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Versions: (draft-chen-pce-sr-policy-ifit) 00 01

PCE                                                              H. Chen
Internet-Draft                                             China Telecom
Intended status: Standards Track                                 H. Yuan
Expires: March 1, 2021                                          UnionPay
                                                                 T. Zhou
                                                                   W. Li
                                                             G. Fioccola
                                                                 Y. Wang
                                                                  Huawei
                                                         August 28, 2020


  Path Computation Element Communication Protocol (PCEP) Extensions to
                              Enable IFIT
                      draft-chen-pce-pcep-ifit-00

Abstract

   This document defines PCEP extensions to distribute In-situ Flow
   Information Telemetry (IFIT) information.  So that IFIT behavior can
   be enabled automatically when the path is instantiated.  In-situ Flow
   Information Telemetry (IFIT) refers to network OAM data plane on-path
   telemetry techniques, in particular the most popular are In-situ OAM
   (IOAM) and Alternate Marking.  The IFIT attributes here described can
   be generalized for all path types but the application to Segment
   Routing (SR) is considered in this document.  The SR policy is a set
   of candidate SR paths consisting of one or more segment lists and
   necessary path attributes.  It enables instantiation of an ordered
   list of segments with a specific intent for traffic steering.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

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



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   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 March 1, 2021.

Copyright Notice

   Copyright (c) 2020 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 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  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  PCEP Extensions for IFIT Attributes . . . . . . . . . . . . .   4
     2.1.  IFIT for SR Policies  . . . . . . . . . . . . . . . . . .   4
   3.  IFIT capability advertisement TLV . . . . . . . . . . . . . .   4
   4.  IFIT Attributes TLV . . . . . . . . . . . . . . . . . . . . .   5
     4.1.  IOAM Sub-TLVs . . . . . . . . . . . . . . . . . . . . . .   7
       4.1.1.  IOAM Pre-allocated Trace Option Sub-TLV . . . . . . .   7
       4.1.2.  IOAM Incremental Trace Option Sub-TLV . . . . . . . .   8
       4.1.3.  IOAM Directly Export Option Sub-TLV . . . . . . . . .   9
       4.1.4.  IOAM Edge-to-Edge Option Sub-TLV  . . . . . . . . . .  10
     4.2.  Enhanced Alternate Marking Sub-TLV  . . . . . . . . . . .  11
   5.  Example of operation  . . . . . . . . . . . . . . . . . . . .  12
     5.1.  PCE Initiated SR Policy with single or multiple
           candidate-paths . . . . . . . . . . . . . . . . . . . . .  12
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  14
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  14
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  14
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  15
   Appendix A. . . . . . . . . . . . . . . . . . . . . . . . . . . .  16
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16







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1.  Introduction

   In-situ Flow Information Telemetry (IFIT) refers to network OAM data
   plane on-path telemetry techniques, including In-situ OAM (IOAM)
   [I-D.ietf-ippm-ioam-data] and Alternate Marking [RFC8321].  It can
   provide flow information on the entire forwarding path on a per-
   packet basis in real time.

   An automatic network requires the Service Level Agreement (SLA)
   monitoring on the deployed service.  So that the system can quickly
   detect the SLA violation or the performance degradation, hence to
   change the service deployment.

   This document defines extensions to PCEP to distribute paths carrying
   IFIT information.  So that IFIT behavior can be enabled automatically
   when the path is instantiated.

   RFC 5440 [RFC5440] describes the Path Computation Element Protocol
   (PCEP) as a communication mechanism between a Path Computation Client
   (PCC) and a Path Computation Element (PCE), or between a PCE and a
   PCE.

   RFC 8231 [RFC8231] specifies extensions to PCEP to enable stateful
   control and it describes two modes of operation: passive stateful PCE
   and active stateful PCE.  Further, RFC 8281 [RFC8281] describes the
   setup, maintenance, and teardown of PCE-initiated LSPs for the
   stateful PCE model, while RFC 8733 [RFC8733] is focused on the active
   stateful PCE, where the LSPs are controlled by the PCE.

   When a PCE is used to initiate paths using PCEP, it is important that
   the head end of the path also understands the IFIT behavior that is
   intended for the path.  When PCEP is in use for path initiation it
   makes sense for that same protocol to be used to also carry the IFIT
   attributes that describe the IOAM or Alternate Marking procedure that
   needs to be applied to the data that flow those paths.

   The PCEP extension defined in this document allows to signal the IFIT
   capabilities.  In this way IFIT methods are automatically activated
   and running.  The flexibility and dynamicity of the IFIT applications
   are given by the use of additional functions on the controller and on
   the network nodes, but this is out of scope here.

   The Use Case of Segment Routing (SR) is discussed considering that
   IFIT methods are becoming mature for Segment Routing over the MPLS
   data plane (SR-MPLS) and Segment Routing over IPv6 data plane (SRv6).
   In this way SR policy native IFIT can facilitate the closed loop
   control and enable the automation of SR service.




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   Segment Routing (SR) policy [I-D.ietf-spring-segment-routing-policy]
   is a set of candidate SR paths consisting of one or more segment
   lists and necessary path attributes.  It enables instantiation of an
   ordered list of segments with a specific intent for traffic steering.

   It is to be noted the companion document [I-D.qin-idr-sr-policy-ifit]
   that proposes the BGP extension to enable IFIT methods for SR policy.

2.  PCEP Extensions for IFIT Attributes

   This document is to add IFIT attribute TLVs as PCEP Extensions.  The
   following sections will describe the requirement and usage of
   different IFIT modes, and define the corresponding TLV encoding in
   PCEP.

   The IFIT attributes here described can be generalized and included as
   TLVs carried inside the LSPA (LSP Attributes) object in order to be
   applied for all path types, as long as they support the relevant data
   plane telemetry method.  IFIT TLVs are o ptional and can be taken
   into account by the PCE during path computation.  In general, the
   LSPA object is carried within a PCInitiate message or a PCRpt
   message.

   In this document it is considered the case of SR Policy since IOAM
   and Alternate Marking are more mature especially for Segment Routing
   (SR) and for IPv6.

2.1.  IFIT for SR Policies

   RFC 8664 [RFC8664] and [I-D.ietf-pce-segment-routing-ipv6] specify
   extensions to the Path Computation Element Communication Protocol
   (PCEP) that allow a stateful PCE to compute and initiate Traffic-
   Engineering (TE) paths, as well as a Path Computation Client (PCC) to
   request a path subject to certain constraints and optimization
   criteria in SR networks both for SR-MPLS and SRv6.

   IFIT attibutes, here defined as TLVs for the LSPA object, complement
   both RFC 8664 [RFC8664], [I-D.ietf-pce-segment-routing-ipv6] and
   [I-D.ietf-pce-segment-routing-policy-cp].

3.  IFIT capability advertisement TLV

   During the PCEP initialization phase, PCEP speakers (PCE or PCC)
   SHOULD advertise their support of IFIT methods (e.g.  IOAM and
   Alternate Marking).

   A PCEP speaker includes the IFIT TLVs in the OPEN object to advertise
   its support for PCEP IFIT extensions.



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   RFC 8664 [RFC8664] and and [I-D.ietf-pce-segment-routing-ipv6] define
   a new Path Setup Type (PST) for SR and also define the SR-PCE-
   CAPABILITY sub-TLV.  This document defined a new IFIT-CAPABILITY TLV,
   that is an optional TLV for use in the OPEN Object for IFIT
   attributes via PCEP capability advertisement.

   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                |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                             Flag                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Fig. 1 IFIT-CAPABILITY TLV Format

   Where:

   Type: to be assigned by IANA.

   Length: The Length field defines the length of the value portion in
   bytes as per RFC 5440 [RFC5440].

   Flag: No flags are defined for this TLV in this document.  Unassigned
   bits are considered reserved.  They MUST be set to 0 on transmission
   and MUST be ignored on receipt.

   Advertisement of the IFIT-CAPABILITY TLV implies support of IFIT
   methods (IOAM and/or Alternate Marking) as well as the objects, TLVs,
   and procedures defined in this document.  It is worth mentioning that
   IOAM and Alternate Marking can be activated one at a time or can
   coexist; so it is possible to have only IOAM or only Alternate
   Marking enabled but they are recognized in general as IFIT
   capability.

4.  IFIT Attributes TLV

   The IFIT TLV provides the configurable knobs of the IFIT feature, and
   it can be included as an optional TLV in the LSPA object (as
   described in RFC 5440 [RFC5440]).

   For a PCE-initiated LSP RFC 8281 [RFC8281], this TLV is included in
   the LSPA object with the PCInitiate message.  For the PCC-initiated
   delegated LSPs, this TLV is carried in the Path Computation State
   Report (PCRpt) message in the LSPA object.  This TLV is also carried
   in the LSPA object with the Path Computation Update Request (PCUpd)
   message to direct the PCC (LSP head-end) to make updates to IFIT
   attributes.



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   The TLV is encoded in all PCEP messages for the LSP if IFIT feature
   is enabled.  The absence of the TLV indicates the PCEP speaker wishes
   to disable the feature.  This TLV includes multiple IFIT-ATTRIBUTES
   sub-TLVs.  The IFIT-ATTRIBUTES sub-TLVs are included if there is a
   change since the last information sent in the PCEP message.  The
   default values for missing sub-TLVs apply for the first PCEP message
   for the LSP.

   The format of the IFIT-ATTRIBUTES TLV is shown in the following
   figure:

   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              |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   //                            sub-TLVs                          //
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Fig. 2 IFIT-ATTRIBUTES TLV Format

   Where:

   Type: to be assigned by IANA.

   Length: The Length field defines the length of the value portion in
   bytes as per RFC 5440 [RFC5440].

   Value: This comprises one or more sub-TLVs.

   The following sub-TLVs are defined in this document:


















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   +------+-----+--------------------------------------+
   | Type | Len | Name                                 |
   +======+=====+======================================+
   | 1    |  8  | IOAM Pre-allocated Trace Option      |
   +------+-----+--------------------------------------+
   | 2    |  8  | IOAM Incremental Trace Option        |
   +------+-----+--------------------------------------+
   | 3    | 12  | IOAM Directly Export Option          |
   +------+-----+--------------------------------------+
   | 4    |  4  | IOAM Edge-to-Edge Option             |
   +------+-----+--------------------------------------+
   | 5    |  4  | Enhanced Alternate Marking           |
   +------+-----+--------------------------------------+

              Fig. 3 Sub-TLV Types of the IFIT-ATTRIBUTES TLV

4.1.  IOAM Sub-TLVs

   In-situ Operations, Administration, and Maintenance (IOAM)
   [I-D.ietf-ippm-ioam-data] records operational and telemetry
   information in the packet while the packet traverses a path between
   two points in the network.  In terms of the classification given in
   RFC 7799 [RFC7799] IOAM could be categorized as Hybrid Type 1.  IOAM
   mechanisms can be leveraged where active OAM do not apply or do not
   offer the desired results.

   For the SR use case, when SR policy enables IOAM, the IOAM header
   will be inserted into every packet of the traffic that is steered
   into the SR paths.  Since this document aims to define the control
   plane, it is to be noted that a relevant document for the data plane
   is [I-D.ietf-ippm-ioam-ipv6-options] for Segment Routing over IPv6
   data plane (SRv6).

4.1.1.  IOAM Pre-allocated Trace Option Sub-TLV

   The IOAM tracing data is expected to be collected at every node that
   a packet traverses to ensure visibility into the entire path a packet
   takes within an IOAM domain.  The preallocated tracing option will
   create pre-allocated space for each node to populate its information.

   The format of IOAM pre-allocated trace option Sub-TLV is defined as
   follows:









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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=1               |            Length             |
   +---------------------------------------------------------------+
   |       Namespace ID            |            Rsvd1              |
   +-------------------------------+-----------------------+-------+
   |         IOAM Trace Type                      | Flags  | Rsvd2 |
   +----------------------------------------------+--------+-------+

              Fig. 4 IOAM Pre-allocated Trace Option Sub-TLV

   Where:

   Type: 1 (to be assigned by IANA).

   Length: the total length of the value field not including Type and
   Length fields.

   Namespace ID: A 16-bit identifier of an IOAM-Namespace.  The
   definition is the same as described in section 4.4 of
   [I-D.ietf-ippm-ioam-data].

   IOAM Trace Type: A 24-bit identifier which specifies which data types
   are used in the node data list.  The definition is the same as
   described in section 4.4 of [I-D.ietf-ippm-ioam-data].

   Flags: A 4-bit field.  The definition is the same as described in
   [I-D.ietf-ippm-ioam-flags] and section 4.4 of
   [I-D.ietf-ippm-ioam-data].

   Rsvd1: A 16-bit field reserved for further usage.  It MUST be zero.

   Rsvd2: A 4-bit field reserved for further usage.  It MUST be zero.

4.1.2.  IOAM Incremental Trace Option Sub-TLV

   The incremental tracing option contains a variable node data fields
   where each node allocates and pushes its node data immediately
   following the option header.

   The format of IOAM incremental trace option Sub-TLV is defined as
   follows:








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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=2               |            Length             |
   +---------------------------------------------------------------+
   |       Namespace ID            |            Rsvd1              |
   +-------------------------------+-----------------------+-------+
   |         IOAM Trace Type                      | Flags  | Rsvd2 |
   +----------------------------------------------+--------+-------+

               Fig. 5 IOAM Incremental Trace Option Sub-TLV

   Where:

   Type: 2 (to be assigned by IANA).

   Length: the total length of the value field not including Type and
   Length fields.

   All the other fields definition is the same as the pre-allocated
   trace option Sub-TLV in the previous section.

4.1.3.  IOAM Directly Export Option Sub-TLV

   IOAM directly export option is used as a trigger for IOAM data to be
   directly exported to a collector without being pushed into in-flight
   data packets.

   The format of IOAM directly export option Sub-TLV is defined as
   follows:

    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=3              |        Length                 |
   +---------------------------------------------------------------+
   |        Namespace ID           |            Flags              |
   +-------------------------------+---------------+---------------+
   |               IOAM Trace Type                 |      Rsvd     |
   +-----------------------------------------------+---------------+
   |                         Flow ID                               |
   +---------------------------------------------------------------+

                Fig. 6 IOAM Directly Export Option Sub-TLV

   Where:

   Type: 3 (to be assigned by IANA).



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   Length: the total length of the value field not including Type and
   Length fields.

   Namespace ID: A 16-bit identifier of an IOAM-Namespace.  The
   definition is the same as described in section 4.4 of
   [I-D.ietf-ippm-ioam-data].

   IOAM Trace Type: A 24-bit identifier which specifies which data types
   are used in the node data list.  The definition is the same as
   described in section 4.4 of [I-D.ietf-ippm-ioam-data].

   Flags: A 16-bit field.  The definition is the same as described in
   section 3.2 of [I-D.ietf-ippm-ioam-direct-export].

   Flow ID: A 32-bit flow identifier.  The definition is the same as
   described in section 3.2 of [I-D.ietf-ippm-ioam-direct-export].

   Rsvd: A 4-bit field reserved for further usage.  It MUST be zero.

4.1.4.  IOAM Edge-to-Edge Option Sub-TLV

   The IOAM edge to edge option is to carry data that is added by the
   IOAM encapsulating node and interpreted by IOAM decapsulating node.

   The format of IOAM edge-to-edge option Sub-TLV is defined as follows:

    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=4                |          Length               |
   +---------------------------------------------------------------+
   |        Namespace ID           |         IOAM E2E Type         |
   +-------------------------------+-------------------------------+

                  Fig. 7 IOAM Edge-to-Edge Option Sub-TLV

   Where:

   Type: 4 (to be assigned by IANA).

   Length: the total length of the value field not including Type and
   Length fields.

   Namespace ID: A 16-bit identifier of an IOAM-Namespace.  The
   definition is the same as described in section 4.6 of
   [I-D.ietf-ippm-ioam-data].





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   IOAM E2E Type: A 16-bit identifier which specifies which data types
   are used in the E2E option data.  The definition is the same as
   described in section 4.6 of [I-D.ietf-ippm-ioam-data].

4.2.  Enhanced Alternate Marking Sub-TLV

   The Alternate Marking [RFC8321]technique is an hybrid performance
   measurement method, per RFC 7799 [RFC7799] classification of
   measurement methods.  Because this method is based on marking
   consecutive batches of packets.  It can be used to measure packet
   loss, latency, and jitter on live traffic.

   For the SR use case, since this document aims to define the control
   plane, it is to be noted that a relevant document for the data plane
   is [I-D.ietf-6man-ipv6-alt-mark] for Segment Routing over IPv6 data
   plane (SRv6).

   The format of Enhanced Alternate Marking (EAM) Sub-TLV is defined as
   follows:

    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=5             |             Length            |
   +-------------------------------+-------+---------------+-------+
   |           FlowMonID                   |     Period    | Rsvd  |
   +---------------------------------------+---------------+-------+

                 Fig. 8 Enhanced Alternate Marking Sub-TLV

   Where:

   Type: 5 (to be assigned by IANA).

   Length: the total length of the value field not including Type and
   Length fields.

   FlowMonID: A 20-bit identifier to uniquely identify a monitored flow
   within the measurement domain.  The definition is the same as
   described in section 5.3 of [I-D.ietf-6man-ipv6-alt-mark].  It is to
   be noted that PCE also needs to maintain the uniqueness of FlowMonID
   as described in [I-D.ietf-6man-ipv6-alt-mark].

   Period: Time interval between two alternate marking period.  The unit
   is second.

   Rsvd: A 4-bit field reserved for further usage.  It MUST be zero.




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5.  Example of operation

5.1.  PCE Initiated SR Policy with single or multiple candidate-paths

   A PCC or PCE sets the IFIT-CAPABILITY TLV in the Open message during
   the PCEP initialization phase to indicate that it supports the IFIT
   procedures.

   1.  For single candidate-path, PCE sends PCInitiate message,
   containing the SRPAG Association object
   ([I-D.ietf-pce-segment-routing-policy-cp]) and IFIT-ATTRIBUTES via
   LSPA TLVs.  For multiple candidate-paths, PCE sends a separate
   PCInitiate message for every candidate path that it wants to create,
   or it sends multiple LSP objects within a single PCInitiate message.
   The SRPAG Association object
   ([I-D.ietf-pce-segment-routing-policy-cp]) is sent for every LSP in
   the PCInitiate message and the IFIT-ATTRIBUTES are sent as LSPA TLVs.

   2.  For single candidate-path, PCC uses the color, endpoint and
   preference from the SRPAG object to create a new candidate path.  If
   no SR policy exists to hold the candidate path, then a new SR policy
   is created to hold the new candidate-path considering the IFIT LSPA
   TLVs too.  For multiple candidate-paths, PCC creates multiple
   candidate paths under the same SR policy, identified by Color and
   Endpoint and also IFIT-ATTRIBUTES.

   3.  For both single candidate-path and multiple candidate-paths, PCC
   sends a PCRpt message back to the PCE to report the newly created
   Candidate Path.  The PCRpt message contains the SRPAG Association
   object and IFIT-ATTRIBUTES information.

   +-+-+                            +-+-+
   |PCC|                            |PCE|
   +-+-+                            +-+-+
     |                                |
     |<--PCInitiate-------------------|
     |                                |
     |---PCRpt----------------------->|
     |                                |


   The procedure of enabling/disabling IFIT is simple, indeed the PCE
   can update the IFIT-ATTRIBUTES of the LSP by sending subsequent Path
   Computation Update Request (PCUpd) messages.







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   +-+-+                            +-+-+
   |PCC|                            |PCE|
   +-+-+                            +-+-+
     |                                |
     |<--PCUpd------------------------|
     |                                |
     |---PCRpt----------------------->|
     |                                |



6.  IANA Considerations

   This document defines the new IFIT-CAPABILITY TLV and IFIT-ATTRIBUTES
   TLV.  IANA is requested to make the assignment from the "PCEP TLV
   Type Indicators" subregistry of the "Path Computation Element
   Protocol (PCEP) Numbers" registry as follows:

   Value        Description                      Reference
   -------------------------------------------------------------
   TBD1         IFIT-CAPABILITY                  This document

   TBD2         IFIT-ATTRIBUTES                  This document

   This document also specifies the IFIT-ATTRIBUTES sub-TLVs.  IANA is
   requested to create an "IFIT-ATTRIBUTES Sub-TLV Types" subregistry
   within the "Path Computation Element Protocol (PCEP) Numbers"
   registry.

   This document defines the following types:

   Type      Description                         Reference
   -------------------------------------------------------------
   0         Reserved                            This document

   1         IOAM Pre-allocated Trace Option     This document

   2         IOAM Incremental Trace Option       This document

   3         IOAM Directly Export Option         This document

   4         IOAM Edge-to-Edge Option            This document

   5         Enhanced Alternate Marking          This document

   6-65535   Unassigned/Experimental Use         This document





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7.  Security Considerations

   This document defines the new IFIT-CAPABILITY TLV and IFIT Attributes
   TLVs, which do not add any substantial new security concerns beyond
   those already discussed in RFC 8231 [RFC8231] and RFC 8281 [RFC8281]
   for stateful PCE operations.

8.  Acknowledgements

   The authors would like to thank Dhruv Doody for the precious inputs
   and suggestions.

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>.

   [RFC7799]  Morton, A., "Active and Passive Metrics and Methods (with
              Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799,
              May 2016, <https://www.rfc-editor.org/info/rfc7799>.

   [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>.

   [RFC8321]  Fioccola, G., Ed., Capello, A., Cociglio, M., Castaldelli,
              L., Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi,
              "Alternate-Marking Method for Passive and Hybrid
              Performance Monitoring", RFC 8321, DOI 10.17487/RFC8321,
              January 2018, <https://www.rfc-editor.org/info/rfc8321>.




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   [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>.

   [RFC8733]  Dhody, D., Ed., Gandhi, R., Ed., Palle, U., Singh, R., and
              L. Fang, "Path Computation Element Communication Protocol
              (PCEP) Extensions for MPLS-TE Label Switched Path (LSP)
              Auto-Bandwidth Adjustment with Stateful PCE", RFC 8733,
              DOI 10.17487/RFC8733, February 2020,
              <https://www.rfc-editor.org/info/rfc8733>.

9.2.  Informative References

   [I-D.ietf-6man-ipv6-alt-mark]
              Fioccola, G., Zhou, T., Cociglio, M., Qin, F., and R.
              Pang, "IPv6 Application of the Alternate Marking Method",
              draft-ietf-6man-ipv6-alt-mark-01 (work in progress), June
              2020.

   [I-D.ietf-ippm-ioam-data]
              Brockners, F., Bhandari, S., and T. Mizrahi, "Data Fields
              for In-situ OAM", draft-ietf-ippm-ioam-data-10 (work in
              progress), July 2020.

   [I-D.ietf-ippm-ioam-direct-export]
              Song, H., Gafni, B., Zhou, T., Li, Z., Brockners, F.,
              Bhandari, S., Sivakolundu, R., and T. Mizrahi, "In-situ
              OAM Direct Exporting", draft-ietf-ippm-ioam-direct-
              export-01 (work in progress), August 2020.

   [I-D.ietf-ippm-ioam-flags]
              Mizrahi, T., Brockners, F., Bhandari, S., Sivakolundu, R.,
              Pignataro, C., Kfir, A., Gafni, B., Spiegel, M., and J.
              Lemon, "In-situ OAM Flags", draft-ietf-ippm-ioam-flags-02
              (work in progress), July 2020.

   [I-D.ietf-ippm-ioam-ipv6-options]
              Bhandari, S., Brockners, F., Pignataro, C., Gredler, H.,
              Leddy, J., Youell, S., Mizrahi, T., Kfir, A., Gafni, B.,
              Lapukhov, P., Spiegel, M., Krishnan, S., and R. Asati,
              "In-situ OAM IPv6 Options", draft-ietf-ippm-ioam-
              ipv6-options-02 (work in progress), July 2020.







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   [I-D.ietf-pce-segment-routing-ipv6]
              Li, C., Negi, M., Koldychev, M., Kaladharan, P., and Y.
              Zhu, "PCEP Extensions for Segment Routing leveraging the
              IPv6 data plane", draft-ietf-pce-segment-routing-ipv6-06
              (work in progress), July 2020.

   [I-D.ietf-pce-segment-routing-policy-cp]
              Koldychev, M., Sivabalan, S., Barth, C., Peng, S., and H.
              Bidgoli, "PCEP extension to support Segment Routing Policy
              Candidate Paths", draft-ietf-pce-segment-routing-policy-
              cp-00 (work in progress), June 2020.

   [I-D.ietf-spring-segment-routing-policy]
              Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and
              P. Mattes, "Segment Routing Policy Architecture", draft-
              ietf-spring-segment-routing-policy-08 (work in progress),
              July 2020.

   [I-D.qin-idr-sr-policy-ifit]
              Qin, F., Yuan, H., Zhou, T., Fioccola, G., and Y. Wang,
              "BGP SR Policy Extensions to Enable IFIT", draft-qin-idr-
              sr-policy-ifit-02 (work in progress), July 2020.

Appendix A.

Authors' Addresses

   Huanan Chen
   China Telecom
   Guangzhou
   China

   Email: chenhuan6@chinatelecom.cn


   Hang Yuan
   UnionPay
   1899 Gu-Tang Rd., Pudong
   Shanghai
   China

   Email: yuanhang@unionpay.com









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   Tianran Zhou
   Huawei
   156 Beiqing Rd., Haidian District
   Beijing
   China

   Email: zhoutianran@huawei.com


   Weidong Li
   Huawei
   156 Beiqing Rd., Haidian District
   Beijing
   China

   Email: poly.li@huawei.com


   Giuseppe Fioccola
   Huawei
   Riesstrasse, 25
   Munich
   Germany

   Email: giuseppe.fioccola@huawei.com


   Yali Wang
   Huawei
   156 Beiqing Rd., Haidian District
   Beijing
   China

   Email: wangyali11@huawei.com

















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