Internet Area M. Hui Internet-Draft H. Deng Intended status: Informational China Mobile Expires: January 8, 2009 July 7, 2008 Problem Statement and Requirement of Simple IP Multi-homing of the Host draft-hui-ip-multiple-connections-ps-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 January 8, 2009. Hui & Deng Expires January 8, 2009 [Page 1] Internet-Draft IP Multi-Connect July 2008 Abstract This document discusses current problems with simple IP multi-homing. In order to have deep understanding of the issue, the document also analyzes related works in IETF. In the end gives the requirements of the simple IP multi-homing in concern of technical implements. Simple IP multi-homing focuses on simultaneous multiple IP connections of the host. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Problem statements of Simple IP Multi-homing . . . . . . . . . 4 2.1. Default Gateway . . . . . . . . . . . . . . . . . . . . . 4 2.2. Metric Rules . . . . . . . . . . . . . . . . . . . . . . . 4 2.3. Weak and Strong Host Model . . . . . . . . . . . . . . . . 5 3. Analysis of Related Work in IETF . . . . . . . . . . . . . . . 6 3.1. Multi6 . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3.2. Shim6 . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3.3. Monami6 . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.4. Proxy Mobile IPv6 . . . . . . . . . . . . . . . . . . . . 7 4. Requirements for Simple IP Multi-homing . . . . . . . . . . . 8 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 6. Security Considerations . . . . . . . . . . . . . . . . . . . 10 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 7.1. Normative References . . . . . . . . . . . . . . . . . . . 11 7.2. Informative References . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 Intellectual Property and Copyright Statements . . . . . . . . . . 13 Hui & Deng Expires January 8, 2009 [Page 2] Internet-Draft IP Multi-Connect July 2008 1. Introduction Simple IP Multi-homing means the host connects to more than one physical network through different network interfaces, and assigns different network flows to each interface, and ensure all the interfaces can deliver the flow simultaneously. Simple IP Multi-homing is a necessary part of daily life, i.e., you must connect with the VPN by your Ethernet interface when you are at work, at the same time you want to watch the stock market, which is forbidden in the VPN, so you need another connection to the GPRS network simultaneously. Current host operating systems allow one default connection at once. If there are multiple connections of the host, all the flows will go to the default gateway, although you can find several !o0.0.0.0!+/- routs in the host route table. One default gateway guarantees the host always has one exit to the network, but cause the multiple connections be impossible. The most convenient way to make the host work under several networks at the same time is to add specific static route in the host route table, so that certain flow can use the assigned interface while others use the default one, but it is too hard for the ordinary users to handle it. Hui & Deng Expires January 8, 2009 [Page 3] Internet-Draft IP Multi-Connect July 2008 2. Problem statements of Simple IP Multi-homing As description above, simple IP multi-homing can not work currently, there are several reasons cause it invalid, the specifics are listed as follows: 2.1. Default Gateway The Windows operating system in the host obeys the default gateway mechanism, which will choose the unify gateway among more than one default routes (!o0.0.0.0!+/-), it can be seen in the last row of the host route table. The default gateway guarantees there always has a route to network when the host can not find a specific route for a datagram in the route table. But when it comes to multi-homing, the default gateway also causes all the flows go out through one interface, although there has more than one network connections. Nowadays there are diverse networks can be chosen by the user, and the terminal have the capability and interfaces to connect to more than one networks at the same time. It is possible and necessary for the user to require connecting to different networks to ensure the best user experiences of different services, but the default gateway will invalidate the requirement. Although you can connect your host to several networks physically, and each network has already assigned a IP address for your host interface, even you can see different default routes in the route table, all the flow goes to the unify default gateway chosen by the operation system other than different gateways actually. 2.2. Metric Rules The default gateway is chosen based on the metric rule. The one have the lowest metric value becomes to the default gateway among several connected gateways, and the interface correspond to this gateway turns to be the default interface. Current metric rules define the 100M bps Ethernet network card to be 20 and 10M bps to be 30. But it is not a strict definition, and the user can change the metric value manually. The problem is not every network card obey the metric rules, which represents the lower metric value is, the faster route is, so that the operating system can always choose the best performance route as the default one for the user. For example, CDMA data card set its metric value as 1, although its speed is lower than 100M bps Ethernet network card. In this situation, the operating system will choose the CDMA connection as the default one, so the user is forced to use the slower connection, which violates the aim of the metric rule. Hui & Deng Expires January 8, 2009 [Page 4] Internet-Draft IP Multi-Connect July 2008 2.3. Weak and Strong Host Model There exists two different host model today, which are weak host model and strong host model, described in RFC 1122. The weak host model causes the default gateway behavior is possible, for the destination is host other than a specific interface. Reversely, the strong host model divides the host to several separated hosts logically, what means the flow can only use the specific interface. The problem is current host operating system such as Windows 2000/XP all apply weak host model on its network interface, so the host can not differ the flow to different interfaces, only the default gateway is applied. Hui & Deng Expires January 8, 2009 [Page 5] Internet-Draft IP Multi-Connect July 2008 3. Analysis of Related Work in IETF Multi-homing is a wide topic contains different aspects, and there are some work groups in IETF worked on a certain aspect of multi- homing. This section explains their work, and compares the covered field with the simple IP multi-homing. In the end we will find the simple IP multi-homing is still a problem which is not solved yet. 3.1. Multi6 Multi6 WG in IETF focuses on the multi-homed site, which has more than one connection to the public internet with those connections through either the same or different ISPs. The reasons to choose site multi-homing are to improve fault tolerance, perform load balancing, etc. The Multi6 WG mainly focuses on multi-homing solutions that tend to minimize adverse impacts on the end-to-end routing system and limit the number of prefixes that need to be advertised in the Default-Free Zone (DFZ). The background is site multi-homing today is done largely by having a site obtain a dedicated block of address space and then advertising a route for its prefix through each of its ISP connections. A site's ISPs in turn advertise the prefix to some or all of their upstream connections and the route for the prefix may propagate to all of the routers connected to the default-free zone. As the number of sites multi-homing in this manner increase, the number of routes propagated throughout the DFZ increases and overall routing stability decreases because of the burden on convergence time. Multi6 WG tries to solve this by defining a set of goals for IPv6 site multi-homing architecture, and analyzing the current limitations and the approaches to the site multi-homing. What!_s need to notice is that the working group is not chartered to make significant changes to the nature of IP addresses or to inter-domain routing. Obviously, the site multi-homing does not consider the host multiple connection which is the key problem in simple IP multi-homing. 3.2. Shim6 Shim6 is another WG in IETF aims at site multi-homing. Shim6 work is based on the architecture developed by the Multi6 WG, and completes the required protocol developments and the architecture and security analysis of the required protocols. Different with Multi6, Shim6 focuses on surviving hosts on the multi-homing site from the changes or for creating new associations, when one or more of the site!_s Hui & Deng Expires January 8, 2009 [Page 6] Internet-Draft IP Multi-Connect July 2008 address prefixes becomes unreachable. Shim6 WG produces specifications for an IPv6-based site multi-homing solution that inserts a new sub-layer (shim) into the IP stack of end-system hosts. It enables hosts on multi-homed sites to use a set of provider-assigned IP address prefixes and switch between them without upsetting transport protocols or applications. But it can not support connecting to all the ISPs simultaneously. 3.3. Monami6 The objective of the Monami6 WG is to produce a clear problem statement and to produce standard track specifications to the straight-forward problems associated with the simultaneous use of multiple addresses for either mobile hosts using Mobile IPv6 or mobile routers using NEMO Basic Support and their variants (FMIPv6, HMIPv6,etc). The WG does not define a tunnel selection mechanism, but document how to use existing mechanisms based upon preferences or policies. They explain the limitations for mobile hosts using multiple simultaneous Care-of Addresses and Home Agent addresses using Mobile IPv6, whether issues are specific to Mobile IPv6 or not. They also deliver a protocol extension to Mobile IPv6 (RFC 3775) and NEMO Basic Support (RFC 3963) to support the registration of multiple Care-of Addresses at a given Home Agent address [Standard Track]. What!_s more, Monami6 WG makes a "Flow/binding policies exchange" solution for an exchange of policies from the mobile host/router to the Home Agent and from the Home Agent to the mobile host/router influencing the choice of the Care-of Address and Home Agent address. Monami6 focus the same field with simple IP multi-homing, which is ensuring simultaneous use of multiple addresses for the host. The difference is Monami6 puts this aim to under a certain condition, the mobile host using MIP6, while the simple IP multi-homing focuses on ordinary host using IPv4/6. 3.4. Proxy Mobile IPv6 Hui & Deng Expires January 8, 2009 [Page 7] Internet-Draft IP Multi-Connect July 2008 4. Requirements for Simple IP Multi-homing Based on problem statements and related work analysis, the requirements for simple IP multi-homing is concluded and listed as follows: 1) The host with multiple network interfaces should be capable to connect with different networks simultaneously. 2) The default gateway mechanism needs to be improved to support several gateways working at the same time. 3) New metric rules must be defined to adapt to divers network cards nowadays. 4) The policies to assign different flows to the appropriate interface are required, and how to apply the policies to the host need to be considered as well. Hui & Deng Expires January 8, 2009 [Page 8] Internet-Draft IP Multi-Connect July 2008 5. IANA Considerations This document doesn't require any new number from IANA. Hui & Deng Expires January 8, 2009 [Page 9] Internet-Draft IP Multi-Connect July 2008 6. Security Considerations This document doesn't propose any new protocol. Hui & Deng Expires January 8, 2009 [Page 10] Internet-Draft IP Multi-Connect July 2008 7. References 7.1. Normative References [RFC1122] Braden, R., "Requirements for Internet Hosts - Communication Layers", STD 3, RFC 1122, October 1989. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3582] Abley, J., Black, B., and V. Gill, "Goals for IPv6 Site- Multihoming Architectures", RFC 3582, August 2003. [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in IPv6", RFC 3775, June 2004. [RFC4177] Huston, G., "Architectural Approaches to Multi-homing for IPv6", RFC 4177, September 2005. 7.2. Informative References [MONAMI6] Ernst, T., "Motivations and Scenarios for Using Multiple Interfaces and global Addresses", May 2008, . Hui & Deng Expires January 8, 2009 [Page 11] Internet-Draft IP Multi-Connect July 2008 Authors' Addresses Min Hui China Mobile 53A,Xibianmennei Ave., Xuanwu District, Beijing 100053 China Email: huimin.wti@gmail.com Hui Deng China Mobile 53A,Xibianmennei Ave., Xuanwu District, Beijing 100053 China Email: denghui02@gmail.com Hui & Deng Expires January 8, 2009 [Page 12] Internet-Draft IP Multi-Connect July 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). 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. 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