Network Working Group Y-G. Hong Internet-Draft J-C. Lee Expires: April 17, 2006 J-S. Park H-J. Kim ETRI October 16, 2005 Analysis of multiple interfaces in a Mobile Node draft-hong-multipleif-mn-pb-statement-00 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 17, 2006. Copyright Notice Copyright (C) The Internet Society (2005). Abstract This document is an analysis of multiple interfaces in a mobile node using Mobile IPv6 or a mobile router using NEMO Basic Support. The current Mobile IPv6 and NEMO Basic Support are suitable for a single network interface. When a mobile node or a mobile router has multiple interfaces, the current Mobile IPv6 and NEMO Basic Support cannot directly be used for them. In this document, we describe some Hong, et al. Expires April 17, 2006 [Page 1] Internet-Draft Analysis of multiple interfaces in a MN October 2005 problems for a mobile node which has multiple network interfaces when the mobile node is using Mobile IPv6 as an aspect of a node. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Problem Statements . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Mobile IPv6-specific Issues . . . . . . . . . . . . . . . 4 2.2. General Network Issues . . . . . . . . . . . . . . . . . . 4 2.3. Considerations for Heterogeneous Environments . . . . . . 6 3. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 7 4. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.1. Normative References . . . . . . . . . . . . . . . . . . . 8 4.2. Informative References . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 Intellectual Property and Copyright Statements . . . . . . . . . . 10 Hong, et al. Expires April 17, 2006 [Page 2] Internet-Draft Analysis of multiple interfaces in a MN October 2005 1. Introduction In future ubiquitous networks, many services and many access technologies are expected to be interworked and harmonized for better services. To do so, a mobile node must have different access technologies and different network interfaces for each access technology [3]. Mobile IPv6 [1] and NEMO Basic Support [2] can solve the problem of the change of IPv6 network address when a mobile node or a mobile router moves. But these protocols are developed for a mobile node with a single network interface and a mobile router with a single egress network interface. We can not directly use Mobile IPv6 for a mobile node with multiple network interfaces [4,5]. This document describes the problems of multiple interfaces in a mobile node as an aspect of a node. Hong, et al. Expires April 17, 2006 [Page 3] Internet-Draft Analysis of multiple interfaces in a MN October 2005 2. Problem Statements 2.1. Mobile IPv6-specific Issues In Mobile IPv6, a mobile node knows its network movement by comparing the prefix information, which is included in the latest arrived Router Advertisement messages, with the prefix information, which is stored in locally or using other ways [6]. The operations required for handover such as Binding update or Binding Acknowledgement happens only after a mobile node determines the movement to different networks. To determine network movement, a mobile node carefully observes the received Router Advertisement messages from routers through one specific network interface. Usually, the specific network interface is selected when Mobile IPv6 module starts. In this case, the mobile node is focusing on only that network interface to detect movement. Router Advertisement messages that came from other network interfaces do not affect the operations of the mobile node (determination of movement detection) if the mobile node has multiple network interfaces and it observe only one specific network interface. When we apply Mobile IPv6 and the implementation of Mobile IPv6 code (HUT MIPL) [7] to a mobile node which has multiple network interfaces, we must consider Router Advertisement messages which are delivered through all network interfaces, not only the specific network interface, which is selected when Mobile IPv6 module start. When a mobile node has multiple network interfaces, a mobile node must have the ability to look at all Router Advertisement messages from different network interfaces because Router Advertisement messages may be delivered from different network interfaces. 2.2. General Network Issues The primary purpose of Mobile IPv6 or NEMO Basic Support is to maintain a communication session even though the IPv6 address of a mobile node or a mobile router has changed when the mobile node or the mobile router moves. As an application layer's view or socket layer's view, the address of a mobile node (Home Address) is not changed nevertheless the Care of Address is changed. This rule must also be applied when multiple network interfaces are used in a mobile node. The problem of multiple network interfaces in a mobile node is the relation between a destination address and a network interface. In the following case, we assume a mobile node with two network interfaces I1 and I2 of different access technologies. Each interface is configured with a global IPv6 address, respectively IP1 Hong, et al. Expires April 17, 2006 [Page 4] Internet-Draft Analysis of multiple interfaces in a MN October 2005 and IP2, and the address of a correspondent node is IP3. _________ | CN | |_________| | IP3 /|\ +------------------+ +------------------+ | Network 1 (N1) | | Network 2 (N2) | | | | | +------------------+ +------------------| Interface 1 (I1) \|/ \|/ Interface 2 (I2) IP1 | | IP2 |_________| | MN | |_________| Figure 1. A mobile node with two interfaces | Location |(Source Address, |Relation btw a Destination| |(Used I/F)| Destination Address) | Addr. and a network I/F | |-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-| | N1 (I1) | (IP1, IP3) | IP3 -> I1 | | N2 (I2) | (IP2, IP3) | IP3 -> ? | Figure 2. Relation between destination address and network interfaces The mobile node uses Mobile IPv6 when it moves between networks. Before moving, when the mobile node uses (I1, IP1) and sends packets to a correspondent node, the source address and destination address of packets is (IP1, IP3) and the used network interface is I1. If the mobile node moves other network N2, and then the mobile node uses (I2, IP2) and the used network interface is I2. Before moving, the destination address (IP3) of the correspondent node is mapped to a network interface I1. After moving, when an application tries to send packets to the correspondent node, it continually tries to use a network interface I1 if the relation of destination address IP3 and network interface I1 is not updated properly. If this situation happens, even though, the network interface is changed to I2, packets are delivered to I1. The communication sessions will be disrupted. To solve this problem, a mobile node must update the relation between a destination address and a network interface when it changes a network interface. Hong, et al. Expires April 17, 2006 [Page 5] Internet-Draft Analysis of multiple interfaces in a MN October 2005 2.3. Considerations for Heterogeneous Environments If a mobile node moves between networks with a single network interface, the change may be only a network address. Because the mobile node has an access technology of the single network interface, it doesn't need to consider other aspects such as the change of access technologies and IP version. If a mobile node moves between networks with multiple network interfaces, other changes may happen. If a mobile node has heterogeneous network interfaces (one is a WLAN interface and the other is a CDMA interface), changes include the network address, network interface and access technologies of the selected network interface after moving. Currently in Korea, we can use IPv6 based WLAN service but it is impossible to use IPv6 based CDMA service. The deployment of IPv6 based CDMA service will be done sooner or later. Until the deployment of IPv6 based CDMA service occur, if we want to use Mobile IPv6 or NEMO Basic Support with a CDMA network interface, we must consider how to use Mobile IPv6 or NEMO Basic Support in IPv4 based CDMA network. Hong, et al. Expires April 17, 2006 [Page 6] Internet-Draft Analysis of multiple interfaces in a MN October 2005 3. Conclusions Multihoming of a mobile node or a mobile router is an important issue as described in [3]. When a mobile node has multiple interfaces, the mobile node can use heterogeneous network interfaces and it can provide ubiquitous access. In this document, we showed the issues when a mobile node or a mobile router has multiple network interfaces as an aspect of a node. If a mobile node and a mobile router have multiple network interfaces, the mobile node and the mobile router must have the ability to look at all Router Advertisement messages from different network interfaces. Also the mobile node and the mobile router must update dynamically the relation of a destination address of a correspondent node and a network interface after the change of a network interface. Because the mobile node may use heterogeneous access technologies, some access networks of a selected network interface do not support IPv6. In this case we must consider how to support Mobile IPv6 and NEMO Basic Support in IPv4 based networks. Hong, et al. Expires April 17, 2006 [Page 7] Internet-Draft Analysis of multiple interfaces in a MN October 2005 4. References 4.1. Normative References [1] Johnson, D., Perkins, C. and J. Arkko, "Mobility Support in IPv6", RFC 3775, June 2004. [2] Devarapalli, V., Wakikawa, R., Petrescu, A. and Thubert, P., "Network Mobility (NEMO) Basic Support Protocol", RFC 3963, January 2005. 4.2. Informative References [3] Ernst, T., Montavont, N., Wakikawa, R., Paik, E., and K. Kuladinithi, "Goals and Benefits of Multihoming", draft-ernst-generic-goals-and-benefits-01 (work in progress), February 2005. [4] Montavont, N., Wakikawa, R., Ernst, T., Ng, C-W., and K. Kuladinithi, "Analysis of Multihoming in Mobile IPv6", draft-montavont-mobileip-multihoming-pb-statement-04 (work in progress), June 2005. [5] Montavont, N., Noel, T. and Kassi-Lahlou, M., "Mobile IPv6 for multiple interfaces (MMI)", draft-montavont-mip6-mmi- 02.txt (work in progress), July 2005. [6] Choi, J. and Nordmark, E., "DNA with unmodified routers: Prefix list based approach", draft-ietf-dna-cpl-01.txt (work in progress), April 2005. [7] MIPL Mobile IPv6 for Linux, http://www.mobile-ipv6.org Hong, et al. Expires April 17, 2006 [Page 8] Internet-Draft Analysis of multiple interfaces in a MN October 2005 Authors' Addresses Yong-Geun Hong ETRI 161 Gajeong-dong Yuseong-gu Daejeon, 305-350 Korea Phone: +82 42 860 6557 Email: yghong@etri.re.kr Joo-Chul Lee ETRI 161 Gajeong-dong Yuseong-gu Daejeon, 305-350 Korea Phone: +82 42 860 1021 Email: rune@etri.re.kr Jung-Soo Park ETRI 161 Gajeong-dong Yuseong-gu Daejeon, 305-350 Korea Phone: +82 42 860 6514 Email: pjs@etri.re.kr Hyoung-Jun Kim ETRI 161 Gajeong-dong Yuseong-gu Daejeon, 305-350 Korea Phone: +82 42 860 6576 Email: khj@etri.re.kr Hong, et al. Expires April 17, 2006 [Page 9] Internet-Draft Analysis of multiple interfaces in a MN October 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. 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. 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Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Hong, et al. Expires April 17, 2006 [Page 10]