). As a result, hosts receiving the router advertisement message do not create a subnet route (i.e. a /64 route) for the advertised prefix. Hence two hosts attached to a given MANET router communicate by default via the MANET router (as in 802.11 infrastructure mode). 5. 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]. Useful comments for version 00 of this draft have been given by Fred Templin and Joe Macker. When possible, their suggestions have been included in this new version. In particular, Fred Templin suggested first that the L bit is set to 0. 6. References [1] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast Addresses", RFC 4193, October 2005. [2] Chakeres, I., Macker, J., and T. Clausen, "Mobile Ad Hoc Network Architecture", I-D draft-chakeres-manet-arch-00, July 2006. [3] Hinden, R. and S. Deering, "Internet Protocol Version 6 (IPv6) Addressing Architecture", RFC 3513, April 2003. [4] Narten, T. and R. Draves, "Privacy Extensions for Stateless Jelger Expires April 8, 2007 [Page 5] Internet-Draft MANET Local IPv6 Addresses October 2006 Address Autoconfiguration in IPv6", RFC 3041, January 2001. [5] Thomson, S. and T. Narten, "IPv6 Stateless Address Autoconfiguration", RFC 2462, December 1998. [6] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery for IP Version 6 (IPv6)", RFC 2461, December 1998. Jelger Expires April 8, 2007 [Page 6] Internet-Draft MANET Local IPv6 Addresses October 2006 Author's Address Christophe Jelger University of Basel Bernoullistrasse 16 Basel 4056 Switzerland Phone: +41 61 267 0391 Email: Christophe.Jelger@unibas.ch Jelger Expires April 8, 2007 [Page 7] Internet-Draft MANET Local IPv6 Addresses October 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 April 8, 2007 [Page 8]