IETF AUTOCONF Shubhranshu. Singh Internet-Draft JaeHoon. Kim Expires: August 18, 2005 SAMSUNG AIT Charles E. Perkins Nokia Research Center Pedro M. Ruiz University of Murcia Thomas. Clausen Ecole polytechnique February 14, 2005 Ad hoc network autoconfiguration: definition and problem statement draft-singh-autoconf-adp-00.txt Status of this Memo This document is an Internet-Draft and is subject to all provisions of Section 3 of RFC 3667. 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 become aware will be disclosed, in accordance with RFC 3668. 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 August 18, 2005. Copyright Notice Copyright (C) The Internet Society (2005). Abstract Singh, et al. Expires August 18, 2005 [Page 1] Internet-Draft Ad hoc network autoconfiguration: definition and problem statement February 2005 A Mobile Ad hoc Network (MANET) is formed by the association of wireless and mobile devices capable of communicating among themselves even if there is no networking infrastructure available. The autonomous nature of these networks, requires the existence of an autoconfiguration mechanism. This document provides definition, problem statement and solution guidelines for ad hoc network autoconfiguration. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Assumption . . . . . . . . . . . . . . . . . . . . . . . . . 7 4. Problem statement . . . . . . . . . . . . . . . . . . . . . . 8 4.1 Stand-alone ad hoc network . . . . . . . . . . . . . . . . 8 4.2 Ad hoc network at the edge of infra-structure network . . 8 4.3 Temporarily hybrid ad hoc network . . . . . . . . . . . . 9 4.4 Dealing with network merges and partitions . . . . . . . . 10 5. Autoconfiguration solution guidelines . . . . . . . . . . . . 11 6. Security Considerations . . . . . . . . . . . . . . . . . . . 12 7. Normative References . . . . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 12 Intellectual Property and Copyright Statements . . . . . . . . 14 Singh, et al. Expires August 18, 2005 [Page 2] Internet-Draft Ad hoc network autoconfiguration: definition and problem statement February 2005 1. Introduction A Mobile Ad hoc Network (MANET) is formed by the association of wireless and mobile devices capable of communicating among themselves even if there is no networking infrastructure avaiplable. However, it is generally expected that, if some MANET nodes are connected to external networks (e.g. Internet) some of them might act as gateways towards those networks. There are a number of solutions on interconnecting ad hoc networks to Internet[4][5][7]. Most of the solutions are tightly related to the issue of autoconfiguring global addresses routable in the Internet, and discovering Internet gateways at the same time. However, it is generally expected that autoconfiguration of addresses in MANET is also required even when the MANET is isolated from external networks. Currently there is no standard definition for commonly used ad hoc network autoconfiguration related terminologies such as manet local prefix, manet local address, etc. This document provides definition of such terminologies in addition to problem statement and solution guidelines for ad hoc network autoconfiguration. Singh, et al. Expires August 18, 2005 [Page 3] Internet-Draft Ad hoc network autoconfiguration: definition and problem statement February 2005 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", "OPTIONAL", and "silently ignore" in this document are to be interpreted as described in RFC 2119 [1]. Mobile Ad hoc Network (MANET) - A network formed by a set of mobile devices equipped with one or more wireless interfaces. Nodes are characterized by random mobility and run ad hoc routing protocols for multi-hop communication. MANET Node - A device with one or more wireless interfaces and associated IPv4 or IPv6 address which is used by the MANET routing protocol in use. MANET local address - An IPv4 or IPv6 address configured on a MANET node, which is valid for communication among manet nodes that are part of the same ad hoc network. Nodes MUST NOT communicate with other nodes outside the MANET using this address. Manet local prefix - Predefined network prefix used by manet nodes to generate address for communication within the multi-hop environment. Global address - An IPv4 or IPv6 address configured on a MANET node, which is valid for communication with the nodes located in the Internet. These addresses can also be used for communication with nodes within the MANET. Internet gateway - A node connected to ad hoc network as well as to the Internet and capable of providing global addressing and bidirectional connectivity to MANET nodes. Internet gateways should provide topologically correct IPv6 prefixes. This process can be done in a reactive, proactive or hybrid manner. Internet gateway mostly runs ad hoc routing protocols as well as infrastructure network protocols such as OSPF. Interface identifier - An unique number associated to each interface of a MANET node, that can be used for the generation of a global address from a network prefix. Singh, et al. Expires August 18, 2005 [Page 4] Internet-Draft Ad hoc network autoconfiguration: definition and problem statement February 2005 Duplicate Address Detection (DAD) - The process by which a node confirms the uniqueness of an address it has already configured or wishes to configure. A node already equipped with an IP address participates in DAD in order to protect its IP address from being used by another node. Standalone ad hoc network - A network consisting of a group of MANET nodes capable of spontaneously creating a multi-hop ad hoc network without any connection (either direct of via gateways) to other IP networks such as the Internet. Hybrid ad hoc network - A network formed by a group of MANET nodes, capable of spontaneously forming a multi-hop ad hoc network, in which one or more of the nodes act as Internet Gateways providing access to other IP networks. They can be envisioned as a standalone MANET with one or more Internet Gateways taking part both in the MANET and in the external network. MANET nodes are able to get global addressing as well as bidirectional connectivity between these two networks. Internet Gateway discovery - The proccess by which a MANET node selects the Internet Gateway through which it can communicate with a destination located in the Internet. This process can be either integrated into ad hoc routing protocols, integrated into autoconf messages or introduced into an independent module. Internet Gateway selection - The process by which MANET nodes select the Internet gateway to be used to communicate a MANET node with a destination located in the Internet. This process is only required in hybrid ad hoc networks. Different metrics can be used to make that decission e.g. hop count, delay, node's processing capabilities, power, etc. Network merger - The process by which two or more ad hoc networks (either standalone or hybrid), previously disjoint, get connected. In general, this proccess happens as a consequence of the mobility of the nodes. When this happens, the autoconf process should be able to re-establish the uniqueness of manet-local and global addresses. Network partitioning Singh, et al. Expires August 18, 2005 [Page 5] Internet-Draft Ad hoc network autoconfiguration: definition and problem statement February 2005 - The process by which an ad hoc network (either standalone or hybrid) which was previously connected, gets split into two or more disconnected ad hoc networks. In general, this proccess happens as a consequence of the mobility of the nodes. When this happens, some of the routes in MANET nodes become invalid hence some nodes may become unreachable. Autoconfiguration mechanisms should take into account these situations, and be able to tolerate those partitions. Singh, et al. Expires August 18, 2005 [Page 6] Internet-Draft Ad hoc network autoconfiguration: definition and problem statement February 2005 3. Assumption - Routes between nodes in the ad hoc network MUST NOT leak into the Internet. - Network routes (those valid for an entire network prefix instead of just a single node) require reachability to every node which exists within the prefix, just as within the Internet. - A gateway can be treated as a default router for the Internet. - A gateway SHOULD maintain active routes for all nodes within the MANET which are actively engaged in communications with their partners in the Internet. - Nodes within the Internet cannot distinguish whether or not a gateway offers connectivity to an ad hoc network or some other sort of stub network. - If two gateways advertise connectivity to the same routing prefix, then those two gateways MUST coordinate their routing tables so that they exhibit equal reachability for all nodes within that routing prefix. - Multiple gateways may offer several different routing prefixes. A node may choose which gateway's routing prefix to use for autoconfiguration according to any convenient criterion; the methods for making the determination are not constrained to be only those specified within a MANET autoconfiguration protocol specification. - Autoconfigured addresses are likely to have lifetimes associated with them, and after the lifetime expires use of the address should be immediately discontinued. - When duplicate addresses are detected, the node which has had the address for the least amount of time MUST discontinue. Alternatively, BOTH nodes MUST discontinue using this address. Singh, et al. Expires August 18, 2005 [Page 7] Internet-Draft Ad hoc network autoconfiguration: definition and problem statement February 2005 4. Problem statement While there are several autoconfiguration specifications for IP-based infrastructured networks such as RFCs 2461, 2462, 3315, etc, currently there is no standard specification describing how ad hoc nodes can auto-configure their IP addresses. Due to unique characteristics of ad hoc networks such as multi-hop packet forwarding, lack of any infrastructure e.g. DHCP server, random mobility, etc, the specifications used by infrastructured network cannot be directly used for ad hoc node autoconfiguration. The main goal of the MANET autoconf is to develop solutions for IPv4 and IPv6 address auto-configuration that are either manet-local scope i.e. valid only within a particular ad hoc network or global scope i.e. addresses that are routable on the global Internet. The autoconfiguration protocol has to carefully distinguish between cases when a gateway offers a routing prefix, from the case when a "manet local" prefix has to be used since no routing prefix is available for the purpose. In this way, a single addressing solution is obtained, but just as within the Internet there are different kinds of addresses. Some parallels can be drawn between the "manet local" addressing and the "zeroconf" solution devised within the IETF working group of the same name. However, there may be differences which are discovered as more development occurs towards the specification of the address autoconfiguration protocol. 4.1 Stand-alone ad hoc network Such ad hoc networks are not connected to any external network and are self-sufficient in themselves. Such networks include conference networks, battlefield, surveillance, etc. For such MANETs, IPv4 and IPv6 address auto-configuration mechanism, duplicate address detection and resolution mechanisms will be developed considering the situation where nodes may be added or removed randomly. Any address autoconfiguration mechanism for such networks should take care of the lack of any pre-established and reliable address or prefix allocation agency. 4.2 Ad hoc network at the edge of infra-structure network Such network is shown in Fig.1. Singh, et al. Expires August 18, 2005 [Page 8] Internet-Draft Ad hoc network autoconfiguration: definition and problem statement February 2005 H1 | +---------------+ | Internet | +---------------+ * * * * GW1* * | GW2 | | ---N1 | / | | N4 | N2--- N5 | | N3-----------+ Fig. 1: Hybrid ad hoc network connected to Internet. Hybrid networks can be envisioned as stand-alone networks connected to the Internet via one or more Internet Gateways. These gateways are located between the two networks. Internet gateways may be either fixed or mobile, single or multiple, equipped with wired and/or wireless interfaces and should be able to provide global addressing as well as bidirectional connectivity to the MANET nodes connected to it either directly (1-hop) or through one or more intermediate nodes. MANET nodes may use Internet gateways for prefix allocation. This may make the address configuration process comparatively simpler but it introduces other issues such as how MANET nodes receive or Internet gateways provide topologically correct routing prefixes. Hence, for such network sufficient but limited detail about Internet gateway discovery and operation will be provided, along with an address autoconfiguration solution. 4.3 Temporarily hybrid ad hoc network The third scenario considers the case in which an ad hoc network may be stand-alone for most of the time but temporarily connected to the infrastructured network (e.g. a car network connected while parked and disconnected otherwise). In this case, the nodes in the ad hoc network SHOULD maintain their allocated addresses for the lifetime which has been assigned during the autoconfiguration process. For manet-local addresses, no such lifetime is necessary, but could anyway be assigned as the most minimal protection against partitioning. Singh, et al. Expires August 18, 2005 [Page 9] Internet-Draft Ad hoc network autoconfiguration: definition and problem statement February 2005 4.4 Dealing with network merges and partitions Two or more ad hoc networks may join together or a single ad hoc network may get partitioned into two or more separate networks, at any moment in time. While network partitioning may not cause any severe problem in the MANET's operation, network merges may create some issues related to the possibility of introducing more than one node with the same address within the same MANET. Hence, appropriate mechanism should be provided in order to ensure uniqueness of the addresses configured by MANET nodes after a network merge. Singh, et al. Expires August 18, 2005 [Page 10] Internet-Draft Ad hoc network autoconfiguration: definition and problem statement February 2005 5. Autoconfiguration solution guidelines In order to offer a lightweight but interoperable auto-configuration mechanism a number of requirements SHOULD be satisfied. These requirements include: Extensibility - The mechanism SHOULD be able to accomodate future extensions and optimizations. Efficiency - Given that network resources tend to be scarce in MANETs, autoconfiguration mechanisms SHOULD be lightweight in nature, and avoid making an excessive use of the network resources. Independence from ad hoc routing protocols - Autoconfiguration mechanisms SHOULD be able to operate with different proactive and reactive routing protocols. Interoperable with fixed IP networks - When there are one or more Internet gateways within a MANET, the address autoconfiguration approach should provide global addresses to MANET nodes in such a way that they MUST be able to interoperate with any IP host in the Internet, using standard protocols. Resilience and robustness - Given the dynamic nature of MANETs, autoconfiguration mechanisms SHOULD be resilient and roubust to packet losses, network partitions, network merges as well as disconnections from fixed IP networks or Internet Gateways. Validity both for IPv4 and IPv6 - Autoconfiguration mechanisms SHOULD be capable of working both for IPV4 and IPv6 autoconfiguration. Scalable - MANET autoconfiguration protocols should avoid increasing congestion in the MANET as the number of MANET nodes increases, or as they travel at higher speeds, or as more communication partners launch applications within the ad hoc network, or as the frequency of network partitions increases. Singh, et al. Expires August 18, 2005 [Page 11] Internet-Draft Ad hoc network autoconfiguration: definition and problem statement February 2005 6. Security Considerations Since this document does not specify any protocol, no additional security vulnerabilities are created. However, experience with other address autoconfiguration protocols indicates that it is difficult to expect a very high degree of security. This is especially true in an ad hoc network using manet-local addresses, since it may be unfeasible to interact with any pre-existing security infrastructure. Nevertheless, the protocols should be designed to avoid as many security pitfalls as can be avoided. This may involve using collaboration histories and out-of-band mechanisms requiring user interventions. 7. Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Thomson, S. and T. Narten, "IPv6 Stateless Address Autoconfiguration", RFC 2462, December 1998. [3] Engelstad, P., Tonnesen, A., Hafslund, A. and G. Egeland, "Internet Connectivity for Multi-Homed Proactive Ad Hoc Networks", First IEEE International Conference on Sensor and Ad hoc Communications and Networks, October 2004. [4] Ryuji Wakikawa et. al. Global connectivity for IPv6 Mobile Ad Hoc Networks, IETF "draft-wakikawa-manet-globalv6-03.txt" [5] Shubhranshu Singh, Kim, JH., Choi, YG., Kang, KL. and YS. Roh, "Mobile multi-gateway support for IPv6 mobile ad hoc networks" I-D draft-singh-manet-mmg-00.txt, June 2004. [6] Perkins, C., Malinen, J., Wakikawa, R. and E. Belding-Royer, "IP Address Autoconfiguration for Ad Hoc Networks", I-D draft-perkins-manet-autoconf-01.txt, November 2001. [7] Cha, H., Park, J. and H. Kim, "Extended Support for Global Connectivity for IPv6 Mobile Ad Hoc Networks", October 2003. [8] Jeong, J., Park, J., Kim, H. and D. Kim, "Ad Hoc IP Address Autoconfiguration", I-D draft-jeong-adhoc-ip-addr-autoconf-02.txt, February 2004. [9] Paakkonen, P., Rantonen, M. and J. Latvakoski, "IPv6 addressing in a heterogeneous MANET-network", I-D draft-paakkonen-addressing-htr-manet-00.txt, December 2003. [10] Jelger, C., Noel, T. and A. Frey, "Gateway and address autoconfiguration for IPv6 adhoc networks", I-D draft-jelger-manet-gateway-autoconf-v6-02.txt, April 2004. [11] Sun, Y. and E. Belding-Royer, "A study of dynamic addressing techniques in mobile ad hod networks", I-D Wireless communication and mobile computing, May 2004. [12] Engelstad, P., Tonnesen, A., Hafslund, A. and G. Egeland, "Internet Connectivity for Multi-Homed Proactive Ad Hoc Networks", First IEEE International Conference on Sensor and Ad hoc Communications and Networks, October 2004. Authors' Addresses Shubhranshu Singh SAMSUNG Advanced Institute of Technology Comm & Network Lab San 14-1, Nongseo-ri, Giheung-eup Yongin-si, Gyeonggi-do 449-712 KOREA Phone: +82 31 280 9569 Email: shubranshu@gmail.com JaeHoon Kim SAMSUNG Advanced Institute of Technology Comm & Network Lab San 14-1, Nongseo-ri, Giheung-eup Yongin-si, Gyeonggi-do 449-712 KOREA Phone: +82 31 280 9532 Email: jaehoonk@samsung.com Singh, et al. Expires August 18, 2005 [Page 12] Internet-Draft Ad hoc network autoconfiguration: definition and problem statement February 2005 Charles E. Perkins Nokia Research Center Communications Systems Laboratory 313 Fairchild Drive Mountain View, CA 94303 USA Phone: +1 650 625 2986 Email: charliep@iprg.nokia.com Pedro M. Ruiz University of Murcia Dept. Information and Communications Eng. Facultad de Informatica Campus de Espinardo s/n, Gyeonggi-do 30100 Spain Phone: +34 968367646 Email: pedrom@dif.um.es Thomas Clausen Ecole polytechnique Project PCRI Pole Commun de Recherche en Informatique du plateau de Saclay CNRS, Ecole Polytechnique, Laboratoire d'informatique 91128 France Phone: +33 1 69 33 40 73 Email: T.Clausen@computer.org Singh, et al. Expires August 18, 2005 [Page 13] Internet-Draft Ad hoc network autoconfiguration: definition and problem statement February 2005 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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