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PCE                                                              H. Chen
Internet-Draft                                             China Telecom
Intended status: Standards Track                                 H. Yuan
Expires: January 9, 2021                                        UnionPay
                                                                 T. Zhou
                                                                   W. Li
                                                             G. Fioccola
                                                                  Huawei
                                                            July 8, 2020


                PCEP SR Policy Extensions to Enable IFIT
                    draft-chen-pce-sr-policy-ifit-01

Abstract

   Segment Routing (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.  In-situ Flow Information Telemetry
   (IFIT) refers to network OAM applications that apply dataplane on-
   path telemetry techniques.  This document defines extensions to PCEP
   to distribute SR policies carrying IFIT information.  So that IFIT
   behavior can be enabled automatically when the SR policy is applied.

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
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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 January 9, 2021.




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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
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   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.  IFIT Attributes in SR Policy  . . . . . . . . . . . . . . . .   3
   3.  SR Policy for IOAM  . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  IOAM Pre-allocated Trace Option TLV . . . . . . . . . . .   4
     3.2.  IOAM Incremental Trace Option TLV . . . . . . . . . . . .   5
     3.3.  IOAM Directly Export Option TLV . . . . . . . . . . . . .   5
     3.4.  IOAM Edge-to-Edge Option TLV  . . . . . . . . . . . . . .   6
   4.  SR Policy for Enhanced Alternate Marking  . . . . . . . . . .   7
   5.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .   8
     5.1.  PCE Initiated SR Policy . . . . . . . . . . . . . . . . .   8
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  10
   Appendix A. . . . . . . . . . . . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   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.

   In-situ Flow Information Telemetry (IFIT) refers to network OAM
   applications that apply dataplane 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.



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   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.  The SR policy native IFIT can
   facilitate the closed loop control, and enable the automation of SR
   service.

   This document defines extensions to PCEP to distribute SR policies
   carrying IFIT information.  So that IFIT behavior can be enabled
   automatically when the SR policy is applied.

   This PCEP extension allows to signal the IFIT capabilities together
   with the SR-policy.  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.

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

2.  IFIT Attributes in SR Policy

   SR Policy Association Group (SRPAG) is defined in
   [I-D.ietf-pce-segment-routing-policy-cp] to extend PCEP to support
   association among candidate paths of a given SR policy.  SR Policy
   Identifiers TLV, SR Policy Name TLV, SR Policy Candidate Path
   Identifiers TLV, and SR Policy Candidate Path Preference TLV are
   introduced to construct the SR policy structure.

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

   Note that the IFIT attributes here described can also be generalized
   and included as TLVs for other Association Groups.  In this regard
   RFC 8697 [RFC8697] defines the generic mechanism to associate sets of
   LSPs and a set of attributes, for example IFIT.

3.  SR Policy for IOAM

   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




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   mechanisms can be leveraged where active OAM do not apply or do not
   offer the desired results.

   When SR policy enables the IOAM, the IOAM header will be inserted
   into every packet of the traffic that is steered into the SR paths.

   This document aims to define the control plane.  While a relevant
   document for the data plane is [I-D.ietf-ippm-ioam-ipv6-options] for
   Segment Routing over IPv6 data plane (SRv6).

3.1.  IOAM Pre-allocated Trace Option 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 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                 |            Length             |
   +---------------------------------------------------------------+
   |       Namespace ID            |            Rsvd1              |
   +-------------------------------+-----------------------+-------+
   |         IOAM Trace Type                      | Flags  | Rsvd2 |
   +----------------------------------------------+--------+-------+

                Fig. 1 IOAM Pre-allocated Trace Option TLV

   Where:

   Type: 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].





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   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.

3.2.  IOAM Incremental Trace Option 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 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                 |            Length             |
   +---------------------------------------------------------------+
   |       Namespace ID            |            Rsvd1              |
   +-------------------------------+-----------------------+-------+
   |         IOAM Trace Type                      | Flags  | Rsvd2 |
   +----------------------------------------------+--------+-------+

                 Fig. 2 IOAM Incremental Trace Option TLV

   Where:

   Type: 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 TLV in section 4.1.

3.3.  IOAM Directly Export Option 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 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                |        Length                 |
   +---------------------------------------------------------------+
   |        Namespace ID           |            Flags              |
   +-------------------------------+---------------+---------------+
   |               IOAM Trace Type                 |      Rsvd     |
   +-----------------------------------------------+---------------+
   |                         Flow ID                               |
   +---------------------------------------------------------------+

                  Fig. 3 IOAM Directly Export Option TLV

   Where:

   Type: 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 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.

3.4.  IOAM Edge-to-Edge Option 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 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                  |          Length               |
   +---------------------------------------------------------------+
   |        Namespace ID           |         IOAM E2E Type         |
   +-------------------------------+-------------------------------+

                    Fig. 4 IOAM Edge-to-Edge Option TLV

   Where:

   Type: 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].

   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.  SR Policy for Enhanced Alternate Marking

   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.

   This document aims to define the control plane.  While 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 EAM 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               |             Length            |
   +-------------------------------+-------+---------------+-------+
   |           FlowMonID                   |     Period    | Rsvd  |
   +---------------------------------------+---------------+-------+

   Where:



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   Type: 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].

   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.

5.  Examples

5.1.  PCE Initiated SR Policy

   The interactions between the PCE and PCC is the same as described in
   [I-D.ietf-pce-segment-routing-policy-cp].  The only change is to take
   the additional optional IFIT TLVs within the SRPAG object.

   PCE sends PCInitiate message, containing the SRPAG Association
   object.  The Association Source is set to the IP address of the PCC
   and the Association ID is set to 0xFFFF.

   PCC uses the color, endpoint, preference and IFIT option 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.  The Originator of the candidate path is set
   to be the address of the PCE that is sending the PCInitiate message.

   PCC sends a PCRpt message back to the PCE to report the newly created
   Candidate Path.  The PCRpt message contains the SRPAG Association
   object.  The Association Source is set to the IP address of the PCC
   and the Association ID is set to a number that PCC locally chose to
   represent the SR Policy.

6.  IANA Considerations

   This document defines new IFIT TLVs for carrying additional
   information about SR policy and SR candidate paths.  IANA is
   requested to make the assignment of a new value for the existing
   "PCEP TLV Type Indicators" registry as follows:







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   Codepoint    Description                      Reference
   -------------------------------------------------------------
   TBD1         IOAM Pre-allocated Trace         This document
                Option TLV
   TBD2         IOAM Incremental Trace           This document
                Option TLV
   TBD3         IOAM Directly Export             This document
                Option TLV
   TBD4         IOAM Edge-to-Edge                This document
                Option TLV
   TBD5         Enhanced Alternate Marking       This document
                TLV

7.  Security Considerations

   TBD.

8.  Acknowledgements

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>.

   [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>.

   [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>.

   [RFC8697]  Minei, I., Crabbe, E., Sivabalan, S., Ananthakrishnan, H.,
              Dhody, D., and Y. Tanaka, "Path Computation Element
              Communication Protocol (PCEP) Extensions for Establishing
              Relationships between Sets of Label Switched Paths
              (LSPs)", RFC 8697, DOI 10.17487/RFC8697, January 2020,
              <https://www.rfc-editor.org/info/rfc8697>.







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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., Pignataro, C., Gredler, H.,
              Leddy, J., Youell, S., Mizrahi, T., Mozes, D., Lapukhov,
              P., remy@barefootnetworks.com, r., daniel.bernier@bell.ca,
              d., and J. Lemon, "Data Fields for In-situ OAM", draft-
              ietf-ippm-ioam-data-09 (work in progress), March 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-00 (work in progress), February 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-01
              (work in progress), January 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-01 (work in progress), March 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., Sivabalan, S., Voyer, D., Bogdanov, A., and
              P. Mattes, "Segment Routing Policy Architecture", draft-
              ietf-spring-segment-routing-policy-07 (work in progress),
              May 2020.






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   [I-D.qin-idr-sr-policy-ifit]
              Qin, F., Yuan, H., Zhou, T., Min, L., and G. Fioccola,
              "BGP SR Policy Extensions to Enable IFIT", draft-qin-idr-
              sr-policy-ifit-00 (work in progress), January 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


   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









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   Giuseppe Fioccola
   Huawei
   Riesstrasse, 25
   Munich
   Germany

   Email: giuseppe.fioccola@huawei.com












































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