Network Working Group V. Sastry Internet-Draft K. Leung Expires: September 16, 2005 A. Patel Cisco Systems March 18, 2005 Mobile IPv4 Message String Extension draft-sastry-mip4-string-extension-01.txt Status of this Memo By submitting this Internet-Draft, I certify that any applicable patent or other IPR claims of which I am aware have been disclosed, and any of which I become aware will be disclosed, in accordance with RFC 3668. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on September 16, 2005. Copyright Notice Copyright (C) The Internet Society (2005). All Rights Reserved. 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. Sastry, et al. Expires September 16, 2005 [Page 1] Internet-Draft Mobile IPv4 Message String Extension March 2005 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Mobile IPv4 Message String Extension . . . . . . . . . . . . 5 4. Operation and use of the Message String Extension . . . . . 6 5. Security Considerations . . . . . . . . . . . . . . . . . . 7 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . 8 7. Normative References . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 8 Intellectual Property and Copyright Statements . . . . . . . 10 Sastry, et al. Expires September 16, 2005 [Page 2] Internet-Draft Mobile IPv4 Message String Extension March 2005 1. Introduction This document specifies a new skippable extension that can be added by Foreign Agent and Home Agent in Registration Reply message. This extension can be added to Registration Reply message, independent of whether the registration has succeeded or failed. Content of the text string in this extension and it's 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. Sastry, et al. Expires September 16, 2005 [Page 3] Internet-Draft Mobile IPv4 Message String Extension March 2005 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. Sastry, et al. Expires September 16, 2005 [Page 4] Internet-Draft Mobile IPv4 Message String Extension March 2005 3. Mobile IPv4 Message String Extension The Message String Extension confirms 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 field Sub-Type: 1: if the extension is added by Home Agent 2: if the extension is added by Foreign Agent Text: 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. Sastry, et al. Expires September 16, 2005 [Page 5] Internet-Draft Mobile IPv4 Message String Extension March 2005 4. Operation and use of the Message String Extension The Message String Extension is only valid for use within Mobile IPv4 Registration Reply messages. The Message String Extension is a skippable extension. Either Home Agent or Foreign Agent or both can add Message String Extension to Registration Reply 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 Reply message to a Mobile Node. However, as Mobile Node can retransmit the Registration Request, 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 timestamp mismatch and may attach a Message String Extension for the same. The client can adjust it's timestamp and send second Registration Request. Home Agent may accept the Registration Request and add a different Message String Extension to the corresponding Registration Reply message. Sastry, et al. Expires September 16, 2005 [Page 6] Internet-Draft Mobile IPv4 Message String Extension March 2005 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) , 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), it MUST appear after the Mobile-Home Authentication Extension [RFC3344] and it MAY appear before the Mobile-Foreign Authentication Extension. If Mobile Node cannot understand this extension, it should be skipped. Sastry, et al. Expires September 16, 2005 [Page 7] Internet-Draft Mobile IPv4 Message String Extension March 2005 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-mip4-faerr-00.txt (work in progress), October 2004. [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. Authors' Addresses Venkateshwara Sastry Cisco Systems 170 W. Tasman Drive San Jose, CA 95134 US Phone: +91 80-25318090 EMail: vsastry@cisco.com Sastry, et al. Expires September 16, 2005 [Page 8] Internet-Draft Mobile IPv4 Message String Extension March 2005 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 Sastry, et al. Expires September 16, 2005 [Page 9] Internet-Draft Mobile IPv4 Message String Extension March 2005 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. 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Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement Copyright (C) The Internet Society (2005). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Sastry, et al. Expires September 16, 2005 [Page 10]