MIF Working Group Z. Cao Internet-Draft D. Liu Intended status: Informational China Mobile Expires: January 5, 2011 July 4, 2010 Holding the Ongoing Sessions on MIF Hosts draft-cao-mif-ongoing-session-00 Abstract This document discusses the problem of holding the ongoing sessions on a multi-homed host. When there is an application running on one interface and another interface with a better routing metric is enabled, it is desirable to hold the application on the current interface and avoid it being terminated and shifted to another interface. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as Cao & Liu Expires January 5, 2011 [Page 1] Internet-Draft MIF Ongoing Session July 2010 described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. The Problem . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Proposed Mechanism . . . . . . . . . . . . . . . . . . . . . . 5 4. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 6. Normative References . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 Cao & Liu Expires January 5, 2011 [Page 2] Internet-Draft MIF Ongoing Session July 2010 1. Introduction Current laptops, personal computers and smart phones typically have multiple access network interfaces and are able to connect to them simultaneously. MIF Working Group is chartered to study the problems raised by multiple interface hosts connecting to different domains. The central problem [MIF-PS] faced by MIF is that the configuration objects are usually provided via a node-scoped way while the desired behavior is domain-scoped. This document discusses the problem of holding the ongoing sessions on a multi-homed host. When there is an application running on one interface and another interface with a better routing metric is enabled, it is desirable to hold the application on the current interface and avoid it being terminated and shifted to another interface. Cao & Liu Expires January 5, 2011 [Page 3] Internet-Draft MIF Ongoing Session July 2010 2. The Problem The problem is illustrated in Figure 1. Suppose the host has two interfaces, If-1 and If-2, and If-2 has a better metric than If-1. So if both If-1 and If-2 are enabled, the default route on the host will be going through If-2. For example, If-1 is a WiFi interface, and If-2 is a wired ethernet interface. Suppose the host initially only enables If-1 with IP address 10.1.1.0/24, and the host has an on-going session with the remote server. This on-going session is routed via Interface-1 and through Net-1. At this time, when this session is still going on, the host enables If-2. Because If-2 has a better metric than If-1, and if there is not a specific route on the host towards the remote server, the default route on the host will take effect and all outbound traffic will be routed via If-2. Consequently, the on-going session will be terminated. In order to continue communicating with the remote server, the host should normally try to re-connect the server via If-2. If the client application is able to retain the data got from the on- going session, the reconnection will take effect. Otherwise, the data got from the previous session will completely be discarded. It is desirable to hold the on-going session on the interface that serves it. +--------+ +------------------| Net-1 |------------------+ If-1|10.1.1.0/24 +--------+ | +-------+ +-------+ | Host | | Server| +-------+ +-------+ If-2|10.1.2.0/24 +--------+ | +------------------| Net-2 |------------------+ +--------+ Figure 1: Problem of Holding the Ongoing Session We have tested this scenario on Windows XP PCs. The host first only enables its WLAN interface and launches a FTP download. While the download session is going on one interface, we turn on the wired interface. The FTP session will be terminated on the WLAN interface and switched to the wired interface. Cao & Liu Expires January 5, 2011 [Page 4] Internet-Draft MIF Ongoing Session July 2010 3. Proposed Mechanism TBD. Cao & Liu Expires January 5, 2011 [Page 5] Internet-Draft MIF Ongoing Session July 2010 4. Security Considerations TBD. Cao & Liu Expires January 5, 2011 [Page 6] Internet-Draft MIF Ongoing Session July 2010 5. IANA Considerations This document does not require any IANA actions. Cao & Liu Expires January 5, 2011 [Page 7] Internet-Draft MIF Ongoing Session July 2010 6. Normative References [MIF-PS] Blanchet, M. and P. eite, "Multiple Interfaces Problem Statement", draft-ietf-mif-problem-statement-02.txt (work in progress), March 2010. Cao & Liu Expires January 5, 2011 [Page 8] Internet-Draft MIF Ongoing Session July 2010 Authors' Addresses Zhen Cao China Mobile Unit2, 28 Xuanwumenxi Ave,Xuanwu District Beijing 100053 China Email: zehn.cao@gmail.com Dapeng Liu China Mobile Unit2, 28 Xuanwumenxi Ave,Xuanwu District Beijing 100053 China Email: liudapeng@chinamobile.com Cao & Liu Expires January 5, 2011 [Page 9]