Mobile IP Working Group Alpesh Patel
INTERNET DRAFT Kent Leung
11 May 2004 Cisco Systems
Experimental Message, Extension and Error Codes for Mobile IPv4
draft-ietf-mip4-experimental-messages-01.txt
Status of this Memo
This document is an Internet-Draft and is in full conformance
with all provisions of Section 10 of RFC2026.
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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.
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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 Mobile IPv4 Experimental Extension........5
4.2 Non-skippable Router Discovery Experimental 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
8. Security Considerations..................................8
9. Backward Compatibility Considerations....................9
10. Intellectual Property Rights............................9
11. Acknowledgements........................................9
12. References.............................................10
12.1 Normative References..................................10
12.2 Informative References................................10
13. Authors' Addresses.....................................10
Intellectual Property Statement............................11
Full 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.
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 the FA [64-127] and
HA [128-192]. This document reserves an error code in both
these ranges for experimental use.
This document defines and reserves experimental numbers as per
the recommendation of BCP 82 (section 2.2), RFC 3692.
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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].
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
(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
(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 reply messages to indicate 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 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.
These messages may 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]).
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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 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 Mobile IPv4 extensions in both the
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
by [2] are used for Mobile IPv4 experimental extensions.
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Also, ICMP router discovery extension numbers in both the
skippable and non-skippable range 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 bytes.
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 Router Discovery Experimental 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 . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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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,
Sub-Type and Length bytes.
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 bytes.
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.
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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 bytes.
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.
5. Experimental Error Codes
This document reserves reply error code EXP-FA-ERROR-CODE, in
the range [64-127], for use by the FA. This document also
reserves reply error code EXP-HA-ERROR-CODE, in the range [128-
192], for use by the HA.
These experimental error codes may be used in registration
reply messages.
It is recommended that experimental error codes are used
with experimental messages and extensions whenever none of the
standardized error codes are applicable.
6. Mobility Entity Considerations
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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 the Mobile IP control message
space.
Also, values for EXP-NONSKIP-EXT-TYPE and EXP-SKIP-EXT-TYPE
must be assigned for experimental extensions.
The value for EXP-NONSKIP-EXT-TYPE should be assigned from the
numbering space for non-skippable extensions which may appear
in control messages, and also (with the same number) from the
numbering space for non-skippable extensions which may appear
in ICMP router discovery messages. The value 127 is suggested
in both cases.
The value for EXP-SKIP-EXT-TYPE should be assigned from the
numbering space for skippable extensions which may appear in
control messages, and also (with the same number) from the
numbering space for skippable extensions which may appear in
ICMP router discovery messages. The value 255 is suggested in
both cases.
Also, values for EXP-HA-ERROR-CODE and EXP-FA-ERROR-CODE must
be assigned for experimental error code. The suggested values
are 192 for the EXP-HA-ERROR-CODE and 127 for the EXP-FA-ERROR-
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
MUST be discarded.
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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.
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 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.
Copies of IPR disclosures made to the IETF Secretariat 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 implementers or users of
this specification can be obtained from the IETF on-line IPR
repository at http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention
any copyrights, patents or patent applications, or other
proprietary rights that may cover technology that may be
required to implement this standard. Please address the
information to the IETF at ietf-ipr@ietf.org.
11. Acknowledgements
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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.
12. References
12.1 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.
12.2 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
13. 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
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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
Phone: +1 408-526-5030
Intellectual Property Statement
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.
Full Copyright Statement
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