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User-Defined Errors for RSVP

The information below is for an old version of the document that is already published as an RFC.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 5284.
Authors Adrian Farrel , George Swallow
Last updated 2018-12-20 (Latest revision 2008-05-31)
Replaces draft-swallow-rsvp-user-error-spec
RFC stream Internet Engineering Task Force (IETF)
Intended RFC status Proposed Standard
Additional resources Mailing list discussion
Stream WG state (None)
Document shepherd (None)
IESG IESG state Became RFC 5284 (Proposed Standard)
Action Holders
Consensus boilerplate Unknown
Telechat date (None)
Responsible AD Magnus Westerlund
Send notices to (None)
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


Status of this Memo

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   applicable patent or other IPR claims of which he or she is aware
   have been or will be disclosed, and any of which he or she becomes
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   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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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

   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",
   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.]


   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                   ~
     |                                                               |

Swallow & Farrel             Standards Track                    [Page 3]
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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)          |


        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.


        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"

   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.

Swallow & Farrel             Standards Track                    [Page 5]
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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

         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.

   Adrian Farrel
   Old Dog Consulting

10. Intellectual Property

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   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

Swallow & Farrel             Standards Track                    [Page 8]
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   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-

Full Copyright Notice

   Copyright (C) The IETF Trust (2008).  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.

   This document and the information contained herein are provided on an

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