Network Working Group V. Sastry
Request for Comments: 4917 Samsung Electronics
Category: Standards Track K. Leung
A. Patel
Cisco Systems
June 2007
Mobile IPv4 Message String Extension
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The IETF Trust (2007).
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 messages. This extension carries a text string
that is intended for the user of the Mobile Node.
Table of Contents
1. Introduction ....................................................2
2. Terminology .....................................................2
3. Mobile IPv4 Message String Extension Format .....................2
4. Operation and Use of the Message String Extension ...............3
5. Security Considerations .........................................4
6. IANA Considerations .............................................4
7. Acknowledgements ................................................5
8. Normative References ............................................5
Sastry, et al. Standards Track [Page 1]
RFC 4917 Mobile IPv4 Message String Extension June 2007
1. Introduction
This document specifies a new skippable extension that can be added
by the Foreign Agent and Home Agent in any registration message
targeted for the Mobile Node. Such a message may be either a
Registration Reply or Registration Revocation (i.e., co-located
Care-of Address mode). For the Registration Reply message, this
extension can be added regardless of whether the registration has
succeeded or failed.
The content of the text string in this extension and its usage by the
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 a registration
failure reason, or give 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. For
example, a string like "registration failed : Prepaid Quota for the
user is exhausted" can give a human readable description of the
result of Mobile IP registration.
2. Terminology
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 RFC 2119 [RFC2119].
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:
145: An 8-bit identifier of the type mobility option.
Sastry, et al. Standards Track [Page 2]
RFC 4917 Mobile IPv4 Message String Extension June 2007
Length:
An 8-bit unsigned integer. Length of the extension, in bytes,
excluding the extension Type and the extension Length fields.
This field MUST be set to 1 plus the total length of the Text
field.
Sub-Type:
1: Extension comes from the Home Agent
2: Extension comes from the Foreign Agent
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