Internet DRAFT - draft-cao-mif-ongoing-session
draft-cao-mif-ongoing-session
MIF Working Group Z. Cao
Internet-Draft D. Liu
Intended status: Informational China Mobile
Expires: July 3, 2011 January 4, 2011
Holding the Ongoing Sessions on MIF Hosts
draft-cao-mif-ongoing-session-01
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.
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This Internet-Draft will expire on April 23, 2011.
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. The Problem . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Existing and Proposed Mechanism . . . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
6. Normative References . . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9
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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.
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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.
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3. Existing and Proposed Mechanism
Symbian OS an application can stick to the old interface for the time
of its choosing even after higher priority interface has become
available. This helps the app to move on time of its choosing.
Generally speaking, the connection manager can add a specific route
for the ongoing session. Even a better interface is enabled, the
application still binds to the old interface, so as to avoid changing
the interfaces from time to time.
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4. Security Considerations
TBD.
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5. IANA Considerations
This document does not require any IANA actions.
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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.
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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
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