Network Working Group George Swallow
Internet Draft Cisco Systems, Inc.
Category: Standards Track
Expiration Date: September 2007
Updates RFC2205, RFC3473 Adrian Farrel
Old Dog Consulting
March 2007
User Defined Errors for RSVP
draft-swallow-rsvp-user-error-spec-01.txt
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Abstract
The Resource ReserVation Protocol (RSVP) defines an ERROR_SPEC object
for communicating errors. That object has a defined format that
permits the definition of 256 error codes. As RSVP has been
developed and extended, the convention has been to be conservative in
defining new error codes. Further, no provision for user defined
errors exists in RSVP.
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Internet Draft draft-swallow-rsvp-user-error-spec-01.txt March 2007
This document defines a new RSVP object to permit user defined error
values to be communicated.
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Contents
1 Introduction .............................................. 4
1.1 Conventions ............................................... 4
2 User Defined Error ........................................ 4
3 USER_ERROR_SPEC Class ..................................... 5
3.1 Subobjects ................................................ 6
4 Procedures for using the User Error Spec .................. 7
4.1 Procedures for sending the User Error Spec ................ 7
4.2 Procedures for receiving the User Error Spec .............. 7
5 IANA Considerations ....................................... 7
6 Security Considerations ................................... 8
7 Acknowledgments ........................................... 8
8 Normative References ...................................... 8
9 Authors' Addresses ........................................ 9
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1. Introduction
The Resource ReserVation Protocol (RSVP) [RFC2205] defines an
ERROR_SPEC object for communicating errors. That object has a
defined format that permits the definition of 256 error codes. As
RSVP has been developed and extended, the convention has been to be
conservative in communicating errors. Further no provision for user
defined errors exists in RSVP.
When developing extensions to RSVP, it is often useful for those
implementing to define error messages to aid both in the initial
debugging and in testing against older versions or other implementa-
tions.
This document defines a new RSVP object to permit user defined errors
to be communicated. This will enable organizations to define errors
which they can use for internal development. These error values
could also be shared with the community at large to aid in promoting
interoperability between diverse implementations.
RSVP PathErr and ResvErr messages require the presence of an
ERROR_SPEC object. [RFC3473] defines the Notify message that also
requires the presence of an ERROR_SPEC object. In order to not
change the mandatory contents of these messages, this document
defines a new error code value that indicates that the new object is
present and carries a user defined error code.
1.1. Conventions
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 [KEYWORDS].
2. User Defined Error
Error Code = <tba>: User Error Spec
This error code is used to signal the presence of a
USER_ERROR_SPEC. No subcodes are defined.
When sending this error code, a USER_ERROR_SPEC object MUST be
included in the PathErr, ResvErr or Notify message.
[Editor's note: <tba> = to be assigned by IANA]
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3. USER_ERROR_SPEC Class
A new RSVP object class is defined called the the USER_ERROR_SPEC
Class. The class number is taken from the range 192 - 247. This is
done for backward compatibility. Existing implementations will
ignore the object and pass it along.
USER_ERROR_SPEC object: Class = <tba>, C-Type = 1
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
+---------------+---------------+---------------+---------------+
| Enterprise Number |
+---------------+---------------+---------------+---------------+
| Sub Org | Err Desc Len | User Error Value |
+---------------+---------------+---------------+---------------+
| |
. Error Description .
. .
| |
+---------------+---------------+---------------+---------------+
| |
. User Defined Subobjects .
. .
| |
+---------------+---------------+---------------+---------------+
Enterprise Number
A unique identifier of an organization encoded as a 32-bit
integer. Enterprise Numbers are assigned by IANA.
Sub-organization
A unique identifier of an organization encoded as a 8-bit
integer. An organization MAY use this field to create
independent Error Value spaces. This is intended to
facilitate teams which are doing parallel development. If
independent spaces are not required, this field SHOULD be
set to zero.
Err Desc Len
The length of the error description in the Error Description
field in buyes excluding any padding.
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User Error Value
A 16-bit integer The format and contents are specified by
the (sub-)organization indicated by the Enterprise Number
and Sub Org fields.
Error Description
A string of characters in US-ASCII padded with nulls (0x00)
to a multiple of 4 bytes. While no format is required, it
is RECOMMENDED that organizations use a published schema for
this string to promote consistent decoding.
User Defined Subobjects
Optionally, user defined subobjects may be included. The
semantics of the Type and the format and contents of the
value are specified by the (sub-) organization indicated
by the Enterprise Number and Sub Org fields.
3.1. Subobjects
Each subobject is encoded as a TLV in the following format:
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------//----------------+
| Type | Length | (Subobject contents) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------//----------------+
Type
An 8-bit number assigned by the the (sub-) organization
indicated by the Enterprise Number and Sub Org fields.
Length
The Length contains the total length of the Subobject contents
in bytes, including the L, Type and Length fields. The Length
MUST be at least 4, and MUST be a multiple of 4.
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4. Procedures for using the User Error Spec
4.1. Procedures for sending the User Error Spec
A USER_ERROR_SPEC object MAY be included in any PathErr, ResvErr or
Notify message. The Enterprise Number MUST be a valid value assigned
by IANA. As specified in [RFC2205] and [RFC3473], an ERROR_SPEC
object with a valid error code MUST be included in those messages.
If no other error code applies, the error code MUST be set to <tba>,
Unspecified Error.
4.2. Procedures for receiving the User Error Spec
It is RECOMMENDED that implementations at a minimum log the Enter-
prise Number Sub-organization, User Error Value, and Error Descrip-
tion. Implementation capable of interpreting the contents of the
USER_ERROR_SPEC object SHOULD take appropriate action.
If a message is received containing an ERROR_SPEC object using the
"User Error Spec" error code, but not containing a USER_ERROR_SPEC
object, the message SHOULD be treated as malformed and handled
according to [RFC2205].
Implementations SHOULD ignore repeated occurences of USER_ERROR_SPEC
objects.
5. IANA Considerations
This document makes the following assignments from the RSVP Error
Codes and Globally-Defined Error Value Sub-Codes registry (pending
IANA action):
Value Name
<tba> User Error Spec
This document makes the following assignments from the RSVP Class
Names, Class Numbers, and Class Types registry (pending IANA action):
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Number Space Value Name
Class Numbers <tba>* User Error Spec
Class Type 1 User Defined Error
* Assignment is requested from the range 192 through 247
6. Security Considerations
This document makes no changes to the basic message exchanges of
[RFC2205] and [RFC3473]. It will result in a small increase in the
number of error messages sent in cases where messages were silently
dropped due to the lack of an appropriate error code.
7. Acknowledgments
The authors would like to thank Elisheva Halevy for motivating this
document and Tom Nadeau for his review and comments.
8. Normative References
[RFC2205] Braden, R., Zhang, L., Berson, S., Herzog, S., and S. Jamin,
"Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
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9. Authors' Addresses
George Swallow
Cisco Systems, Inc.
Email: swallow@cisco.com
Adrian Farrel
Old Dog Consulting
EMail: adrian@olddog.co.uk
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Internet Draft draft-swallow-rsvp-user-error-spec-01.txt March 2007
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