Network Working Group S. Daniel Park
Internet-Draft M. Lee
Expires: October 12, 2005 SAMSUNG Electronics
April 13, 2005
Link Characteristic Information for Mobile IP
draft-daniel-mip-link-characteristic-00.txt
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Abstract
This document introduces a new model for link characteristic
information that is sent by the mobile node to let the correspondent
node know which link is being used for communication between them.
This utility allows the correspondent node to forward its ongoing
traffics within the bandwidth of the mobile node while the mobile
node changes its link. This model can be applicable for Mobile IPv4
as well as Mobile IPv6.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Link Characteristic Information Option for Mobile IPv6 . . . . 4
4. Operational Considerations . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1 Normative References . . . . . . . . . . . . . . . . . . . . 6
8.2 Informative References . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 7
Intellectual Property and Copyright Statements . . . . . . . . 8
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1. Introduction
Mobile IP [RFC3344], [RFC3775] allows an IP node to be mobile when
changing its location and still maintain existing connections. When
the mobile node changes its location, it might also change its link.
After attaching to a new link, the mobile node sustains its
connection with the previous node (called correspondent node)
continuously via specific operation as binding update which sent by
the mobile node that is away from home to update another node with
its new address (care-of address).
Mobile Nodes are more and more equipped with several interfaces of
different L2 technologies. As such they may be reachable through
multiple links at the same time or alternatively use each interface
depending on the network environment. Mobile IP scheme, however,
does not provide which link is attached to the mobile node, but
maintain its existing connection. It means the correspondent node
recognize that the mobile node is still attached to the same link.
It can cause some trouble to communicate between them. For example,
in some case (i.e.,vertical handover), if the mobile node is attached
to the CDMA (low bandwidth link) from the 802.11b Wireless LAN (high
bandwidth link), the mobile node needs to receive a traffic within
its limited bandwidth not overwhelmed traffic from the correspondent
node, however the correspondent node will send its traffic to the
mobile node as if the 802.11b bandwidth is still guranteed. Ratio of
packet loss will eventually be increased.
This document introduces a new model for link characteristic
information that is sent by the mobile node to let the correspondent
node know which link is being used for communication between them. A
new option called Link Characteristic Information Option is defined
in this document to provide link characteristic information (i.e.,
current link bandwidth, link type, and others information will be
expanded later if required) to the mobile node while doing a binding
update. This option is recommendable to be included in the Binding
Update Message as well as Binding Acknowledgement Message when
attaching to a new link which is different from the previous link.
In wireless environment, all link is not able to support the same
bandwidth to the mobile node while attaching to the new link. If the
mobile node which is currently attached to the 802.11b link is being
moved to the new 802.11b link, the available link bandwidth is may
different between them. So link characteristic information can be
adoptable for the same link change including new extended messages.
To illustrate this model easily, Mobile IPv6 [RFC3775]is only
described in this document, Mobile IPv4 [RFC3344] will be able to be
defined following the Type-Length-Value format for Mobile IP
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Extension.
2. Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. Link Characteristic Information Option for Mobile IPv6
The Mobile Node Link Characteristic Information Option is a new
optional data field that is carried in the Mobile IPv6 defined
messages which includes the mobility header (Binding Update and
Binding Acknowledgement). Various type and bandwidth of link can be
delivered to the correspondent node from the mobile node. The
subtype field in the option defined the specific link type and
current bandwidth of the mobile node.
This option is recommendable to be carried in the Binding Update and
Binding Acknowledgement message while changing its subnet. The
subtype field in the option is used to interpret the specific link
type and link current bandwidth of the mobile node.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Option Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Subtype | Link Characteristic Information...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Option Type: To be defined by IANA
o Option Length: 8-bit unsigned integer, representing the length in
octets of the Subtype and Link Characteristic Information fields.
o Subtype: Subtype field defines the link type of the mobile node
included in the Link Characteristic Information field.
Subtype Link Type
----------------------------------------------
1 WLAN (802.11b)
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2 WLAN (802.11a)
3 WLAN (802.11g)
4 WLAN (802.11n)
5-9 Reserved for WLAN Extension
10 CDMA
11-20 Reserved for Cellular Networks
21-30 802.15 Family Networks
31-40 802.16 Family Networks
41- Reserved
----------------------------------------------
o Link Characteristic Information: A variable length of link
available bandwidth as specified link type by the subtype field of
this option.
This option does not have any alignment requirements.
4. Operational Considerations
The binding cache is a table maintained by each correspondent node
and home agent that contains the current bindings for mobile nodes.
To store link characteristic information on the correspondent node,
one entry SHOULD be contained in the binding cache. Also the
correspondent node MUST recognize this option. Otherwise, this
option is silently discarded by the correspondent node.
Link characteristic information MUST be provided by the mobile node
while attaching a new link via Binding Update message. When the
correspondent node sends Binding Acknowledgement message, Link
Characteristic Information Option which is copied from the Binding
Update message MUST be included.
Once taking an available bandwidth of the mobile node, the
correspondent node SHOULD guarantee the bandwidth when forwarding the
traffics to the mobile node. For example, The ongoing traffic
requires 10Mbps bandwidth, but the available bandwidth of the mobile
node is at most 1Mbps, then the correspondent node SHOULD reduce its
forwarding traffic amount.
In vertical handover, the mobile node can be moved to various links
such as wireless pan area, wireless lan are and cellular area and
each link has its own specific cnaracteristic information. This
option can be more valuable model for vertical handover environment
than horizontal handover.
This document only define the bandwidth information as link
characteristic, but there is no restriction to add other available
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information which will be newly defined as new subtype and link
characteristic information when anyone requires a specific
information.
5. Security Considerations
Attacker can use this option to reduce the current bandwidth
regardless of link type of the mobile node. Several mechanisms can
be adoptable for this vulnerability.
Encrypting traffic at link layer such that other users on the same
link do not see the link characteristic information. This mechanism
does not help against attackers on the rest of the path between the
mobile node and the correspondent node.
Encrypting the whole packet, such as when using IPsec to protect the
communications with the correspondent node [RFC3776].
6. IANA Considerations
IANA should record a value for Link Characteristic Option including
subtype (Mobile IPv4 Extension and Mobile IPv6 Option.
7. Acknowledgements
Understanding Mobile IPv6 whitepaper written by Microsoft on April
2004 is referred to illustrate what Mobile IPv6 is in this document.
Thanks their good summary. Specially thanks Rajeev Koodli, Bongkyo
Moon, Pyungsoo Kim and Junghoon Jee for their useful comments.
8. References
8.1 Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
8.2 Informative References
[RFC3344] Perkins, C., "IP Mobility Support for IPv4", RFC 3344,
August 2002.
[RFC3775] Johnson, D., Perkins, C. and J. Arkko, "Mobility Support
in IPv6", RFC 3775, June 2004.
[RFC3776] Arkko, J., Devarapalli, V. and F. Dupont, "Using IPsec to
Protect Mobile IPv6 Signaling Between Mobile Nodes and
Home Agents", RFC 3776, June 2004.
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Authors' Addresses
Soohong Daniel Park
Mobile Platform Laboratory, SAMSUNG Electronics.
416 Maetan-3dong, Yeongtong-gu
Suwon, Gyeonggi-do 443-742
KOREA
Phone: +82 31 200 4508
EMail: soohong.park@samsung.com
Minho Lee
Mobile Platform Laboratory, SAMSUNG Electronics.
416 Maetan-3dong, Yeongtong-gu
Suwon, Gyeonggi-do 443-742
KOREA
Phone: +82 31 200 3697
EMail: minho03.lee@samsung.com
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