User-Defined Errors for RSVP
draft-ietf-tsvwg-rsvp-user-error-spec-08
The information below is for an old version of the document that is already published as an RFC.
| Document | Type | RFC Internet-Draft (tsvwg WG) | |
|---|---|---|---|
| Authors | Adrian Farrel , George Swallow | ||
| Last updated | 2018-12-20 (Latest revision 2008-05-31) | ||
| Replaces | draft-swallow-rsvp-user-error-spec | ||
| Stream | Internet Engineering Task Force (IETF) | ||
| Formats | plain text htmlized pdfized bibtex | ||
| Reviews | |||
| Stream | WG state | (None) | |
| Document shepherd | (None) | ||
| IESG | IESG state | RFC 5284 (Proposed Standard) | |
| Consensus boilerplate | Unknown | ||
| Telechat date | (None) | ||
| Responsible AD | Magnus Westerlund | ||
| Send notices to | (None) |
draft-ietf-tsvwg-rsvp-user-error-spec-08
Network Working Group G. Swallow
Internet-Draft Cisco Systems, Inc.
Category: Standards Track
Created: May 31, 2008 A. Farrel
Expiration Date: November 31, 2008 Old Dog Consulting
User-Defined Errors for RSVP
draft-ietf-tsvwg-rsvp-user-error-spec-08.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.
This document defines a USER_ERROR_SPEC to be used in addition to the
ERROR_SPEC to carry additional user information related to errors.
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draft-ietf-tsvwg-rsvp-user-error-spec-08.txt May 2008
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
implementations.
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 ([RFC2205]). [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.
Note that the ResvConf message defined in [RFC2205] also carries an
ERROR_SPEC object. But this usage of the object does not carry
meaningful Error Codes or Error Values and so the extensions defined
in this document are not applicable to that message.
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 [RFC2119].
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2. User-Defined Error
A new Error Code is defined for use in an ERROR_SPEC object.
Error Code = <tba-xxx>: User Error Spec
This error code is used to signal the presence of a
USER_ERROR_SPEC. One Error Value is defined as follows.
Error Value 0 = Further details in User Error Spec
Further error values may be defined in future specifications.
When sending this error code, a USER_ERROR_SPEC object MUST be
included in the PathErr, ResvErr, or Notify message.
[RFC Editor's note: <tba-xxx> = to be assigned by IANA as per Section 5.
Please replace <tba-xxx> with the number assigned by IANA and remove
this note.]
3. USER_ERROR_SPEC Class
A new RSVP object class called USER_ERROR_SPEC is defined. To support
backwards compatibility, its class number is in the range 192-247. As
defined in [RFC2205], implementations that do not understand such an
object will forward it unmodified.
USER_ERROR_SPEC object: Class = <tba-yyy>, C-Type = 1
[RFC Editor's note: <tba-yyy> = to be assigned by IANA as per Section 5.
Please replace <tba-yyy> with the number assigned by IANA and remove
this note.]
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 ~
| |
+---------------+---------------+---------------+---------------+
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Enterprise Number
A unique identifier of an organization encoded as a 32-bit
integer. Enterprise Numbers (sometimes known as Private
Enterprise Numbers) are assigned by IANA and managed on a first
come first served basis through the IANA registry named
"Enterprise Numbers" [RFC2578].
Sub Org
A unique identifier of an organization encoded as an 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 bytes excluding any padding. Zero is a valid length if
no error description is supplied.
User Error Value
A 16-bit integer. The meaning is specified by the
(sub-)organization indicated by the Enterprise Number and Sub
Org fields.
Error Description
A string of characters padded with nulls (0x00) to a multiple of
4 bytes. According to the guidance in [RFC2277], this string
MUST use UTF-8/Net-Unicode encoding [RFC5198]. Furthermore, it
is RECOMMENDED that implementations limit the strngs that they
generate to single-line printable US-ASCII [ASCII] whenever
feasible to improve the likelihood of easy use by the recipient.
If the Err Desc Len is zero then no bytes are supplied.
Note that the content of this field is implementation-specific.
It is typically printable, but might not be shown to all users
in all implementations (because of character set choice).
Therefore, the content of the field SHOULD be limited to
supplementary information and SHOULD NOT contain information
critical to operating the network. Criticial information is
present in the User Error Value field.
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User-Defined Subobjects
User-defined subobjects MAY be included. The generic format of
subobjects is specified in Section 3.1. The semantics of a
subobject is indicated by the Type field, but the semantics,
format and contents of the Value field are specified by the
(sub-)organization indicated by the Enterprise Number and
Sub Org fields of this object.
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 of the
USER_ERROR_SPEC object.
Length
The Length contains the total length of the subobject in bytes,
including the Type and Length fields. The Length MUST be at
least 4, and MUST be a multiple of 4.
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 for any defined error code. The Enterprise Number
MUST be a valid value assigned by IANA from the "Enterprise Numbers"
registry.
As specified in [RFC2205] and [RFC3473], an ERROR_SPEC object with a
valid error code MUST be included in all PathErr, ResvErr, and Notify
messages. This rule is not changed by these procedures even when a
USER_ERROR_SPEC object is included. If no other error code applies,
the Error Code in the ERROR_SPEC object MUST be set to "User Error
Spec" as defined in Section 2 of this document. When the Error Code
in the ERROR_SPEC object is set to "User Error Spec", the Error Value
sub-code SHOULD be set to "Further details in User Error Spec" as
defined in Section 2, but further Error Value sub-codes may be
defined in future specifications.
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4.2. Procedures for Receiving the User Error Spec
It is RECOMMENDED that implementations that receive a PathErr,
ResvErr, or Notify message carrying a USER_ERROR_SPEC object at a
minimum log the Enterprise Number, Sub-organization, User Error
Value, and Error Description. Note that the character set used for
the Error Description may mean that it might not be suitable for
display of logging in all systems. Implementations capable of
interpreting the contents of the USER_ERROR_SPEC object SHOULD take
further action based on the reported error.
Implementations that are not UTF-8 capable that receive a
USER_ERROR_SPEC object SHOULD handle the Error Descriprion according
to the procedures set out in [RFC5137].
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 MUST be treated as malformed and handled
according to [RFC2205].
Implementations SHOULD ignore repeated occurences of USER_ERROR_SPEC
objects, and SHOULD forward them unchanged on any messages that they
forward. This provides for forward compatiblity.
Implementations receiving a USER_ERROR_SPEC object on some message
other than a PathErr, ResvErr, or Notify message MUST treat the
error as a malformed message and process according to [RFC2205].
5. IANA Considerations
5.1. RSVP Error Codes
This document makes the following assignments from the RSVP Error
Codes and Globally-Defined Error Value Sub-Codes registry (pending
IANA action):
Error Code Meaning
<tba-xxx> User Error Spec
One Error Value sub-code is defined for use with this Error Code as
follows:
0 = Further details in User Error Spec
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5.2. RSVP Objects
This document makes the following assignments from the RSVP Class
Names, Class Numbers, and Class Types registry (pending IANA action):
Number Space Value Name
Class Numbers <tba-yyy>* 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 previously
silently dropped due to the lack of an appropriate error code.
The mechanisms defined in this document may be used by
implementations to report additional error conditions and information
arising from security issues and attacks on the RSVP network.
Note that the use of a character string that will be displayed or
logged opens the potential for certain security attacks through the
use of overruns or embedded control characters. Implementations
SHOULD take precautions against overruns, and (especially where the
full characterset of [RFC5198] is not supported, SHOULD use the
procedures set out in [RFC5137] to handle unexpected or unknown
control characters.
7. Acknowledgments
The authors would like to thank Elisheva Halevy for motivating this
document. Thanks to Tom Nadeau, Magnus Westerlund, Hannes Tschofenig,
Bruce Davie, Jukka Manner, Francois Le Faucheur, Lars Eggert, and Tom
Petch for their review and comments.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2205] Braden, R., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997.
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[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
[RFC5137] Klensin, J., "ASCII Escaping of Unicode Characters",
RFC 5137, BCP 137, February 2008.
[RFC5198] Klensin, J., and Padlipsky, M., "Unicode Format for
Network Interchange", RFC 5198, March 2008.
[ASCII] American National Standards Institute, "USA Code for
Information Interchange", ANSI X3.4, 1968.
8.2. Informative References
[RFC2277] Alvestrand, H., "IETF Policy on Character Sets and
Languages", RFC 2277, BCP 18, January 1998.
[RFC2578] McCloghrie, K., Perkins, D., and J. Schoenwaelder,
"Structure of Management Information Version 2 (SMIv2)",
STD 58, RFC 2578, April 1999.
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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