IETF MANET Working Group Shubhranshu. Singh Internet-Draft JH. Kim Expires: December 10, 2004 YG. Choi KL. kang YS. Roh SAMSUNG AIT June 11, 2004 Mobile multi-gateway support for IPv6 mobile ad hoc networks draft-singh-manet-mmg-00.txt Status of this Memo By submitting this Internet-Draft, I certify that any applicable patent or other IPR claims of which I am aware have been disclosed, and any of which I 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 December 10, 2004. Copyright Notice Copyright (C) The Internet Society (2004). All Rights Reserved. Abstract MANET (Mobile Ad-hoc NETwork) allows users to form a private wireless network, without existing centralized administrator that support multi-hop communication and low network establishment cost. Recently some interesting work has been published to allow manet node access to the Internet via internet gateway which is placed on the border of manet and the Internet. The Internet gateway has an important role Singh, et al. Expires December 10, 2004 [Page 1] Internet-Draft Mobile multi-gateway support in MANET June 2004 to support global connectivity. This document introduces the management of internet gateway, routing policy and load balancing for the scenario where multiple mobile gateways exist for an ad hoc network. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Limitations . . . . . . . . . . . . . . . . . . . . . . . . . 6 4. Protocol operation . . . . . . . . . . . . . . . . . . . . . . 7 4.1 Gateway selection . . . . . . . . . . . . . . . . . . . . 7 4.2 Routing policy . . . . . . . . . . . . . . . . . . . . . . 8 4.3 Load balancing . . . . . . . . . . . . . . . . . . . . . . 9 5. Security Considerations . . . . . . . . . . . . . . . . . . . 11 6. Normative References . . . . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 11 Intellectual Property and Copyright Statements . . . . . . . . 13 Singh, et al. Expires December 10, 2004 [Page 2] Internet-Draft Mobile multi-gateway support in MANET June 2004 1. Introduction There are several routing protocols developed for ad hoc networks. They typically provide solution for route discovery and maintenance for the nodes within the manet. Nodes often need global connectivity to communicate with the Internet. Wakikawa[1] provides a method for manet node to acquire a global prefix from the gateway as well as how this node can communicate with the Internet. Use of fixed internet gateway is not suitable for ad hoc network whose basic concept is infrastructureless and anywhere network formed by nodes having random mobility. Hence in this draft we allow mobile ad hoc node to act as internet gateway thus removing any service range limitation and making very flexible as against when fixed internet gateway is used. Also, it removes any concern about the use of proactive or reactive routing protocols. There are some signal exchanges between the internet gateway and manet node for locating the gateway. In addition,The traffic between manet node and the Internet must travel through the same internet gateway in case of single gateway scenario.Simultaneous use of internet gateway by several manet nodes results in heavy traffic congestion around the gateway node. Thus there is a need to offload the gateway. Also, Use of single gateway has the drawback of single point of failure. All these problems can be solved by using multiple gateways for a particular manet. The multiple internet gateway scenario is easily made with mobile node internet gateway. This document specifies the method for multiple gateway selection and routing policy that can be used to forward packets between the Internet and ad hoc network. Figure 1 shows the multiple gateways scenario. Singh, et al. Expires December 10, 2004 [Page 3] Internet-Draft Mobile multi-gateway support in MANET June 2004 ------------ | INTERNET | ------------ | | | | ---------- | Access | ----------- | Router | ------------- | ---------- | | : | | : | | : | ------------ : ------------ | Internet| : | Internet| | Gateway 1| ....... | Gateway n| ------------ ------------ | | | | | | ----------------------------------------------------- | | | MANET | | | ----------------------------------------------------- Fig. 1 MANET topology with multi-gateway Singh, et al. Expires December 10, 2004 [Page 4] Internet-Draft Mobile multi-gateway support in MANET June 2004 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]. The following terminology and abbreviations are used in this document. Mobile Internet gateway - Mobile device located at the edge of the manet and provides Internet connectivity to the manet nodes. They are part of manet as well as the Internet. Default Internet gateway - The Internet gateway that uses the default route for traffic forwarding between manet and the Internet. It need not use tunneling or routing header to route packets between the Internet and manet. Candidate Internet gateway - Internet gateways other than the default gateway are referred to as candidate gateways. Proxy routing header - The routing header that candidate internet gateway may use for forwarding manet node packets to the Internet. Internet node - A node located on the Internet. Manet node - A node located inside the manet. Global address - A nodeí¯s IPv6 address which is used for communication with the Internet node. Singh, et al. Expires December 10, 2004 [Page 5] Internet-Draft Mobile multi-gateway support in MANET June 2004 3. Limitations For convenience and simplicity we assume in this draft that all manet nodes within a particular ad hoc network use the same global IPv6 prefix. How manet nodes acquire the same IPv6 prefix from the access router is out of scope of this document. Singh, et al. Expires December 10, 2004 [Page 6] Internet-Draft Mobile multi-gateway support in MANET June 2004 4. Protocol operation This section describes our protocol operation in detail. 4.1 Gateway selection Any manet node that is one hop away from the Access Router, AR can configure itself as gateway. Such nodes can receive router advertisement messages periodically broadcasted by access router. At any point of time there can be one default gateway and one or more candidate gateways. In the absence of any default gateway, the node configuring as a gateway should operate as default gateway. If the default gateway is already present in the manet then the node should configure itself as candidate gateway. Only the default gateway periodically sends modified router advertisement message. Default gateway also sends modified router advertisement message in response to modified router solicitation message. Modified router solicitation message format is shown in figure2 and modified router advertisement message format is shown in figure 3. Modified router solicitation and advertisement packet formats are same as defined in [5] except the use of M and N bits respectively (these formats are exactly same as used in [1]). 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |M| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Options ... +-+-+-+-+-+-+-+-+-+-+-+- Fig. 2 Modified RS Manet router solicitation flag (M) A 1-bit manet router solicitation flag. When set it indicates that the router solicitation message can be sent over a multi-hop network. The internet gateway must not forward this message to the internet node. Reserved Reduced from a 32-bit field to 31-bit field to account for the addition of manet router solicitation (M) flag. Singh, et al. Expires December 10, 2004 [Page 7] Internet-Draft Mobile multi-gateway support in MANET June 2004 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Cur Hop Limit |M|O|N| Reserved | Router Lifetime | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reachable Time | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Retrans Timer | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Options ... +-+-+-+-+-+-+-+-+-+-+-+- Fig. 3 Modified RA Manet router advertisement flag (N) 1-bit manet router advertisement flag. When set indicates that this message is only for manet nodes and can be sent over multiple hop manet nodes. Internet gateways must not forward this message to the Internet node. A node may learn about the presence or absence of another gateway in the manet if: - It does not receive any RA message from the gateway with N flag set. The waiting time for RA should be at least the time indicated by the í«new advertisement interval optioní¯. This router advertisement interval option indicates the interval at which the default gateway advertises unsolicited router advertisement [6]. - It sends gateway solicitation message or tests for neighbor reachability, as explained in [5] and fails. In the absence of any received RA message, a candidate gateway should wait for random interval of time before configuring itself as default gateway. This will prevent more than one gateway to configure itself as default gateway at the same time. While operating as internet gateway, the node should send gateway discovery reply messages. 4.2 Routing policy Default gateway and candidate gateway routes packets between the Internet and manet based on its own routing policy. In this document we introduce proxy routing header and tunneling mechanism. Proxy routing header and tunneling mechanism are used by candidate internet gateways as they can not use the longest prefix matching routing. We assume that the default gateway as well as the candidate gateways Singh, et al. Expires December 10, 2004 [Page 8] Internet-Draft Mobile multi-gateway support in MANET June 2004 uses the same global IPv6 prefix. How to receive same prefix from the access router is out of scope of this document. Use of multiple prefixes results in serious flooding problem mainly due to periodic RA message advertisement by each gateway with different prefix. Also, if multiple prefixes are used then IPv6 manet node may attempt to send frequent binding update message because each time it receives router advertisement message with different prefix it assumes that it has joined another network even though it has only changed its location within the same manet. Default gateway can route traffic originating from manet node and whose destination is internet node using default route while the candidate gateways should route such traffic either using proxy routing header or tunneling mechanism. In proxy routing header destination address of IPv6 header is set to the Internet access router address while final destination address set to internet node address and original source address set to routing header. Proxy routing header indicates to internet node that the packet travel via candidate internet gateway and access router. In response to this received packet, internet node must use candidate internet gateway and original source address in the routing header. If manet node uses tunneling mechanism, candidate internet gateways encapsulate packets to the internet node. Tunneling header has source address as candidate internet gateway and destination address as internet node. The internet node decapsulates the packet and replies with tunneling header with source address as internet nodeí¯s address and destination address as candidate internet gatewayí¯s address. 4.3 Load balancing For better traffic load sharing among each other, internet gateways may use the traffic information option shown in figure 4. This option is carried by the router advertisement message sent by internet gateway. Traffic information field indicates the number of active routes originating from a particular gateway. These active routes include routes using proxy routing header, tunneling as well as default routes. On receipt of solicited or unsolicited router advertisement message carrying this option, manet node learns about the traffic characteristics of the gateway and accordingly decides to use it or opt for another gateway for forwarding traffic to the internet node. Singh, et al. Expires December 10, 2004 [Page 9] Internet-Draft Mobile multi-gateway support in MANET June 2004 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 | traffic information | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Fig. 4 Traffic information option Singh, et al. Expires December 10, 2004 [Page 10] Internet-Draft Mobile multi-gateway support in MANET June 2004 5. Security Considerations This document does not specify any specific security measure. We need more consideration for the secure tunneling and use of routing header. These mechanisms should consider all the security measures as taken by IPv6 networks as well as manet specific environment. We couldní¯t mention about secure intra manet communication as at present there in no extended security consideration for the manet. 6. References [1] Ryuji Wakikawa et. el. Global connectivity for IPv6 Mobile Ad Hoc Networks, IETF í—draft-wakikawa-manet-globalv6-03.txtí˜ [2] Pekka Pekken et. el. IPv6 addressing in a heterogeneous MANET-network, IETFí—draft-paakkonen-addressing-htr-manet-00.txtí˜ [3] C. Perkins et. el. IETF RFC: 3561, í—Ad hoc On Demand Distance Vector (AODV) Routingí˜ [4] Kilian Weniger , Martina Zitterbart, Institute of Telematics, University of Karlsruhe, Germany: í—IPv6 Autoconfiguration in Large Scale Mobile Ad-Hoc Networksí˜ [5] IETF RFC 2461, í— Neighbor Discovery for IP version 6 (IPv6)í˜ [6] IETF draft, í—draft-ietf-mobileip-ipv6-24.txt í—: í—Mobility Support in IPv6í˜ [7] C. Perkins, E. Royer and S. Das. Ad hoc on demand distance vector routing for IP version 6 (work in progress). [8] S. Deering and R. Hinden. Internet protocol, version 6 (ipv6) specification. Request for comments (proposed standard) 1883, Internet engineering task force, December 1995 [9] A. Conta and S. Deering. Internet control message protocol (ICMPv6) for the Internet protocol version 6 (ipv6) specification. Request for comment (draft standard) 2463. Internet Engineering task force, December 1998 Authors' Addresses Shubhranshu Singh SAMSUNG Advanced Institute of Technology i-Networking Laboratory San 14-1, Nongseo-ri, Giheung-eup Yongin-si, Gyeonggi-do 449-712 KOREA Phone: +82 31 280 9569 EMail: shubhranshu@samsung.com Jae-Hoon Kim SAMSUNG Advanced Institute of Technology i-Networking Laboratory 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 December 10, 2004 [Page 11] Internet-Draft Mobile multi-gateway support in MANET June 2004 YoungGon Choi SAMSUNG Advanced Institute of Technology i-Networking Laboratory San 14-1, Nongseo-ri, Giheung-eup Yongin-si, Gyeonggi-do 449-712 KOREA Phone: +82 31 280 9531 EMail: ygchoi@samsung.com Kyunglim Kang SAMSUNG Advanced Institute of Technology i-Networking Laboratory San 14-1, Nongseo-ri, Giheung-eup Yongin-si, Gyeonggi-do 449-712 KOREA Phone: +82 31 280 9532 EMail: klkang@samsung.com Yongsung Roh SAMSUNG Advanced Institute of Technology i-Networking Laboratory San 14-1, Nongseo-ri, Giheung-eup Yongin-si, Gyeonggi-do 449-712 KOREA Phone: +82 31 280 9532 EMail: yongsung.roh@samsung.com Singh, et al. Expires December 10, 2004 [Page 12] Internet-Draft Mobile multi-gateway support in MANET June 2004 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. Copies of IPR disclosures made to the IETF Secretariat and any assurances 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 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 (2004). 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. Singh, et al. Expires December 10, 2004 [Page 13]