Experimental Codepoint Allocation for the Path Computation Element communication Protocol (PCEP)
draft-ietf-pce-pcep-exp-codepoints-04

Abstract

IANA assigns values to the Path Computation Element (PCE) 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 code points as assigned for Experimental Use.

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Table of Contents

• 1. Introduction
• 2. PCEP Messages
• 3. PCEP Objects
• 4. PCEP TLVs
• 5. Handling of Unknown Experimentation
• 6. IANA Considerations
• 6.1. New PCEP Messages
• 6.2. New PCEP Objects
• 6.3. New PCEP TLVs
• 7. Security Considerations
• 8. Acknowledgments
• 9. References
• 9.1. Normative References
• 9.2. Informative References
• Appendix A. Other PCEP Registries
• Authors' Addresses

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 Clients (PCCs) 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. [I-D.ietf-pce-pce-initiated-lsp] 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 code points, 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 won't collide not only with existing codepoints but any future allocation.

This document updates [RFC5440] by changing the allocation policies for these three registries to mark some of the code points as assigned for Experimental Use. See [RFC3692] for further discussion of the use of experimental codepoints.

2. 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.

3. 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. 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, would react as per section 6.9 of [RFC5440] by sending a PCErr message with Error-value=2 (capability not supported).

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 (PCUpd) Request message).

As per section 7.1 of [RFC5440], unknown experimental PCEP TLV would be ignored.

6. IANA Considerations

IANA maintains the "Path Computation Element Protocol (PCEP) Numbers" at <http://www.iana.org/assignments/pcep>.

6.1. New PCEP Messages

Within this registry IANA maintains a sub-registry for PCEP Messages (see PCEP Messages at <http://www.iana.org/assignments/pcep>).

   0-251   IETF Review
   252-255 Experimental Use
   

IANA is requested to change the registration procedure for this registry to read as follows:

IANA is also requested to mark the values 252-255 in the registry accordingly.

6.2. New PCEP Objects

Within this registry IANA maintains a sub-registry for PCEP Objects (see PCEP Objects at <http://www.iana.org/assignments/pcep>).

   0-247   IETF Review
   248-255 Experimental Use
   

IANA is requested to change the registration procedure for this registry to read as follows:

IANA is also requested to mark the values 248-255 in the registry accordingly.

6.3. New PCEP TLVs

Within this registry IANA maintains a sub-registry for PCEP TLVs (see PCEP TLV Type Indicators at <http://www.iana.org/assignments/pcep>).

   0-65503     IETF Review
   65504-65535 Experimental Use

IANA is requested to change the registration procedure for this registry to read as follows:

IANA is also requested to mark 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 code points 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.

8. Acknowledgments

The authors would like to thank Ramon Casellas, Jeff Tantsura, Julien Mueric, 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.

9. References

9.1. Normative References

9.2. Informative References

Appendix A. Other PCEP Registries

Based on feedback from the PCE WG, it was decided to allocate an Experimental code point 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 code point in another PCEP sub-registry, it can implement the same function using a new experimental object or TLV instead.

Authors' Addresses