Mobile IP Working Group Alpesh Patel
INTERNET DRAFT Kent Leung
14 October, 2003 Cisco Systems
Experimental Message, Extension and Error Codes for Mobile IPv4
draft-patel-mobileip-experimental-messages-02.txt
Status of this Memo
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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.
Mobile IPv4 defines a general Extension mechanism to allow
optional information to be carried by Mobile IP control
messages. Extensions are not skippable, if defined in range [0-
127] and skippable, if defined in range [128-255]. This
document reserves extension types in both the skippable and
non-skippable range for experimental use.
Also, Mobile IPv4 defines error codes for use by FA [64-127]
and HA [128-192]. This document reserves an error code in both
these ranges for experimental use.
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Table of Contents
1. Introduction..............................................2
2. Terminology...............................................3
3. Experimental Message......................................3
4. Experimental Extensions...................................4
4.1 Non-skippable Experimental Extension.....................4
4.2 Skippable Experimental Extension.........................5
5. Experimental Error Codes..................................6
6. Mobility Entity Considerations............................6
7. IANA Considerations.......................................6
8. Security Considerations...................................6
9. Backward Compatibility Considerations.....................6
10. Intellectual Property Rights.............................7
11. Acknowledgements.........................................7
12. References...............................................7
13. Contact Information......................................8
Full Copyright Statement.....................................8
1. Introduction
Mobile IPv4 message types range from 0 to 255. This document
reserves a message type for experimental purpose, 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 collision.
Also, 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 range [0-
127] and skippable, if defined in range [128-255]. This
document reserves extension types in both the skippable and
non-skippable range for experimental use.
Mobile IPv4 defines error codes for use by FA [64-127] and HA
[128-192]. This document reserves an error code in both these
ranges for experimental use.
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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].
EXP-MSG-TYPE: A message in the range [0-255] to be assigned by
IANA for experimental use.
EXP-SKIP-EXT-TYPE: Extension in the range [128-255] to be
assigned by IANA for experimental use.
EXP-NONSKIP-EXT-TYPE: Extension in the range [0-127] to be
assigned by IANA for experimental use.
EXP-HA-ERROR-CODE: Error code in the range [128-192] for use by
HA in reply messages to indicate error condition.
EXP-FA-ERROR-CODE: Error code in the range [64-127] for use by
FA in reply messages to indicate error condition.
3. Experimental Message
Since the nature and purpose of an experimental message cannot
be known in advance, the structure is defined as 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.
These messages will be used between the mobility entities (Home
Agent, Foreign Agent, and Mobile Node). Experimental messages
SHOULD 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 variable
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Destination Port 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 The Opaque is zero or more octets.
Once an experimental message has been tested and shown to be
useful, a permanent number could be obtained through the normal
assignment procedures.
A single experimental message type is recommended since this
message can contain extensions based on which the message can
be interpreted.
4. Experimental Extensions
This document reserves extensions in both skippable and non-
skippable range for experimental purposes. The long extension
format (for non-skippable extensions) and short extension
format (for skippable extensions), as defined [2] are used for
experimental extensions.
4.1 Non-skippable Experimental Extension
This format is applicable for non-skippable extensions, which
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 à
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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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 bytes.
Opaque The Opaque is zero or more octets.
Since the length field is 16 bits wide, the extension data can
exceed 256 bytes in length.
4.2 Skippable 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 bytes.
Sub-Type is a unique number given to each member in the
aggregated type.
Opaque The Opaque is zero or more octets.
Since the length field is 8 bits wide, the extension data
cannot exceed 256 bytes in length.
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5. Experimental Error Codes
This document reserves reply error code EXP-FA-ERROR-CODE, in
the range [64-127], for use by FA. This document also reserves
reply error code EXP-HA-ERROR-CODE, in the range [128-192], for
use by HA.
These experimental error codes may be included in registration
reply messages.
It is recommended that experimental error code must be included
in experimental messages or messages containing at-least one
experimental extension.
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 later case, it is
suggested that experimental extensions MUST not be used in
deployed products and usage be restricted to experimentations
only.
7. IANA Considerations
IANA services are required for this draft. Since a new message
type is needed to be reserved as experimental, a value must be
assigned for EXP-MSG-TYPE from Mobile IP control message space.
Also, values for EXP-NONSKIP-EXT-TYPE and EXP-SKIP-EXT-TYPE
must be assigned for experimental extensions.
Also, values for EXP-HA-ERROR-CODE and EXP-FA-ERROR-CODE must
be assigned for experimental error code.
8. Security Considerations
Like all Mobile IP control messages, the experimental messages
SHOULD be authenticated with at least one authenticator.
Messages without a valid authenticator SHOULD be discarded.
9. Backward Compatibility Considerations
Mobility entities that donÆt understand the experimental
message MUST silently discard it.
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Mobility entities that donÆt understand the experimental
skippable extensions MUST ignore them. Mobility entities that
donÆt understand the non-skippable experimental extensions MUST
silently discard the message containing them.
FA and HA SHOULD include experimental error code in 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. Intellectual Property Rights
The IETF takes no position regarding the validity or scope of
any intellectual property 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; neither does
it represent that it has made any effort to identify any such
rights. Information on the IETF's procedures with respect to
rights in standards-track and standards-related documentation
can be found in BCP-11. Copies of claims of rights made
available for publication and any assurances of licenses to be
made available, or the result of an attempt made to obtain a
general license or permission for the use of such proprietary
rights by implementors or users of this specification can be
obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention
any copyrights, patents or patent applications, or other
proprietary rights which may cover technology that may be
required to practice this standard. Please address the
information to the IETF Executive Director.
11. 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 draft-narten-
iana-experimental-allocations-03.txt for general guidelines.
12. References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
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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.
[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
13. Contact Information
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 Kent Leung
Cisco Systems Cisco Systems
170 W. Tasman Drive, 170 W. Tasman Drive,
San Jose, CA 95134 San Jose, CA 95134
USA USA
Email: alpesh@cisco.com Email: kleung@cisco.com
Phone: +1 408-853-9580 Phone: +1 408-526-5030
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