Internet DRAFT - draft-sastry-mip4-string-extension
draft-sastry-mip4-string-extension
Network Working Group V. Sastry
Internet-Draft K. Leung
Expires: April 7, 2006 A. Patel
Cisco Systems
October 04, 2005
Mobile IPv4 Message String Extension
draft-sastry-mip4-string-extension-03.txt
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Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
This document specifies a new extension for use in Mobile IPv4. This
extension can be added by the Home Agent and the Foreign Agent to
Registration Reply message. This extension carries a text string
that is intended for the user of the Mobile Node.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Mobile IPv4 Message String Extension Format . . . . . . . . . 5
4. Operation and Use of the Message String Extension . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. Normative References . . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
Intellectual Property and Copyright Statements . . . . . . . . . . 11
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1. Introduction
This document specifies a new skippable extension that can be added
by Foreign Agent and Home Agent in registration message targeted for
the Mobile Node. Such a message may be either a Registration Reply
or Registration Revocation (i.e. collocated Care-of Address mode).
For the Registration Reply message, this extension can be added
regardless of whether the registration has succeeded or failed.
Content of the text string in this extension and its usage by Mobile
Node is implementation specific. The text string in this extension
is intended for the user of the Mobile Node. For example, this
message can be displayed on the Mobile Node's user interface, logged
or handled in any other implementation dependent way, depending on
the form of the Mobile Node.
Typical contents of the text string will indicate registration
failure reason, or a welcome message on successful registration.
This is important as the failure reason code gives very limited
information for interpretation by the user of the Mobile Node. A
string like "registration failed : Prepaid Quota for the user is
exhausted", "registration success : Unauthorized Access is
Prohibited", can give a human readable description of the result of
Mobile IP registration.
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2. Terminology
The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119.
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3. Mobile IPv4 Message String Extension Format
The Message String Extension conforms to the Short Extension format
specified for Mobile IPv4 [RFC3344]. The Message String Extension is
a skippable extension.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Sub-Type | Text ....
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type:
To be assigned by IANA. An 8-bit identifier of the type mobility
option.
Length:
8-bit unsigned integer, equaling 1 plus the length in octets of
the Text
Sub-Type:
1:
Extension is added by Home Agent
2:
Extension is added by Foreign Agent
Text:
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The Text field is one or more octets, and its contents are
implementation dependent. It is intended to be human readable,
and MUST NOT affect operation of the protocol. It is recommended
that the message contain UTF-8 encoded 10646 [RFC2279] characters.
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4. Operation and Use of the Message String Extension
The Message String Extension is only valid for use within Mobile IPv4
Registration Reply and Registration Revocation messages. The Message
String Extension is a skippable extension. Either Home Agent or
Foreign Agent or both can add Message String Extension to
registration messages. Usage of Text field of the Message String
Extension is implementation dependent. For example, this message can
be displayed on the Mobile Node's user interface, logged or handled
in an implementation dependent way, depending on the form of the
Mobile Node.
Home Agent or Foreign Agent or both, MAY add the extension to each
registration message to a Mobile Node. However, Mobile Node may
throttle how often the user is notified of the message (either via
display on user interface, logging, etc.) For example, Home Agent
may reject the first Registration Request due to prepaid quota for
the user is reached and may attach a Message String Extension with
the text "Prepaid quota reached. Please contact www.paymore.com to
update balance". Mobile Node could display this on the user
interface. As a response user of the Mobile Node may take the
required action to update the prepaid account and retry the
registration process. Home Agent may accept this Registration
Request and attach a Message String Extension with the text "Welcome
to www.serviceprovider.com". Mobile Node could display this on the
user interface thus confirming successful creation of binding on Home
Agent.
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5. Security Considerations
Message String Extension can be added by Home Agent or Foreign Agent
or both.
If the extension is added by the Home Agent (extension with subtype
1) to Registration Reply or Registration Revocation message, it MUST
appear before Mobile-Home Authentication Extension [RFC3344]. If the
the Mobile Node cannot understand this extension, it should be
skipped.
If the extension is added by the Foreign Agent (extension with
subtype 2) to Registration Reply message, it MUST appear after
Mobile-Home Authentication Extension [RFC3344] whenever present.
Also the extension MUST appear before the Mobile-Foreign
Authentication Extension whenever present. If Mobile Node cannot
understand this extension, it should be skipped.
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6. IANA Considerations
This specification reserves one number for the Message String
Extension Section 3 from the space of numbers for skippable mobility
extensions (i.e., 128-255) defined for Mobile IPv4 [RFC3344] at
http://www.iana.org/assignments/mobileip-numbers.
The value 145 is recommended for this extension.
This specification also creates a new subtype space for the type
number of this extension. The subtype values 1 and 2 are defined in
this specification. The subtype value 1 is reserved for use by Home
Agent and subtype value 2 is reserved for use by Foreign Agent.
Other values can be allocated from this number space by IANA actions.
7. Normative References
[FA-ERR] Perkins, C., "Foreign Agent Error Extension for Mobile
IPv4", draft-ietf-mip4-faerr-02.txt (work in progress),
September 2005.
[RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO
10646", RFC 2279, January 1998.
[RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson,
"Remote Authentication Dial In User Service (RADIUS)",
RFC 2865, June 2000.
[RFC3344] Perkins, C., "IP Mobility Support for IPv4", RFC 3344,
August 2002.
[RFC3543] Glass, S. and M. Chandra, "Registration Revocation in
Mobile IPv4", RFC 3543, August 2003.
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Authors' Addresses
Venkateshwara Sastry
Cisco Systems
Akkithimanahalli, O'Shaugnessy Road
Bangalore 560085
India
Phone: +91 80-51033757
Email: vsastry@cisco.com
Kent Leung
Cisco Systems
170 W. Tasman Drive
San Jose, CA 95134
US
Phone: +1 408-526-5030
Email: kleung@cisco.com
Alpesh Patel
Cisco Systems
170 W. Tasman Drive
San Jose, CA 95134
US
Phone: +1 408-853-9580
Email: alpesh@cisco.com
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Acknowledgment
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Internet Society.
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