MANET Autoconfiguration (AUTOCONF) Ilkyun Park Internet-Draft Younghan Kim Expires: April 22, 2007 Namhi Kang Soongsil University October 23, 2006 Address Autoconfiguration for Hybrid Mobile Ad Hoc Networks draft-ikpark-autoconf-haa-02 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/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on April 22, 2007. Copyright Notice Copyright (C) The Internet Society (2006). Park, et al., Expires April 22, 2007 [Page 1] Internet-Draft HAA October 2006 Abstract Most of current address autoconfiguration mechanisms for MANET introduce significant load like message flooding, or are dependent on the underlying routing protocols. This document proposes a new mechanism that is intended to minimize these drawbacks. It is also designed to be applicable for hybrid MANET, where a MANET is connected to Internet through one or more Interet gateways. Table of Contents 1. Introduction 3 2. Terminology 4 3. IPv6 Address Autoconfiguration for Hybrid MANETs 6 3.1. Link-local DAD 6 3.2. Default Node Selection 6 3.3. HAA path 6 3.4. MANET-scope DAD and Global-scope Address Configuration 7 3.5. Autoconfiguration without Internet Gateway 8 4. HAA Message Formats 9 4.1. Default node option for RA message 9 4.2. Global Address Solicitation message 10 4.3. Node Address option for GS message 10 4.4. Global Address Advertisement message 11 4.5. Node confirm option for GA message 12 5. Security Considerations 15 6. Revision of the Draft 16 References 16 Author's Address 17 Intellectual Property Statement 17 Disclaimer of Validity 18 Copyright Statement 18 Park, et al., Expires April 22, 2007 [Page 2] Internet-Draft HAA October 2006 1. Introduction A Mobile Ad Hoc Network (MANET) is self-organized by wireless mobile nodes, without any pre-installed infrastructures. Data packets are delivered by multi-hop communication of nodes. A topology of MANET is changed frequently due to the nodes' mobility. Therefore, it is necessary to configure their addresses automatically. "Hybrid MANET" is a mobile ad hoc network that has connectivity to external networks. The connectivity is provided by special node called `Internet gateway'. If MANET nodes want to communicate with nodes on the external networks, the configured addresses must be globally unique. Recently, several solutions have been proposed to autoconfigure addresses to MANET nodes [9]. Most of solutions exploit either an independent algorithm and messages [5] or a mechanism combined with underlying MANET routing protocol [6]. But they still have some drawbacks. First, they introduce significant load like message full- flooding over a MANET. Second, they are coupled with the routig protocol and have more complex structure. This document describes a mechanism of address autoconfiguration for a hybrid MANET, called `Hybrid MANET Address Autoconfiguration' (HAA). The mechanism is intended to minimize message full-flooding. HAA autoconfigures IPv6 addresses to MANET nodes by using IPv6 Neighbor Discovery Protocol (NDP) [2-3] with some options and messages newly defined here. After this autoconfiguration process, each mobile node has two types of addresses: MANET-local address and global-scope address. Park, et al., Expires April 22, 2007 [Page 3] Internet-Draft HAA October 2006 2. Terminology Duplicate Address Detection (DAD) The process to determine the uniqueness of an address to be configured. If any node has already used the same address, the node that has performed DAD process must select another address and then execute DAD process again. Hybrid MANET A MANET with a connection to the Internet is refered to as a hybrid MANET. Such a connectivity is provided by one or more Internet Gateways. Every node in hybrid MANET can have multiple addresses to be accessible to variable scope of networks. MANET-local Address An address used in MANET-scope communications. Internet gateways do not forward the packets that have MANET-local addresses as their destination addresses. Unique local IPv6 unicast addresses (ULA) [10] can be used easily as MANET-local addresses. Global-scope Address An address used in MANET- and global-scope communications. The general format of IPv6 global-scope addresses is defined in IPv6 Address Architecture [11]. With this type of addresses, every node in hybrid MANET can access to another node in the MANET and to any host in the Internet. Hybrid MANET Address Autoconfiguration (HAA) The mechanism that configures MANET-local address and global-scope address to the nodes in a MANET. Because each node has the information about Internet gateway and next hop toward the gateway and Internet gateway maintains the information of MANET nodes, MANET-wide message broadcasting can be avoided. Internet Gateway (IG) The relaying node that provides Internet connectivity with the Park, et al., Expires April 22, 2007 [Page 4] Internet-Draft HAA October 2006 MANET nodes. IG also performs MANET-scope DAD by maintaining the list of its MANET nodes. In addition, IG allocates global-scope addresses to the nodes in the MANET. Default Node (DN) If a node has one or more HAA messages to be delivered to corresponding IG, the node direct all messages to `Default Node'. Only one of the node's neighbors can be a default node. This DN information is independent of any routing protocol. HAA Path If a node wants to exchange address autoconfiguration messages with its corresponding IG, the node sends the message to its default node, one of its one-hop neighbors. The next hop node then forwards this message to its default node repeatedly. As a result, the message is delivered to the IG. `HAA path' is the chain of default nodes among the IG and the nodes. HAA path is regarded as a tree path that has IG as its root. NDP Global Address Solicitation (GS) This is a newly defined message here to deliver each node's request for the allocation of global-scope address and MANET-scope DAD. NDP Global Address Advertisement (GA) This is a newly defined message here to deliver IG's response of each node's GS message. This contains the information about global-scope address to be allocated, or an error if necessary. Park, et al., Expires April 22, 2007 [Page 5] Internet-Draft HAA October 2006 3. IPv6 Address Autoconfiguration for Hybrid MANETs 3.1. Link-local DAD If a new node A joins a MANET, the node A makes its own link-local scope address, and then determines the duplication of the address. To detect address duplication, the node A broadcasts NDP `Neighbor Solicitation (NS)' message to all of 1-hop neighbors. If there is not any NDP `Neighbor Advertisement (NA)' message for a period of time, the node A uses the link-local scope address to get a global- scope address. If there are one or more NDP NA messages, the node A makes a new link-local scope address with a 64-bit long random value as a node ID according to IPv6 Stateless Address Autoconfiguration (SAA) [3]. Then the node A retries the link-local DAD by sending again a NDP NS message containing the new link-local address. 3.2. Default Node Selection If a newly joined node A fixes its link-local address, then it tries to get the information about the MANET's Internet gateway and default node. For this, the node A sends NDP `Router Solicitation (RS)' message to all of 1-hop neighbors. Each neighbor that receives the node A's RS message responses with NDP `Router Advertisement (RA)' message like a router of wired networks. In this RA message, a newly defined 'Default Node' option is attached. This option containes the addresses of Internet gateway and default node (e.g. the sender of this message), the path length measured in hop counts between the Internet gateway and the default node, and the lifetime of the information about default node. The node A then receives one or more RA messages. It selects one among these messages by searching the address of Internet gateway and hop counts. For example, if node B, C, and D send RA messages and the node B's RA message has the shortest hop counts to the corresponding IG, the node A selects the RA message generated by the node B. If there is no RA message during a period of T_WAIT_RA seconds, then the node A retries to send RS message. If there is still no RS Park, et al., Expires April 22, 2007 [Page 6] Internet-Draft HAA October 2006 message during N_RETRY_RS times retrial, then the node A stops HAA process. 3.3. HAA path If the node A gets the addresses of Internet gateway and default node, it participates in `HAA path'. At the begining of building a hybrid MANET, there is one node that is Internet gateway as infrastructure providing Internet connectivity. When there is not any user node except Internet gateway, a newly joined node does DAD with Internet gateway and gets the Internet gateway's address as a default node. As the following nodes are joined, each of nodes takes the former node's address as a default node. As a result, HAA path becomes a tree path that has Internet gateway as its root. The HAA path is used for the porpose of address autoconfiguration only. Each node's path toward Internet gateway is independent of any routing protocol, but this HAA path infomation can be used by a routing protocol if needed. 3.4. MANET-scope DAD and Global-scope Address Configuration Once a node A acquires the information about Internet gateway and default node, it can request the allocation of global-scope address by sending `Global Solicitation (GS)' message to Internet gateway. GS message is newly defined here as an extension to IPv6 NDP. This message has the `Node Address' option that contains the address of the node A. GS message is forwarded to the default node of each node repeatedly, along the HAA path. If the HAA path contains the loop by the mobility of some nodes, GS message will be silently dropped when its hop limit is decreased to 0. Then the node can detect the loop, and change or remove the invalid default node. If the loop is created in transient, the loop path is fixed before the GS message's hop limit becomes 0. If Internet gateway receives the NDP GS message, then it performs MANET-scope DAD by comparing the node A's address contained in GS message to the addresses from the list of registered nodes. If there is no duplicate address used by the node A's, then Internet gateway sends NDP `Global Advertisement (GA)' message. This message Park, et al., Expires April 22, 2007 [Page 7] Internet-Draft HAA October 2006 is defined as an extension to NDP like GS message. It contains the global-scope address to be allocated to the node A, and the length of prefix of its address. If the node A receives the message, then the node sets its address to the global-scope address. If an address duplication is detected, then Internet gateway sends the global-scope address allocation error message instead. This message uses the form of NDP GA message, but sets bit E to 1. If the node A receives that, it generates a new address and try again. Both GS and GA messages traverse along HAA path and are unicast messages. And message broadcasts are limited to 1-hop range, so the message overhead due to the HAA mechanism is relatively low. 3.5. Autoconfiguration without Internet Gateway A MANET can lose its gateway if all nodes of the MANET are moved out of the radio range of the gateway. By the absence of the gateway, allocation of global-scope address and its DAD procedure, and Internet connectivity become unavailable. If any node in the MANET cannot receive periodical GA messages from the gateway, it stops the use of its global-scope addresses and disconnects the sessions that were created using global-scope addresses previously. In contrary, the node keeps its own MANET-local address. Abitrary nodes can join to and leave from gateway-less MANET, so periodical DAD process for MANET-local address is required. But MANET-local addresses use the format of Unique local address (ULA), that is combined with pre- defined prefix for MANET and interface identifier built from EUI-64. Hence, optimistic DAD [12] can be used for the check of duplication of MANET-local addresses. Park, et al., Expires April 22, 2007 [Page 8] Internet-Draft HAA October 2006 4. HAA Message Formats 4.1. Default node option for RA message 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Hop Count | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Default Node Lifetime | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + + | | + Default Node Address + | | + + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + + | | + Internet Gateway Address + | | + + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type TBD Length 8-bit unsigned integer. The length of the option in unit of 8 octets. The value 0 is invalid. Hop Count 16-bit unsigned integer. The number of hops between Internet gateway and the sender of this message. Default Node Lifetime 32-bit unsigned integer and the length of time in seconds that this default node option is valid. The default value is TBD. Park, et al., Expires April 22, 2007 [Page 9] Internet-Draft HAA October 2006 Default Node Address An IPv6 address. This field contains the address of recommended node as a default node. Internet Gateway Address The IPv6 address of Internet gateway of the MANET in which the node is participated. 4.2. Global Address Solicitation message 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Code | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Options ... +-+-+-+-+-+-+-+-+-+-+-+- Type TBD Code TBD Checksum The ICMP checksum. Reserved This field is unused. 4.3. Node Address option for GS message 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | Park, et al., Expires April 22, 2007 [Page 10] Internet-Draft HAA October 2006 + + | | + Node Address + | | + + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type TBD Length 8-bit unsigned integer. The length of the option in unit of 8 octets. The value 0 is invalid. Reserved This field is unused. Identifier 32-bit unsigned integer. This field separates one request of global-scope address from the others. Internet gateway generates the response message for this message with the same identifier. The value is randomly generated. Node Address IPv6 link-local address of the sender. 4.4. Global Address Advertisement message 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Code | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | Gateway Lifetime | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Options ... +-+-+-+-+-+-+-+-+-+-+-+- Type TBD Park, et al., Expires April 22, 2007 [Page 11] Internet-Draft HAA October 2006 Code TBD Checksum The ICMP checksum. Reserved This field is unused. Gateway Lifetime 32-bit unsigned integer and the length of time in seconds that the global address contained in this message is valid. The default value is TBD. 4.5. Node confirm option for GA message 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length |E| Prefix Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + + | | + Node Address + | | + + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type TBD Length 8-bit unsigned integer. The length of the option in unit of 8 octets. The value 0 is invalid. E 1-bit field that represents if there is an error or not in the request. E bit is set to 1 if duplicate address is detected. Park, et al., Expires April 22, 2007 [Page 12] Internet-Draft HAA October 2006 Prefix Length 16-bit unsigned integer. The length of global-scope prefix. Identifier 32-bit unsigned integer. The field separates one request of global-scope address from the others. Internet gateway generates the response message for this message with same identifier. The value is randomly generated. Node Address IPv6 global-scope address to be allocated to the requester. Park, et al., Expires April 22, 2007 [Page 13] Internet-Draft HAA October 2006 5. Security Considerations This document does not describe any security facility of the hybrid address autoconfiguration. A malicious node may block the process by misdirecting some of the HAA messages, or make a newly joined node configure its address with invalid information. Park, et al., Expires April 22, 2007 [Page 14] Internet-Draft HAA October 2006 6. Revision of the Draft Version 2 of the draft has been revised as follows. - Section 2 `Terminology' was been updated. - Section 3.5 `Autoconfiguration without Internet Gateway' was been updated. Version 1 of the draft has been revised as follows. - This section was beed appended. - Section 3.5 `Autoconfiguration without Internet Gateway' was been appended. Park, et al., Expires April 22, 2007 [Page 15] Internet-Draft HAA October 2006 References [1] S. Bradner, "Key words for use in RFCs to Indicate Requirement Levels," RFC 2119, Internet Engineering Task Force, March 1997. [2] T. Narten, E. Nordmark, and W. Simpson. "Neighbor Discovery for IP Version 6 (IPv6)," RFC 2461, Internet Engineering Task Force, December 1998. [3] S. Thomson and T. Narten. "IPv6 Stateless Address Autoconfigura- tion," RFC 2462, Internet Engineering Task Force, December 1998. [4] R. Wakikawa, J. Malinen, C. Perkins, A. Nilsson, and A. Tuominen, "Internet Connectivity for Mobile Ad hoc networks," Internet Draft, draft-wakikawa-manet-globalv6-02.txt, November 2002. [5] C. Perkins, J. Malinen, R. Wakikawa, E. Belding-Royer, and Y. Sun, "IP Address Autoconfiguration for Ad Hoc Networks," Internet Draft, draft-ietf-manet-autoconf-01.txt, Nov. 2001, work in progress. [6] J. Jeong, "Ad Hoc IP Address Autoconfiguration," Internet Draft, draft-jeong-adhoc-ip-addr-autoconf-00.txt, Nov. 2003, work in progress. [7] S. Ruffino, P. Stupar, and T. Clausen, "Autoconfiguration in a MANET: connectivity scenarios and technical issues," Internet Draft, draft-ruffino-manet-autoconf-scenarios-00.txt, October 2004, work in progress. [8] S. Singh, J. Kim, C. Perkins, P. Ruiz, and T. Clausen, "Ad Hoc Net- work Autoconfiguration: Definition and Problem Statement," Internet Draft, draft-singh-autoconf-adp-00.txt, Feb. 2005, work in progress. [9] C. Bernardos and M. Calderon, "Survey of IP address autoconfigura- tion mechnisms for MANETs," Internet Draft, draft-bernardos-manet- autoconf-survey-00.txt, July 2005, work in progress. [10] R. Hinden and B. Haberman, "Unique Local IPv6 Unicast Addresses," RFC 4193, Internet Engineering Task Force, October 2005. Park, et al., Expires April 22, 2007 [Page 16] Internet-Draft HAA October 2006 [11] R. Hinden and S. Deering, "IP Version 6 Addressing Architecture," RFC 4291, Internet Engineering Task Force, February 2006. [12] N. Moore, "Optimistic Duplicate Address Detection (DAD) for IPv6," RFC 4429, Internet Engineering Task Force, April 2006. Author's Address Ilkyun Park Soongsil University, S. Korea Phone: +82 2 820 0904 Email: ikpark@dcn.ssu.ac.kr Younghan Kim Soongsil University, S. Korea Phone: +82 2 820 0904 Email: yhkim@dcn.ssu.ac.kr Namhi Kang Soongsil University, S. Korea Phone: +82 2 820 0904 Email: nalnal@dcn.ssu.ac.kr 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. Park, et al., Expires April 22, 2007 [Page 17] Internet-Draft HAA October 2006 Copies of IPR disclosures made to the IETF Secretariat and any assur- ances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf- ipr@ietf.org. 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, (THE IETF TRUST) 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. Park, et al., Expires April 22, 2007 [Page 18]