Path Computation Element Communication Protocol (PCEP) extensions for Circuit Style Policies
draft-ietf-pce-circuit-style-pcep-extensions-09

PCE Working Group                                               S. Sidor
Internet-Draft                                       Cisco Systems, Inc.
Intended status: Standards Track                           P. Maheshwari
Expires: 28 December 2025                                   Airtel India
                                                                A. Stone
                                                                   Nokia
                                                                L. Jalil
                                                                 Verizon
                                                                 S. Peng
                                                     Huawei Technologies
                                                            26 June 2025

 Path Computation Element Communication Protocol (PCEP) extensions for
                         Circuit Style Policies
            draft-ietf-pce-circuit-style-pcep-extensions-09

Abstract

   Segment Routing (SR) enables a node to steer packet flows along a
   specified path without the need for intermediate per-path states, due
   to the utilization of source routing.  An SR Policy comprises a
   sequence of segments, which are essentially instructions that define
   a source-routed policy

   This document proposes a set of extensions to the Path Computation
   Element Communication Protocol (PCEP) for Segment Routing Policies
   that are designed to satisfy requirements for connection-oriented
   transport services (Circuit-Style SR policies).  They include the
   ability to control path recomputation and the option to request path
   with strict hops only and are also applicable for generic SR policy
   use cases where controlling path recomputation or distinct hop
   requirements are applicable.

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."

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   This Internet-Draft will expire on 28 December 2025.

Copyright Notice

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   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Overview of Extensions to PCEP  . . . . . . . . . . . . . . .   4
     3.1.  New Flags in STATEFUL-PCE-CAPABILITY TLV  . . . . . . . .   4
     3.2.  New Flag in the LSP-EXTENDED-FLAG TLV . . . . . . . . . .   4
     3.3.  PATH-RECOMPUTATION TLV  . . . . . . . . . . . . . . . . .   4
   4.  Operation . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     4.1.  Strict Path Enforcement . . . . . . . . . . . . . . . . .   5
     4.2.  Path Recomputation  . . . . . . . . . . . . . . . . . . .   6
   5.  Manageability Considerations  . . . . . . . . . . . . . . . .   7
     5.1.  Control of Function and Policy  . . . . . . . . . . . . .   7
     5.2.  Information and Data Models . . . . . . . . . . . . . . .   7
     5.3.  Liveness Detection and Monitoring . . . . . . . . . . . .   7
     5.4.  Verify Correct Operations . . . . . . . . . . . . . . . .   7
     5.5.  Requirements On Other Protocols . . . . . . . . . . . . .   8
     5.6.  Impact On Network Operations  . . . . . . . . . . . . . .   8
   6.  Implementation Status . . . . . . . . . . . . . . . . . . . .   8
     6.1.  Cisco . . . . . . . . . . . . . . . . . . . . . . . . . .   8
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
     8.1.  STATEFUL-PCE-CAPABILITY . . . . . . . . . . . . . . . . .   9
     8.2.  LSP-EXTENDED-FLAG TLV . . . . . . . . . . . . . . . . . .  10
     8.3.  PATH-RECOMPUTATION TLV  . . . . . . . . . . . . . . . . .  10
     8.4.  PATH-RECOMPUTATION TLV Flag Field . . . . . . . . . . . .  10
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  12
   Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

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1.  Introduction

   Segment Routing (SR) leverages the source routing paradigm, where the
   sender of a packet defines the path that the packet takes through the
   network.  This is achieved by encoding the path information as a
   sequence of segments within the packet header.  SR can be applied to
   both MPLS and IPv6 data planes, providing a flexible and scalable
   method for traffic engineering.

   The Path Computation Element (PCE) is a network component,
   application, or node that is capable of computing a network path or
   route based on a network graph and applying computational
   constraints.  The PCE Communication Protocol (PCEP) enables
   communication between a PCE and Path Computation Clients (PCCs),
   facilitating the computation of optimal paths for traffic flows.

   [RFC8664] introduces the concept of Segment Routing Policy (SR
   Policy), which is a set of candidate paths that can be used to steer
   traffic through a network.  Each candidate path is represented by a
   list of segments, and the path can be dynamically adjusted based on
   network conditions and requirements.

   In connection-oriented transport services, such as those defined in
   [I-D.ietf-spring-cs-sr-policy], there is a need for path persistency
   and per-hop behavior for PCE-computed paths.  This ensures that the
   paths remain stable and predictable, which is crucial for services
   that require high reliability and performance guarantees.

   To support the requirements of connection-oriented transport
   services, this document specifies extensions to PCEP to enable the
   use of Circuit Style Policies.  These extensions allow for the
   request of strict paths from the PCE, the encoding of information to
   disable path recomputation for specific paths, and the clarification
   of the usage of existing flags within PCEP messages.

   The PCEP extensions described in this document are designed to be
   compatible with any Path Setup Type and are not limited to Circuit
   Style SR policies, ensuring broad applicability across different
   network environments and use cases.

1.1.  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.

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2.  Terminology

   This document uses the following terms defined in [RFC5440]: ERO,
   LSPA, PCC, PCE, PCEP, PCEP Peer, and PCEP speaker.

   This document uses the following term defined in [RFC3031]: LSP.

3.  Overview of Extensions to PCEP

3.1.  New Flags in STATEFUL-PCE-CAPABILITY TLV

   The STATEFUL-PCE-CAPABILITY TLV is an optional TLV introduced in
   [RFC8231] in the OPEN object for stateful PCEP peer capability
   advertisement.  This document defines the following new flags in that
   TLV:

   *  STRICT-PATH-CAPABILITY - 1 bit (Bit Position 18) - If set to 1, it
      indicates support for the Strict-Path flag in LSP-EXTENDED-FLAG
      TLV.  See Section 4.1 for details.

   *  PATH-RECOMPUTATION-CAPABILITY - 1 bit (Bit Position 19) - If set
      to 1, it indicates support for PATH-RECOMPUTATION TLV.  See
      Section 4.2 for details.

3.2.  New Flag in the LSP-EXTENDED-FLAG TLV

   The LSP-EXTENDED-FLAG TLV was introduced in Section 3.1 of [RFC9357].
   This document specifies new Strict-Path flag in the LSP-EXTENDED-FLAG
   TLV.

   O (Strict-Path) - 1 bit (Bit Position 4): If set to 1, this indicates
   to the PCE that a path exclusively made of strict hops is required.
   The strict hop definition is described in Section 4.1

3.3.  PATH-RECOMPUTATION TLV

   This document defines new TLV for the LSPA Object for encoding
   information whether path recomputation is allowed for delegated LSP.
   The TLV is optional.  If the TLV is included in LSPA object, the PCE
   MUST NOT recompute the path in cases specified by flags in the TLV.
   Only the first instance of this TLV MUST be processed, subsequent
   instances MUST be ignored.

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     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 = 72          |             Length = 4         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |             Reserved         |      Flags                 |P|F|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                  Figure 1: PATH-RECOMPUTATION TLV Format

   Type (16 bits): 72.

   Length (16 bits): 4.

   Reserved (16 bits):  This field MUST be set to zero on transmission
      and MUST be ignored on receipt.

   Flags (16 bits):  This document defines the following flag bits.  The
      other bits MUST be set to zero by the sender and MUST be ignored
      by the receiver.

      *  P (Permanent): If set to 1, the PCE MUST NOT recompute path
         even if the current path does not satisfy path computation
         constraints.  If this flag is cleared, then the PCE SHOULD
         recompute the path if the original path is invalidated.

      *  F (Force): If set to 1, the PCE MUST NOT update the path
         (exceptions description in Section 4.2).  If the flag is
         cleared, the PCE MAY update the path based on an explicit
         request from the operator.

4.  Operation

4.1.  Strict Path Enforcement

   PCC MAY set the O flag in LSP-EXTENDED-FLAG TLV in a PCRpt message
   sent to the PCE to indicate that a path exclusively made of strict
   hops is required.  It MUST NOT be set to 1 if one or both PCEP
   speakers have not set the STRICT-PATH-CAPABILITY flag to 1 in the
   STATEFUL-PCE-CAPABILITY TLV.  If the PCEP peer received LSP-EXTENDED-
   FLAG TLV with O flag set, but it does not support that flag, it MUST
   send PCErr with Error-Type = 2 (Capability not supported).

   O flag cleared or LSP-EXTENDED-FLAG TLV not included indicates that a
   loose path is acceptable.

   In PCUpd or PCInitiate messages, PCE MAY set O bit if the strict path
   is provided.

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   The flag is applicable only for stateful messages.  Existing O flag
   in RP object MAY be used to indicate similar behavior in PCReq and
   PCRep messages as described in as described in Section 7.4.1 of
   [RFC5440].

   If the O flag is set to 1 for both stateful and stateless messages
   for SR paths introduced in [RFC8664], the PCE MUST use only Segment
   Identifiers (SIDs) that explicitly specify adjacencies for packet
   forwarding.  For example, Adjacency SIDs MAY be used, but Prefix SIDs
   MUST NOT be used (even if there is only one adjacency).

4.2.  Path Recomputation

   PCC MAY set flags in PATH-RECOMPUTATION TLV to control path
   computation behavior on the PCE side.  If TLV is not included, then
   the PCE MAY use local policy to trigger path computation or LSP path
   update.

   If a PCEP speaker does not recognize the PATH-RECOMPUTATION TLV, it
   MUST ignore the TLV based on Section 7.1 of [RFC5440].  If a PCEP
   speaker recognizes the TLV but does not support the TLV, it MUST send
   PCErr with Error-Type = 2 (Capability not supported).

   The presence of the TLV blocks path recomputation based on various
   triggers like topology update, any periodic update, or changed state
   of other LSPs in the network.  The LSP path MAY be modified if
   forwarded packets will still use the same path.  For example, if the
   same path can be encoded using Adjacency, Binding, Prefix, or other
   SIDs, then PCE MAY switch between various representations of the same
   path.

   If the P flag is cleared, the PCE MAY recompute if the current path
   is not considered valid, for example after a topology update
   resulting in a path not satisfying LSP's path constraints, but it
   MUST NOT recompute path if the current path is not optimal.

   If the P flag is set, the PCE MUST NOT recompute the path during the
   LSP lifetime even if the path is invalidated.  The only exception is
   an explicit request from the operator to recompute the path.

   If the F flag is cleared, the path update triggered manually by an
   operator or any northbound interface of PCE MAY be done.  If the flag
   is set then PCE can update the path only to tear down LSP by sending
   a PCUpd message with empty ERO ERO or to bring it up again with path,
   which was used before LSP was torn down.

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   TLV MAY be included in PCInitiate and PCUpd messages to indicate,
   which triggers will be disabled on the PCE.  PCC MUST reflect flag
   values in PCRpt messages to forward the requirement to other PCEs in
   the network.

5.  Manageability Considerations

   All manageability requirements and considerations listed in
   [RFC5440], [RFC8231] and [RFC8281] apply to PCEP protocol extensions
   defined in this document.  In addition, the requirements and
   considerations listed in this section apply.

5.1.  Control of Function and Policy

   A PCE or PCC implementation MAY allow the capability of supporting
   PCEP extensions introduced in this document to be enabled/disabled as
   part of the global configuration.

5.2.  Information and Data Models

   An implementation SHOULD allow an operator to view the PCEP peer
   capability defined in this document.  Section 4.1 and 4.1.1 of
   [I-D.ietf-pce-pcep-yang] should be extended to include that
   capability for PCEP peer.

   Section 4.2 of [I-D.ietf-pce-pcep-yang] module should be extended to
   add notification for blocked recomputation that satisfies specified
   constraints if recomputation is blocked using the PATH-RECOMPUTATION
   TLV.

5.3.  Liveness Detection and Monitoring

   Circuit-Style Policy draft [I-D.ietf-spring-cs-sr-policy] is already
   describing connectivity verification and path validity considerations
   for Circuit Style Policies.

5.4.  Verify Correct Operations

   A PCE implementation SHOULD notify the operator in case of blocked
   recomputation for an LSP that no longer satisfies specified
   constraints.  It SHOULD also allow the operator to view LSPs on the
   PCE that does not satisfy specified constraints.

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5.5.  Requirements On Other Protocols

   The PCEP extensions defined in this document do not imply any new
   requirements on other protocols.  The overall concept of Circuit
   Style policies requires interaction with other protocols, but those
   requirements are already described in [I-D.ietf-spring-cs-sr-policy].

5.6.  Impact On Network Operations

   The mechanisms defined in [RFC5440], [RFC8231], and [RFC8281] also
   apply to the PCEP extensions defined in this document.

6.  Implementation Status

   [Note to the RFC Editor - remove this section before publication, as
   well as remove the reference to RFC 7942.]

   This section records the status of known implementations of the
   protocol defined by this specification at the time of posting of this
   Internet-Draft, and is based on a proposal described in [RFC7942].
   The description of implementations in this section is intended to
   assist the IETF in its decision processes in progressing drafts to
   RFCs.  Please note that the listing of any individual implementation
   here does not imply endorsement by the IETF.  Furthermore, no effort
   has been spent to verify the information presented here that was
   supplied by IETF contributors.  This is not intended as, and must not
   be construed to be, a catalog of available implementations or their
   features.  Readers are advised to note that other implementations may
   exist.

   According to [RFC7942], "this will allow reviewers and working groups
   to assign due consideration to documents that have the benefit of
   running code, which may serve as evidence of valuable experimentation
   and feedback that have made the implemented protocols more mature.
   It is up to the individual working groups to use this information as
   they see fit".

6.1.  Cisco

   *  Organization: Cisco Systems

   *  Implementation: IOS-XR PCC and PCE.

   *  Description: PCEP extensions supported using VENDOR-INFORMATION
      Object.

   *  Maturity Level: Production.

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   *  Coverage: Partial.

   *  Contact: ssidor@cisco.com

7.  Security Considerations

   The security considerations described in [RFC5440], [RFC8231],
   [RFC8253],[RFC8281] and [RFC8664] in itself.

   Note that this specification introduces the possibility to block path
   recomputation after various topology events.  This creates an
   additional vulnerability if the security mechanisms of [RFC5440],
   [RFC8231], and [RFC8281] are not used.  If there is no integrity
   protection on the session, then an attacker could block path updates
   from PCE potentially resulting in a traffic drop.

   As per [RFC8231] it is RECOMMENDED that these PCEP extensions only be
   activated on authenticated and encrypted sessions across PCEs and
   PCCs using Transport Layer Security (TLS) [RFC8253], as per the
   recommendations and best current practices in RFC 9325 [BCP195]
   (unless explicitly set aside in [RFC8253]).

8.  IANA Considerations

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

8.1.  STATEFUL-PCE-CAPABILITY

   [RFC8231] defines the STATEFUL-PCE-CAPABILITY.  IANA is requested to
   confirm the following allocations within the "STATEFUL-PCE-CAPABILITY
   TLV Flag Field" registry of the "Path Computation Element Protocol
   (PCEP) Numbers" registry group:

          +=====+===============================+===============+
          | Bit | Description                   | Reference     |
          +=====+===============================+===============+
          |  18 | STRICT-PATH-CAPABILITY        | This document |
          +-----+-------------------------------+---------------+
          |  19 | PATH-RECOMPUTATION-CAPABILITY | This document |
          +-----+-------------------------------+---------------+

                                  Table 1

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8.2.  LSP-EXTENDED-FLAG TLV

   [RFC9357] defines the LSP-EXTENDED-FLAG TLV.  IANA is requested to
   confirm the following allocation within the "LSP-EXTENDED-FLAG TLV
   Flag Field" registry of the "Path Computation Element Protocol (PCEP)
   Numbers" registry group:

              +=====+======================+===============+
              | Bit | Description          | Reference     |
              +=====+======================+===============+
              |  4  | Strict-Path Flag (O) | This document |
              +-----+----------------------+---------------+

                                 Table 2

8.3.  PATH-RECOMPUTATION TLV

   IANA is requested to confirm the following allocation within the
   "PCEP TLV Type Indicators" registry of the "Path Computation Element
   Protocol (PCEP) Numbers" registry group:

           +==========+========================+===============+
           | TLV Type | TLV Name               | Reference     |
           +==========+========================+===============+
           |    72    | PATH-RECOMPUTATION TLV | This document |
           +----------+------------------------+---------------+

                                  Table 3

8.4.  PATH-RECOMPUTATION TLV Flag Field

   IANA has created a new registry named "PATH-RECOMPUTATION TLV Flag
   Field" within the "Path Computation Element Protocol (PCEP) Numbers"
   registry group.  New values are to be assigned by "IETF Review"
   [RFC8126].  Each bit should be tracked with the following qualities:

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

   *  Description

   *  Reference

   The registry contains the following codepoints, with initial values,
   to be assigned by IANA with the reference set to this document:

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                  +======+=============+===============+
                  | Bit  | Description | Reference     |
                  +======+=============+===============+
                  | 0-13 | Unassigned  |               |
                  +------+-------------+---------------+
                  |  14  | Permanent   | This document |
                  +------+-------------+---------------+
                  |  15  | Force       | This document |
                  +------+-------------+---------------+

                                 Table 4

9.  References

9.1.  Normative References

   [BCP195]   Best Current Practice 195,
              <https://www.rfc-editor.org/info/bcp195>.
              At the time of writing, this BCP comprises the following:

              Moriarty, K. and S. Farrell, "Deprecating TLS 1.0 and TLS
              1.1", BCP 195, RFC 8996, DOI 10.17487/RFC8996, March 2021,
              <https://www.rfc-editor.org/info/rfc8996>.

              Sheffer, Y., Saint-Andre, P., and T. Fossati,
              "Recommendations for Secure Use of Transport Layer
              Security (TLS) and Datagram Transport Layer Security
              (DTLS)", BCP 195, RFC 9325, DOI 10.17487/RFC9325, November
              2022, <https://www.rfc-editor.org/info/rfc9325>.

   [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>.

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   [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>.

   [RFC8253]  Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody,
              "PCEPS: Usage of TLS to Provide a Secure Transport for the
              Path Computation Element Communication Protocol (PCEP)",
              RFC 8253, DOI 10.17487/RFC8253, October 2017,
              <https://www.rfc-editor.org/info/rfc8253>.

   [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>.

   [RFC8664]  Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
              and J. Hardwick, "Path Computation Element Communication
              Protocol (PCEP) Extensions for Segment Routing", RFC 8664,
              DOI 10.17487/RFC8664, December 2019,
              <https://www.rfc-editor.org/info/rfc8664>.

   [RFC9357]  Xiong, Q., "Label Switched Path (LSP) Object Flag
              Extension for Stateful PCE", RFC 9357,
              DOI 10.17487/RFC9357, February 2023,
              <https://www.rfc-editor.org/info/rfc9357>.

9.2.  Informative References

   [I-D.ietf-pce-pcep-yang]
              Dhody, D., Beeram, V. P., Hardwick, J., and J. Tantsura,
              "A YANG Data Model for Path Computation Element
              Communications Protocol (PCEP)", Work in Progress,
              Internet-Draft, draft-ietf-pce-pcep-yang-30, 26 January
              2025, <https://datatracker.ietf.org/doc/html/draft-ietf-
              pce-pcep-yang-30>.

   [I-D.ietf-spring-cs-sr-policy]
              Schmutzer, C., Ali, Z., Maheshwari, P., Rokui, R., and A.
              Stone, "Circuit Style Segment Routing Policy", Work in
              Progress, Internet-Draft, draft-ietf-spring-cs-sr-policy-
              10, 24 June 2025, <https://datatracker.ietf.org/doc/html/
              draft-ietf-spring-cs-sr-policy-10>.

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   [RFC3031]  Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
              Label Switching Architecture", RFC 3031,
              DOI 10.17487/RFC3031, January 2001,
              <https://www.rfc-editor.org/info/rfc3031>.

   [RFC7942]  Sheffer, Y. and A. Farrel, "Improving Awareness of Running
              Code: The Implementation Status Section", BCP 205,
              RFC 7942, DOI 10.17487/RFC7942, July 2016,
              <https://www.rfc-editor.org/info/rfc7942>.

Contributors

   Daniel Voyer
   Bell Canada
   Email: daniel.voyer@bell.ca

   Reza Rokui
   Ciena
   Email: rrokui@ciena.com

   Tarek Saad
   Cisco Systems, Inc.
   Email: tsaad.net@gmail.com

   Zafar Ali
   Cisco Systems, Inc.
   Email: zali@cisco.com

   Ran Chen
   ZTE Corporation
   Email: chen.ran@zte.com.cn

   Quan Xiong
   ZTE Corporation
   Email: xiong.quan@zte.com.cn

   Dhruv Dhody
   Huawei
   Email: dhruv.ietf@gmail.com

Sidor, et al.           Expires 28 December 2025               [Page 13]
Internet-Draft       PCEP extensions for CS Policies           June 2025

   Christian Schmutzer
   Cisco Systems, Inc.
   Email: cschmutz@cisco.com

Authors' Addresses

   Samuel Sidor
   Cisco Systems, Inc.
   Eurovea Central 3.
   811 09 Bratislava
   Slovakia
   Email: ssidor@cisco.com

   Praveen Maheshwari
   Airtel India
   Email: Praveen.Maheshwari@airtel.com

   Andrew Stone
   Nokia
   Email: andrew.stone@nokia.com

   Luay Jalil
   Verizon
   Email: luay.jalil@verizon.com

   Shuping Peng
   Huawei Technologies
   Email: pengshuping@huawei.com

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