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LSP Object Flag Extension of Stateful PCE
draft-ietf-pce-lsp-extended-flags-01

The information below is for an old version of the document.
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This is an older version of an Internet-Draft that was ultimately published as RFC 9357.
Expired & archived
Author Quan Xiong
Last updated 2022-04-21 (Latest revision 2021-10-18)
Replaces draft-xiong-pce-lsp-flag
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draft-ietf-pce-lsp-extended-flags-01
PCE                                                             Q. Xiong
Internet-Draft                                           ZTE Corporation
Intended status: Standards Track                            October 2021
Expires: 20 April 2022

               LSP Object Flag Extension of Stateful PCE
                  draft-ietf-pce-lsp-extended-flags-01

Abstract

   RFC 8231 describes a set of extensions to Path Computation Element
   Communication Protocol (PCEP) to enable stateful control of MPLS-TE
   and GMPLS Label Switched Paths(LSPs) via PCEP.  One of the extensions
   is the LSP object which includes a Flag field of the length of 12
   bits.  However, 11 bits of the Flag field have already been assigned
   in RFC 8231, RFC 8281 and RFC 8623.

   This document proposes to define a new LSP-EXTENDED-FLAG TLV for the
   LSP object for an extended flag field.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 4 April 2022.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components

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   extracted from this document must include Simplified BSD License text
   as described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions used in this document . . . . . . . . . . . . . .   3
     2.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   3.  PCEP Extension  . . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  The LSP-EXTENDED-FLAG TLV . . . . . . . . . . . . . . . .   3
     3.2.  Processing  . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Backward Compatibility  . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
     5.1.  LSP Object  . . . . . . . . . . . . . . . . . . . . . . .   4
       5.1.1.  PCEP TLV Type Indicators  . . . . . . . . . . . . . .   5
       5.1.2.  LSP Extended Flags Field  . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   8.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   5
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   [RFC5440] describes the Path Computation Element Protocol (PCEP)
   which is used between a Path Computation Element (PCE) and a Path
   Computation Client (PCC) (or other PCE) to enable computation of
   Multi-protocol Label Switching (MPLS) for Traffic Engineering Label
   Switched Path (TE LSP).

   PCEP Extensions for the Stateful PCE Model [RFC8231] describes a set
   of extensions to PCEP to enable active control of MPLS-TE and
   Generalized MPLS (GMPLS) tunnels.  One of the extensions is the LSP
   object which contains a flag field; bits in the flag field are used
   to indicate delegation, syncronization, removal, etc.

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   As defined in [RFC8231], the length of the flag field is 12 bits and
   the value from bit 5 to bit 11 is used for operational,
   administrative, remove, synchronize and delegate bits respectively.
   The bit value 4 is assigned in [RFC8281] for create for PCE-Initiated
   LSPs.  The bits from 1 to 3 is assigned in [RFC8623] for Explicit
   Route Object (ERO)-compression, fragmentation and Point-to-Multipoint
   (P2MP) respectively.  Almost all bits of the Flag field has been
   assigned already.  Thus, it is required to extend the flag field for
   the LSP Object for future use.

   This document proposes to define a new LSP-EXTENDED-FLAG TLV for an
   extended flag field in the LSP object.

2.  Conventions used in this document

2.1.  Terminology

   The terminology is defined as [RFC5440] and [RFC8231].

2.2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  PCEP Extension

   The LSP Object is defined in Section 7.3 of [RFC8231].  This document
   proposes to define a new LSP-EXTENDED-FLAG TLV for an extended flag
   field in the LSP object.

3.1.  The LSP-EXTENDED-FLAG TLV

   The format of the LSP-EXTENDED-FLAG TLV is as shown in the Figure 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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |           Type=TBD            |          Length               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     //                 LSP Extended Flags                          //
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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              Figure 1: Figure 1: LSP-EXTENDED-FLAG TLV Format

   Type (16 bits): the value is TBD1 by IANA.

   Length (16 bits): multiple of 4 octets.

   LSP Extended Flags: this contains an array of units of 32-bit flags
   numbered from the most significant as bit zero, where each bit
   represents one LSP operation, feature, or state.  Currently no bits
   are assigned.  Unassigned bits MUST be set to zero on transmission
   and MUST be ignored on receipt.  For example of usage of the LSP-
   EXTENDED-FLAG TLV, the E-flag is requested for entropy label
   configuration proposed in [I-D.peng-pce-entropy-label-position].

3.2.  Processing

   The LSP Extended Flags field is an array of units of 32 flags and to
   be allocated starting from the most significant bit.  No bits are
   currently assigned in this document and the bits of the LSP Extended
   Flags field will be assigned by future documents.

   Note that, PCEP peers MAY encounter different length of the LSP-
   EXTENDED-FLAG TLV.

   If a PCEP speaker receives the LSP-EXTENDED-FLAG TLV of a length more
   than it currently supports or understands, it will simply ignore the
   bits beyond that length.

   If a PCEP speaker receives the LSP-EXTENDED-FLAG TLV of a length less
   than the one supported by the implementation, it will consider the
   bits beyond the length to be unset.

4.  Backward Compatibility

   The LSP-EXTENDED-FLAG TLV defined in this document does not introduce
   any interoperability issues.

   A router that does not understand or support the LSP-EXTENDED-FLAG
   TLV will silently ignore the TLV as per [RFC5440].  It is expected
   that future document that define bits in the LSP-EXTENDED-FLAG TLV
   would also define the error case handling required for missing LSP-
   EXTENDED-FLAG TLV.

5.  IANA Considerations

5.1.  LSP Object

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5.1.1.  PCEP TLV Type Indicators

   IANA is requested to allocate the following TLV Type Indicator value
   within the "PCEP TLV Type Indicators" subregistry of the "Path
   Computation Element Protocol (PCEP) Numbers" registry:

              +=======+===================+=================+
              | Value | Description       | Reference       |
              +=======+===================+=================+
              | TBD1  | LSP-EXTENDED-FLAG | [This document] |
              +-------+-------------------+-----------------+

                                  Table 1

5.1.2.  LSP Extended Flags Field

   IANA is requested to create a new subregistry called "LSP-EXTENDED-
   FLAG TLV Flag Field", within the "Path Computation Element Protocol
   (PCEP) Numbers" registry to manage the LSP Extended Flags field of
   the LSP-EXTENDED-FLAG TLV.  New values are assigned by Standards
   Action [RFC8126].  Each bit should be tracked with the following
   qualities:

   *  Bit number (counting from bit 0 as the most significant bit)

   *  Capability description

   *  Defining RFC

   No values are currently defined.

6.  Security Considerations

   For LSP Object procssing security considerations, see [RFC8231].

   No additional security issues are raised in this document beyond
   those that exist in the referenced documents.

7.  Acknowledgements

   The authors would like to thank Loa Andersson and Adrian Farrel for
   their review, suggestions and comments to this document.

8.  Contributors

   The following people have contributed to this document:

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   Dhruv Dhody

   EMail: dhruv.ietf@gmail.com

9.  References

9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [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>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [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>.

9.2.  Informative References

   [I-D.peng-pce-entropy-label-position]
              Xiong, Q., Peng, S., and F. Qin, "PCEP Extension for SR-
              MPLS Entropy Label Position", Work in Progress, Internet-
              Draft, draft-peng-pce-entropy-label-position-06, 7 July
              2021, <https://www.ietf.org/archive/id/draft-peng-pce-
              entropy-label-position-06.txt>.

   [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>.

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   [RFC8623]  Palle, U., Dhody, D., Tanaka, Y., and V. Beeram, "Stateful
              Path Computation Element (PCE) Protocol Extensions for
              Usage with Point-to-Multipoint TE Label Switched Paths
              (LSPs)", RFC 8623, DOI 10.17487/RFC8623, June 2019,
              <https://www.rfc-editor.org/info/rfc8623>.

Author's Address

   Quan Xiong
   ZTE Corporation
   No.6 Huashi Park Rd
   Wuhan
   Hubei, 430223
   China

   Email: xiong.quan@zte.com.cn

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