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PROPOSED STANDARD
Internet Engineering Task Force (IETF) D. Dhody
Request for Comments: 8356 Huawei Technologies
Updates: 5440 D. King
Category: Standards Track Lancaster University
ISSN: 2070-1721 A. Farrel
Juniper Networks
March 2018
Experimental Codepoint Allocation for
the Path Computation Element Communication Protocol (PCEP)
Abstract
IANA assigns values to the Path Computation Element Communication
Protocol (PCEP) parameters (messages, objects, TLVs). IANA
established a top-level registry to contain all PCEP codepoints and
sub-registries. This top-level registry contains sub-registries for
PCEP message, object, and TLV types. The allocation policy for each
of these sub-registries is IETF Review.
This document updates RFC 5440 by changing the allocation policies
for these three registries to mark some of the codepoints as assigned
for Experimental Use.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8356.
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Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Experimental PCEP Messages . . . . . . . . . . . . . . . . . 3
3. Experimental PCEP Objects . . . . . . . . . . . . . . . . . . 4
4. Experimental PCEP TLVs . . . . . . . . . . . . . . . . . . . 4
5. Handling of Unknown Experimentation . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
6.1. PCEP Messages . . . . . . . . . . . . . . . . . . . . . . 4
6.2. PCEP Objects . . . . . . . . . . . . . . . . . . . . . . 5
6.3. PCEP TLVs . . . . . . . . . . . . . . . . . . . . . . . . 5
7. Security Considerations . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . 6
Appendix A. Other PCEP Registries . . . . . . . . . . . . . . . 7
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
The Path Computation Element Communication Protocol (PCEP) [RFC5440]
provides mechanisms for Path Computation Elements (PCEs) to perform
path computations in response to Path Computation Client (PCC)
requests.
Further, in order to support use cases described in [RFC8051],
[RFC8231] specifies a set of extensions to PCEP to enable stateful
control of MPLS-TE and GMPLS LSPs via PCEP. [RFC8281] describes the
setup, maintenance, and teardown of PCE-initiated LSPs under the
stateful PCE model.
In Section 9 of [RFC5440], IANA assigns values to the PCEP protocol
parameters (messages, objects, TLVs). IANA established a top-level
registry to contain all PCEP codepoints and sub-registries. This
top-level registry contains sub-registries for PCEP message, object
and TLV types. The allocation policy for each of these sub-
registries is IETF Review [RFC8126]. Also, early allocation
[RFC7120] provides some latitude for allocation of these codepoints
but is reserved for features that are considered appropriately
stable.
Recently, there have been rapid advancements in PCE technology, which
has created an enhanced need to experiment with PCEP. It is often
necessary to use some sort of number or constant in order to actually
test or experiment with the new function, even when testing in a
closed environment. In order to run experiments, it is important
that the value not collide with existing codepoints or any future
allocations.
This document updates [RFC5440] by changing the allocation policies
for these three registries to mark some of the codepoints as assigned
for Experimental Use. As stated in [RFC3692], experiments using
these codepoints are not intended to be used in general deployments,
and due care must be taken to ensure that two experiments using the
same codepoints are not run in the same environment. See [RFC3692]
for further discussion of the use of experimental codepoints (also
referred to as "experimental and testing numbers").
2. Experimental PCEP Messages
PCEP message types are in the range 0 to 255. This document sets
aside message types 252-255 for experimentation as described in
Section 6.1.
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3. Experimental PCEP Objects
PCEP objects are identified by values in the range 0 to 255. This
document sets aside object identifiers 248-255 for experimentation as
described in Section 6.2.
4. Experimental PCEP TLVs
PCEP TLV type codes are in the range 0 to 65535. This document sets
aside object identifiers 65504-65535 for experimentation as described
in Section 6.2.
5. Handling of Unknown Experimentation
A PCEP implementation that receives an experimental PCEP message that
it does not recognize reacts by sending a PCErr message with
Error-Type=2 (capability not supported) per Section 6.9 of [RFC5440].
If a PCEP speaker does not understand or support an experimental
object, then the way it handles this situation depends on the message
type. For example, a PCE handles an unknown object in the Path
Computation Request (PCReq) message according to the rules of
[RFC5440]. Message-specific behavior may be specified (e.g.,
[RFC8231] defines rules for a PCC to handle an unknown object in a
Path Computation LSP Update Request (PCUpd) message).
As per Section 7.1 of [RFC5440], an unknown experimental PCEP TLV
would be ignored.
6. IANA Considerations
IANA maintains the "Path Computation Element Protocol (PCEP) Numbers"
registry at <http://www.iana.org/assignments/pcep>.
6.1. PCEP Messages
Within the PCEP Numbers registry, IANA maintains the "PCEP Messages"
sub-registry.
IANA has changed the registration procedure for this registry to read
as follows:
0-251 IETF Review
252-255 Experimental Use
IANA has also marked the values 252-255 in the registry accordingly.
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6.2. PCEP Objects
Within the PCEP Numbers registry, IANA maintains the "PCEP Objects"
sub-registry.
IANA has changed the registration procedure for this registry to read
as follows:
0-247 IETF Review
248-255 Experimental Use
IANA has also marked the values 248-255 in the registry accordingly,
and Object-Types 0-15 have been marked for Experimental Use.
6.3. PCEP TLVs
Within the PCEP Numbers registry, IANA maintains the "PCEP TLV Type
Indicators" sub-registry.
IANA has changed the registration procedure for this registry to read
as follows:
0-65503 IETF Review
65504-65535 Experimental Use
IANA has also marked the values 65504-65535 in the registry
accordingly.
7. Security Considerations
This document does not introduce any new security considerations to
the existing protocol. Refer to [RFC5440] for further details of the
specific security measures.
[RFC3692] asserts that the existence of experimental codepoints
introduce no new security considerations. However, implementations
accepting experimental codepoints need to take care in how they parse
and process the messages, objects, and TLVs in case they come,
accidentally, from another experiment. Further, an implementation
accepting experimental codepoints needs to consider the security
aspects of the experimental extensions. [RFC6709] provides various
design considerations for protocol extensions (including those
designated as experimental).
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8. References
8.1. Normative References
[RFC3692] Narten, T., "Assigning Experimental and Testing Numbers
Considered Useful", BCP 82, RFC 3692,
DOI 10.17487/RFC3692, January 2004,
<https://www.rfc-editor.org/info/rfc3692>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path
Computation Element Communication Protocol (PCEP)
Extensions for Stateful PCE", RFC 8231,
DOI 10.17487/RFC8231, September 2017,
<https://www.rfc-editor.org/info/rfc8231>.
[RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path
Computation Element Communication Protocol (PCEP)
Extensions for PCE-Initiated LSP Setup in a Stateful PCE
Model", RFC 8281, DOI 10.17487/RFC8281, December 2017,
<https://www.rfc-editor.org/info/rfc8281>.
8.2. Informative References
[RFC6709] Carpenter, B., Aboba, B., Ed., and S. Cheshire, "Design
Considerations for Protocol Extensions", RFC 6709,
DOI 10.17487/RFC6709, September 2012,
<https://www.rfc-editor.org/info/rfc6709>.
[RFC7120] Cotton, M., "Early IANA Allocation of Standards Track Code
Points", BCP 100, RFC 7120, DOI 10.17487/RFC7120, January
2014, <https://www.rfc-editor.org/info/rfc7120>.
[RFC8051] Zhang, X., Ed. and I. Minei, Ed., "Applicability of a
Stateful Path Computation Element (PCE)", RFC 8051,
DOI 10.17487/RFC8051, January 2017,
<https://www.rfc-editor.org/info/rfc8051>.
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Appendix A. Other PCEP Registries
Based on feedback from the PCE WG, it was decided to allocate an
Experimental codepoint range only in the message, object, and TLV
sub-registries. The justification for this decision is that, if an
experiment finds that it wants to use a new codepoint in another PCEP
sub-registry, it can implement the same function using a new
experimental object or TLV instead.
Acknowledgments
The authors would like to thank Ramon Casellas, Jeff Tantsura, Julien
Meuric, Lou Berger, Michael Shroff, and Andrew Dolganow for their
feedback and suggestions.
We would like to thank Jonathan Hardwick for shepherding this
document and providing comments with text suggestions.
Thanks to Brian Carpenter for the GENART review. Thanks to Ben
Niven-Jenkins and Scott Bradner for RTGDIR and OPSDIR reviews
respectively.
Authors' Addresses
Dhruv Dhody
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
EMail: dhruv.ietf@gmail.com
Daniel King
Lancaster University
United Kingdom
EMail: d.king@lancaster.ac.uk
Adrian Farrel
Juniper Networks
United Kingdom
EMail: afarrel@juniper.net
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