Mobile IP Working Group Alpesh Patel INTERNET DRAFT Kent Leung 10 September 2004 Cisco Systems Experimental Message, Extension and Error Codes for Mobile IPv4 draft-ietf-mip4-experimental-messages-02.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 March 9, 2005. Copyright Notice Copyright (c) The Internet Society (2004). All Rights Reserved. Abstract Mobile IPv4 message types range from 0 to 255. This document reserves a message type for use by an individual, company, or organization for experimental purpose, to evaluate enhancements to Mobile IPv4 messages before formal standards proposal. Patel, Leung Expires March 9, 2005 [Page 1] Internet Draft Experimental Mesg., Ext. & Error Codes September 2004 Table of Contents 1. Introduction.............................................2 2. Terminology..............................................3 3. Experimental Message.....................................3 4. Experimental Extensions..................................4 4.1 Non-skippable Mobile IPv4 Experimental Extension........5 4.2 Non-skippable ICMP Router Discovery Exp. Extension......5 4.3 Skippable Mobile IPv4 Experimental Extension............6 4.4 Skippable ICMP Router Discovery Experimental Extension..7 5. Experimental Error Codes.................................7 6. Mobility Entity Considerations...........................7 7. IANA Considerations......................................8 7.1 New Message Type........................................8 7.2 New Extension Values....................................8 7.3 New Error Codes.........................................8 9. Backward Compatibility Considerations....................9 10. Acknowledgements........................................9 11. References..............................................9 11.1 Normative References..................................10 11.2 Informative References................................10 12. Authors' Addresses.....................................10 Intellectual Property Statement............................11 Disclaimer of Validity.....................................11 Copyright Statement........................................11 1. Introduction Mobile IPv4 message types range from 0 to 255. This document reserves a message type for experimental purposes, to evaluate enhancements to Mobile IPv4 messages before formal standards proposal. Without experimental message capability, one would have to select a type value from the range defined for IANA assignment, which may result in collisions. Within a message, Mobile IP defines a general extension mechanism to allow optional information to be carried by Mobile IP control messages. Extensions are not skippable if defined in the range [0-127] and skippable if defined in the range [128- 255]. This document reserves extension types in both the skippable and non-skippable ranges for experimental use. Patel, Leung Expires March 9, 2005 [Page 2] Internet Draft Experimental Mesg., Ext. & Error Codes September 2004 Mobile IPv4 defines error codes for use by the FA [64-127] and HA [128-192]. This document reserves an error code in both these ranges for experimental use. The definition of experimental numbers in this document is done according to the recommendation of Section 2.2 of BCP 82, RFC 3692. 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 [1]. In addition, this document frequently uses the following terms: EXP-MSG-TYPE: A Mobile-IPv4 message number in the range [0-255] to be assigned by IANA for experimental use. EXP-SKIP-EXT-TYPE: A Mobile-IPv4 and ICMP router discovery Agent Advertisement extension number in the range [128-255] to be assigned by IANA for experimental use. EXP-NONSKIP-EXT-TYPE: A Mobile-IPv4 and ICMP router discovery Agent Advertisement extension number in the range [0-127] to be assigned by IANA for experimental use. EXP-HA-ERROR-CODE: A Mobile-IPv4 error code in the range [128- 192] for use by HA in MIPv4 reply messages to indicate an error condition. EXP-FA-ERROR-CODE: A Mobile-IPv4 error code in the range [64- 127] for use by FA in reply messages to indicate error condition. Mobility Entity: Entities as defined in [2] (home agent, foreign agent and mobile node). 3. Experimental Message Since the nature and purpose of an experimental message cannot be known in advance, the structure is defined as having an opaque payload. Entities implementing the message can interpret the message as per their implementation. One suggestion is to interpret based on extensions present in the message. Patel, Leung Expires March 9, 2005 [Page 3] Internet Draft Experimental Mesg., Ext. & Error Codes September 2004 These messages may be used between the mobility entities (Home Agent, Foreign Agent, and Mobile Node). Experimental messages MUST be authenticated using any of the authentication mechanism defined for Mobile IP ([2], [5]). This message MAY contain extensions defined in Mobile IP, including vendor specific extensions [4]. IP fields: Source Address: Typically the interface address from which the message is sent. Destination Address: The address of the agent or the Mobile Node. UDP fields: Source Port Set according to RFC 768 (variable) Destination Port Set to the value 434 Mobile IP fields shown below follow the UDP header: 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 | Opaque. . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type EXP-MSG-TYPE (To be assigned by IANA) Opaque Zero or more octets of data, with structure defined only by the particular experiment it is used for. Once an experimental message has been tested and shown to be useful, a permanent number should be obtained through the normal IANA numbers assignment procedures. A single experimental message type is defined. This message can contain extensions based on which the message can be interpreted. 4. Experimental Extensions This document reserves Mobile IPv4 extensions in both the skippable and non-skippable ranges for experimental purposes. The long extension format (for non-skippable extensions) and Patel, Leung Expires March 9, 2005 [Page 4] Internet Draft Experimental Mesg., Ext. & Error Codes September 2004 short extension format (for skippable extensions), as defined by [2], are used for Mobile IPv4 experimental extensions. Also, ICMP router discovery extension numbers in both the skippable and non-skippable ranges are reserved for experimental use. 4.1 Non-skippable Mobile IPv4 Experimental Extension This format is applicable for non-skippable extensions and may carry information more than 256 bytes. 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 | Sub-Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Opaque. . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type EXP-NONSKIP-EXT-TYPE (to be assigned by IANA) is the type, which describes an experimental extension. Sub-Type is a unique number given to each member in the aggregated type. Length Indicates the length (in bytes) of the data field within this extension. It does NOT include the Type, Sub-Type and Length fields. Opaque Zero or more octets of data, with structure defined only by the particular experiment it is used for. Since the length field is 16 bits wide, the extension data can exceed 256 bytes in length. 4.2 Non-skippable ICMP Router Discovery Exp. Extension This format is applicable for non-skippable extensions. 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 | Opaque . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Patel, Leung Expires March 9, 2005 [Page 5] Internet Draft Experimental Mesg., Ext. & Error Codes September 2004 Type EXP-NONSKIP-EXT-TYPE (to be assigned by IANA) is the type, which describes an ICMP router discovery experimental extension. Length Indicates the length (in bytes) of the data field within this extension. It does NOT include the Type and Length fields. Opaque Zero or more octets of data, with structure defined only by the particular experiment it is used for. A node which receives a router advertisement with this extension should ignore the extension if it does not recognize it. A mobility entity which understands this extension, but does not recognize it, should drop (ignore) the router advertisement. 4.3 Skippable Mobile IPv4 Experimental Extension This format is applicable for skippable extensions, which carry information less than 256 bytes. 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 | Opaque. . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type EXP-SKIP-EXT-TYPE (to be assigned by IANA) is the type, which describes an experimental extension. Length Indicates the length (in bytes) of the data field within this extension. It does NOT include the Type and Length fields. Sub-Type is a unique number given to each member in the aggregated type. Opaque Zero or more octets of data, with structure defined only by the particular experiment it is used for. Since the length field is 8 bits wide, the extension data cannot exceed 256 bytes in length. Patel, Leung Expires March 9, 2005 [Page 6] Internet Draft Experimental Mesg., Ext. & Error Codes September 2004 4.4 Skippable ICMP Router Discovery Experimental Extension This format is applicable for skippable ICMP router discovery extensions. This extension should be ignored if an implementation does not understand it. 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 | Opaque. . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type EXP-SKIP-EXT-TYPE (to be assigned by IANA) is the type, which describes an experimental extension. Length Indicates the length (in bytes) of the data field within this extension. It does NOT include the Type and Length fields. Opaque Zero or more octets of data, with structure defined only by the particular experiment it is used for. 5. Experimental Error Codes This document reserves reply error code EXP-FA-ERROR-CODE for use by the FA. This document also reserves reply error code EXP-HA-ERROR-CODE for use by the HA. These experimental error codes may be used in registration reply messages. It is recommended that experimental error codes be used with experimental messages and extensions whenever none of the standardized error codes are applicable. 6. Mobility Entity Considerations Mobility entities can send and receive experimental messages. Implementations that don't understand the message type SHOULD silently discard the message. Experimental extensions can be carried in experimental messages and standards defined messages. In the latter case, it is Patel, Leung Expires March 9, 2005 [Page 7] Internet Draft Experimental Mesg., Ext. & Error Codes September 2004 suggested that experimental extensions MUST NOT be used in deployed products and usage be restricted to experimentations only. 7. IANA Considerations This document defines a control message to be used between mobility entities, two new extension formats and two new error codes. To ensure correct interoperation based on this specification, IANA has reserved values in the Mobile IPv4 number space, as defined in [2] for one new message type, two new extensions and two error codes. 7.1 New Message Type A new Mobile IPv4 control message using UDP port 434, type EXP- MSG-TYPE has been defined by IANA. This value has been taken from the same number space as Mobile IP Registration Request (Type = 1), and Mobile IP Registration Reply (Type = 3). (The value 255 is suggested in this case). 7.2 New Extension Values The following extension types are introduced by this specification: Experimental non-skippable extension: The value for EXP- NONSKIP-EXT-TYPE has been assigned from the numbering space for non-skippable extensions, which may appear in Mobile IPv4 control messages. Also, the same number, EXP-NONSKIP-EXT-TYPE has been assigned from the numbering space for non-skippable extensions, which may appear in ICMP router discovery messages. (The value 127 is suggested in both cases.) Experimental skippable extension: The value EXP-SKIP-EXT-TYPE has been assigned from the numbering space for skippable extensions, which may appear in Mobile IPv4 control messages. Also, the same number, EXP-SKIP-EXT-TYPE has been assigned from the numbering space for skippable extensions which may appear in ICMP router discovery messages. (The value 255 is suggested in both cases.) 7.3 New Error Codes Patel, Leung Expires March 9, 2005 [Page 8] Internet Draft Experimental Mesg., Ext. & Error Codes September 2004 The value EXP-HA-ERROR-CODE has been defined by IANA to be used as code field in messages generated by HA. (The value 192 is suggested for this code.) Also, value EXP-FA-ERROR-CODE has been defined by IANA to be used as the code field in messages generated by the FA. (The value 127 is suggested for this code.) 8. Security Considerations Like all Mobile IP control messages, the experimental messages MUST be authenticated as per the requirements specified in [2] or [5]. Experimental messages without a valid authenticator SHOULD be discarded. 9. Backward Compatibility Considerations Mobility entities that don't understand the experimental message MUST silently discard it. Mobility entities that don't understand the experimental skippable extensions MUST ignore them. Mobility entities that don't understand the non-skippable experimental extensions MUST silently discard the message containing them. This behavior is consistent with section 1.8 of [2]. Foreign Agents and Home Agents SHOULD include an experimental error code in a reply message only if they have a general indication that the receiving entity would be able to parse it. An indication of this is if the request message was of type EXP-MSG-TYPE or contained at least one experimental extension. 10. Acknowledgements The authors would like to acknowledge Henrik Levkowetz for his detailed review of the draft and suggestion to incorporate experimental extensions in this draft. The authors would also like to acknowledge Thomas Narten for his initial review of the draft and reference to [6] for general guidelines. 11. References Patel, Leung Expires March 9, 2005 [Page 9] Internet Draft Experimental Mesg., Ext. & Error Codes September 2004 11.1 Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Perkins, C., "IP Mobility Support", RFC 3344, August 2002. [3] Reynolds, J. and J. Postel, "Assigned Numbers", STD 2, RFC 1700, October 1994. 11.2 Informative References [4] G. Dommety, K. Leung, "Mobile IP Vendor/Organization-Specific Extensions" RFC 3115, April 2001 [5] C. Perkins, P. Calhoun, "Mobile IPv4 Challenge/Response Extensions", RFC 3012, November 2000 [6] T. Narten, "Assigning Experimental and Testing Numbers Considered Useful", BCP 82, RFC 3692, January, 2004 12. Authors' Addresses Questions and comments about this draft should be directed at the Mobile IPv4 working group: mip4@ietf.org Questions and comments about this draft may also be directed to the authors: Alpesh Patel Cisco Systems 170 W. Tasman Drive, San Jose, CA 95134 USA Email: alpesh@cisco.com Phone: +1 408-853-9580 Kent Leung Cisco Systems 170 W. Tasman Drive, San Jose, CA 95134 USA Email: kleung@cisco.com Patel, Leung Expires March 9, 2005 [Page 10] Internet Draft Experimental Mesg., Ext. & Error Codes September 2004 Phone: +1 408-526-5030 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 (2004). 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. Patel, Leung Expires March 9, 2005 [Page 11] Internet Draft Experimental Mesg., Ext. & Error Codes September 2004 Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Patel, Leung Expires March 9, 2005 [Page 12]