Network Working Group Y. Hong Internet-Draft ETRI Intended status: Informational J. Youn Expires: September 2, 2009 DONG-EUI Univ. March 1, 2009 Analysis and scenarios of multiple interfaces in a host draft-hong-mif-analysis-scenario-00 Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and 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 September 2, 2009. Copyright Notice Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Abstract This document is an analysis of multiple interfaces in a host and description of scenarios of multiple interfaces with the respect of Hong & Youn Expires September 2, 2009 [Page 1] Internet-Draft mif analysis & scenario March 2009 TCP/IP layer. The current TCP/IP mechanism and networking methods are suitable for a single network interface. When a host has multiple interfaces, the current TCP/IP mechanism and networking methods cannot directly be used for them. In this document, we describe some problems for a host which has multiple network interfaces as an aspect of host's operations and some usage scenarios of multiple interfaces in a host. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Problem Statements . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Relation between network interface and destination address . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2. Considerations for heterogeneous environments with different IP version . . . . . . . . . . . . . . . . . . . 5 3. Scenarios of host with multiple interfaces . . . . . . . . . . 5 3.1. Multiple interfaces but none layer do not support . . . . 5 3.2. Multiple interfaces and only network layer support . . . . 6 3.3. Multiple interfaces and network layer and transport layer support . . . . . . . . . . . . . . . . . . . . . . 7 3.4. Multiple interfaces and all layer support . . . . . . . . 8 3.5. Multiple interfaces and specific layer support . . . . . . 8 4. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 9 5. Security Considerations . . . . . . . . . . . . . . . . . . . 9 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 7.1. Normative References . . . . . . . . . . . . . . . . . . . 10 7.2. Informative References . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 Hong & Youn Expires September 2, 2009 [Page 2] Internet-Draft mif analysis & scenario March 2009 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 host must have different access technologies and different network interfaces for each access technology. Mobile IPv6 [RFC3775][1] and NEMO Basic Support [RFC3963] [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. Due to multiple interfaces, there are many things to be considers such as multiple CoA, multiple HoA, and multiple HA. We cannot directly use basic Mobile IPv6 for a mobile node with multiple network interfaces. IETF MEXT working group are targeting to solve these problems and have developed many solutions. If a host has multiple interfaces, this situation influences not only mobility issues (e.g., extending Mobile IPv6/NEMO Basic Support) but also general networking operations and TCP/IP mechanism [I-D.blanchet-mif-problem-statement][3] [I-D.hui-ip-multiple- connections-ps][4]. This document describes the problems of multiple interfaces in a host as an aspect of host's operations. Because of the change of network interface in communication, it needs the proper update between destination address and network interfaces, and consideration for heterogeneous environment with different IP version. And this document describes the scenarios of multiple interfaces in a host with the respect of TCP/IP stack. Because of the difference of overhead and cost of each layer to support multiple interfaces, there may be various scenarios of multiple interfaces in a host to use. 2. Problem Statements 2.1. Relation between network interface and destination address The problem of multiple network interfaces in a host is the relation between a destination address and a network interface. In the following case, we assume a host with two network interfaces I1 and I2 of different access technologies. Each interface is configured with a global IPv6 address, respectively IP1 and IP2, and the address of a correspondent node is IP3. Hong & Youn Expires September 2, 2009 [Page 3] Internet-Draft mif analysis & scenario March 2009 _________ | CN | |_________| | IP3 /|\ +------------------+ +------------------+ | Network 1 (N1) | | Network 2 (N2) | | | | | +------------------+ +------------------| Interface 1 (I1) \|/ \|/ Interface 2 (I2) IP1 | | IP2 |_________| | host | |_________| Figure 1: A host 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 -> ? | +-------------+-----------------------+-----------------------------+ Table 1: Relation between destination address and network interfaces The host may change its interface for communication with a correspondent node due to movement or change of network environments. Before the change of network interface, when the host 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 host moves other network N2, and then the host uses (I2, IP2) and the used network interface is I2. Before the change of network interface, the destination address (IP3) of the correspondent node is mapped to a network interface I1. However after the change of network interface, 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 properly updated. If this situation happens, even though, the network interface is changed to I2, packets are delivered to I1 at the link layer or L2 layer. The communication sessions will be disrupted. To solve this problem, a host must properly update the relation between a destination address and a network interface when it changes Hong & Youn Expires September 2, 2009 [Page 4] Internet-Draft mif analysis & scenario March 2009 a network interface. 2.2. Considerations for heterogeneous environments with different IP version If a host moves between networks with a single network interface or access technology, the change may be only a network address. Because the host has an access technology of the single network interface, it doesn't need to consider other aspects such as the change of access technology and IP version. If a host moves between networks with multiple network interfaces or access technologies, other changes may happen. If a host has multiple network interfaces (one is a WLAN interface and the other is a CDMA interface) in heterogeneous environments, changes include the network address, network interface and access technologies of the selected network interface after moving. Particularly, the main issue is the network address. 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, if we want to use IPv6 service with a CDMA network interface, we must consider how to use IPv6 service in IPv4 based CDMA network. 3. Scenarios of host with multiple interfaces If a host has multiple interfaces, it influences not only PHY/MAC layer but also other layer such as network layer, transport layer, and application layer (and a user). As the deployment of multiple interfaces to a host, there may be various scenarios of the usage of host with multiple interfaces. At the beginning time, even though a host adapts multiple interfaces, other layers could not have capability to support multiple interfaces. Also, a user who uses a host with multiple interfaces could not acknowledge the existence of multiple interfaces. As the deployment of multiple interfaces, other layer could have capability to support multiple interfaces. But, in some cases, a specific layer could not have capability to support multiple interfaces in a host. 3.1. Multiple interfaces but none layer do not support At the beginning time, a host adapts multiple interfaces but other layers do not support multiple interfaces. (Other layers are not aware of the existence of multiple interfaces.) Because the overhead and cost of modification of original network layer, transport layer, and application layer, it is difficult to modify other layer all at once to support multiple interfaces in a host. For specific Hong & Youn Expires September 2, 2009 [Page 5] Internet-Draft mif analysis & scenario March 2009 applications and/or specific OS, it could be difficult to modify them to support multiple interfaces. In this case, the connection manager must provide method to use multiple interfaces even though other layers do not support multiple interfaces. There are typical works to support this case [5], [6]. +-------------------------------+ | Original Applications | |-------------------------------| | Original TCP/UDP/SCTP/DCCP | |-------------------------------| | Original IPv6/IPv4 | |-------------------------------| | +-------------------+ | | Connection Manager| | +-------------------+ | | | +------------+ +------------+ | | | Interface 1| | Interface n| | | | (I1) | | (In) | | | +------------+ +------------+ | +-------------------------------+ Figure 2: A host with multiple interfaces when other layer does not support 3.2. Multiple interfaces and only network layer support As time goes on, a host adapts multiple interfaces and network layer support multiple interfaces. (transport layer, application layer, and user are not aware of the existence of multiple interfaces.) The Mobile IPv6 which is extended to support multiple interfaces could be in this case [7]. In this case, the connection manager must provide method to use multiple interfaces with the help of the network layer. Hong & Youn Expires September 2, 2009 [Page 6] Internet-Draft mif analysis & scenario March 2009 +-------------------------------+ | Original Applications | |-------------------------------| | Original TCP/UDP/SCTP/DCCP | |-------------------------------| | Modified | | IPv6/IPv4 +-------------------+ |---------------------| Connection Manager| | +-------------------+ | | | +------------+ +------------+ | | | Interface 1| | Interface n| | | | (I1) | | (In) | | | +------------+ +------------+ | +-------------------------------+ Figure 3: A host with multiple interfaces when network layer supports 3.3. Multiple interfaces and network layer and transport layer support In this case, a host adapts multiple interfaces and network layer and transport layer support multiple interfaces. (application layer, and user are not aware of the existence of multiple interfaces.) Until now, it seems that existing TCP/UDP could not have the capability to support multiple interfaces. And it seems that SCTP could have the capability to support multiple interfaces but it needs to be more enhanced. In this case, the connection manager must provide the method to use multiple interfaces with the help of the network layer and the transport layer. +-------------------------------+ | Original Applications | |-------------------------------| | Modified | | TCP/UDP/SCTP/DCCP +-------------------+ |---------------------| | | Modified | Connection Manager| | IPv6/IPv4 | | |---------------------| | | +-------------------+ | +------------+ +------------+ | | | Interface 1| | Interface n| | | | (I1) | | (In) | | | +------------+ +------------+ | +-------------------------------+ Figure 4: A host with multiple interfaces when network layer and transport layer support Hong & Youn Expires September 2, 2009 [Page 7] Internet-Draft mif analysis & scenario March 2009 3.4. Multiple interfaces and all layer support In this case, a host adapts multiple interfaces and all layers including network layer, transport layer, and application layer support multiple interfaces. And all layers are aware of the existence of multiple interfaces. In this case, the connection manager must provide the method to use multiple interfaces with the help of the network layer, the transport layer, and the application layer. +-------------------------------+ | Modified +-------------------+ | Applications | | |---------------------| | | Modified | | | TCP/UDP/SCTP/DCCP | Connection Manager| |---------------------| | | Modified | | | IPv6/IPv4 | | |---------------------| | | +-------------------+ | +------------+ +------------+ | | | Interface 1| | Interface n| | | | (I1) | | (In) | | | +------------+ +------------+ | +-------------------------------+ Figure 5: A host with multiple interfaces when all layer support 3.5. Multiple interfaces and specific layer support In this case, a host adapts multiple interfaces and one or two specific layers support multiple interfaces. Because it seems that it is difficult to modify network layer and transport layer to support multiple interfaces (typically, network layer and transport layer are in kernel space and application layer is in user space in Linux OS), application layer could be easily modified to support multiple interfaces. In this case, the connection manager must provide the method to support multiple interfaces with the help of specific layer even though intermediate layer does not support it. Hong & Youn Expires September 2, 2009 [Page 8] Internet-Draft mif analysis & scenario March 2009 +-------------------------------+ | Modified --+-+ +-------------------+ | Applications | +--| Connection Manager| |-------------------------------| | +-------------------+ | Original TCP/UDP/SCTP/DCCP | | |-------------------------------| | | Original IPv6/IPv4 | | |-------------------------------| | | --+-+ | +------------+ +------------+ | | | Interface 1| | Interface n| | | | (I1) | | (In) | | | +------------+ +------------+ | +-------------------------------+ Figure 6: A host with multiple interfaces when application layer supports 4. Conclusions When a host has multiple interfaces, the host can use heterogeneous network interfaces and it can provide ubiquitous access. In this document, we showed the issues when a host has multiple network interfaces as an aspect of host's operations. If a host is able to use multiple network interfaces, the host 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 host may use different access technologies in heterogeneous networks with different IP version, some access networks of a selected network interface do not support IPv6. In this case we must consider how to support IPv6 service in IPv4 based networks. Because of the difference of deployment of multiple interfaces in a host, there may be various scenarios of multiple interfaces in a host to use. We should clarify considerations and issues of each scenario for further study. 5. Security Considerations If a host has multiple interfaces and does not properly update the relation between network interfaces and destination address, the communication may disrupt. 6. IANA Considerations This document has no actions for IANA. Hong & Youn Expires September 2, 2009 [Page 9] Internet-Draft mif analysis & scenario March 2009 7. References 7.1. 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 P. Thubert, "Network Mobility (NEMO) Basic Support Protocol", RFC 3963, January 2005. 7.2. Informative References [3] Blanchet, M., "Multiple Interfaces Problem Statement, draft-blanchet-mif-problem-statement-00 (work in progress)", December 2009. [4] Hui, M. and H. Deng, "Problem Statement and Requirement of Simple IP Multi-homing of the Host, draft-hui-ip-multiple-connections-ps-01 (work in progress)", November 2008. [5] Hong, Y. and J. Youn, "Virtual network interface model for multiple network interfaces in a host draft-hong-mif-virtual-interface-00 (work in progress)", February 2009. [6] "SHISA, An implementation of Mobile IPv6", . [7] Wakikawa, R., Devarapalli, V., Ernst, T., and K. Nagami, "Multiple Care-of Addresses Registration, draft-ietf-monami6-multiplecoa-11 (work in progress)", January 2009. Authors' Addresses Yong-Geun Hong ETRI 161 Gajeong-Dong Yuseung-Gu Daejeon, 305-700 Korea Phone: +82 42 860 6557 Email: yonggeun.hong@gmail.com Hong & Youn Expires September 2, 2009 [Page 10] Internet-Draft mif analysis & scenario March 2009 Joo-Sang Youn DONG-EUI Univ. Busan, Korea Phone: +82 51 890 1993 Email: joosang.youn@gmail.com Hong & Youn Expires September 2, 2009 [Page 11]