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Versions: 00 01 02 03

PCE Working Group                                               U. Palle
Internet-Draft                                                  D. Dhody
Intended status: Standards Track                          S. Karunanithi
Expires: September 5, 2018                           Huawei Technologies
                                                           March 4, 2018


       LABEL-DB Synchronization Procedures for a PCE as a central
                           controller(PCECC)
               draft-palle-pce-controller-labeldb-sync-03

Abstract

   PCE as a central controller specifies the procedures and PCEP
   protocol extensions where LSPs are calculated/setup/initiated and
   label forwarding entries are downloaded through a centralized PCE
   server to each network devices along the LSP path while leveraging
   the existing PCE technologies as much as possible.

   Labels downloaded to forwarding entries requires a reliable
   synchronization mechanism between the path computation clients (PCCs)
   and the PCE.  The basic mechanism for label database (LABEL-DB
   synchronization is part of the PCE as a central controller
   specification.  This document presents motivations for optimizations
   to the LABEL-DB synchronization and the corresponding PCEP procedures
   and extensions.

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
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   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 September 5, 2018.








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Copyright Notice

   Copyright (c) 2018 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
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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  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  LABEL-DB Synchronization  . . . . . . . . . . . . . . . . . .   3
   3.  Optimizations for LABEL-DB Synchronization  . . . . . . . . .   4
     3.1.  LABEL-DB Synchronization Avoidance Procedure  . . . . . .   4
     3.2.  Incremental LABEL-DB Synchronization Procedure  . . . . .   8
   4.  PCEP Extensions . . . . . . . . . . . . . . . . . . . . . . .  10
     4.1.  Extension of SRP object . . . . . . . . . . . . . . . . .  10
     4.2.  Extension of PCECC Capability sub-TLV . . . . . . . . . .  10
     4.3.  New LABEL-DB-VERSION TLV  . . . . . . . . . . . . . . . .  11
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
     5.1.  PCEP TLV Type Indicators  . . . . . . . . . . . . . . . .  12
     5.2.  PCECC-CAPABILITY sub-TLV  . . . . . . . . . . . . . . . .  12
   6.  Manageability Considerations  . . . . . . . . . . . . . . . .  12
     6.1.  Control of Function and Policy  . . . . . . . . . . . . .  12
     6.2.  Information and Data Models . . . . . . . . . . . . . . .  12
     6.3.  Liveness Detection and Monitoring . . . . . . . . . . . .  12
     6.4.  Verify Correct Operations . . . . . . . . . . . . . . . .  12
     6.5.  Requirements On Other Protocols . . . . . . . . . . . . .  13
     6.6.  Impact On Network Operations  . . . . . . . . . . . . . .  13
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  13
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  13
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14








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1.  Introduction

   [I-D.zhao-pce-pcep-extension-for-pce-controller] specify the
   procedures and PCEP protocol extensions for using the PCE as the
   central controller [RFC8283] and user cases where LSPs are
   calculated/setup/initiated/downloaded through extending the existing
   PCE architectures and PCEP.

   [I-D.zhao-pce-pcep-extension-for-pce-controller] and
   [I-D.zhao-pce-pcep-extension-pce-controller-sr] specifies reliable
   synchronization mechanism between the path computation clients (PCCs)
   and the PCECC.

   This draft specify the optimizations for LABEL-DB synchronization and
   the corresponding PCEP procedures and extensions.

   [Important Note - [I-D.zhao-pce-pcep-extension-for-pce-controller]
   defined new messages for label download and cleanup.  The authors and
   WG also debated on the use of existing PCEP messages.  The appendix
   of the document includes the details related to use of existing
   messages.  This document is related to new messages as a new
   procedure for Label DB sync was defined.  In case existing messages
   are used, some modifications needs to be made to the existing LSP-DB
   synchronization mechanism to also handle the label synchronization.
   These details are not present in the document at this stage.  ]

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.

2.  LABEL-DB Synchronization

   PCECC MUST maintains the LABEL-DB for each PCEP session separately.
   The purpose of LABEL-DB synchronization is to make sure that the
   PCECC's view of LABEL-DB matches with the PCC's LABEL-DB.  The LABEL-
   DB synchronization MUST be performed from PCECC to PCC immediately
   after the LSP state synchronization.  [RFC8231] describes the basic
   mechanism for LSP state synchronization.  [RFC8233] describes the
   optimizations for LSP state synchronization.

   Full LABEL-DB synchronization performed from PCECC to PCC on Initial
   session UP or every session flap is described in
   [I-D.zhao-pce-pcep-extension-for-pce-controller] and
   [I-D.zhao-pce-pcep-extension-pce-controller-sr].



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   Providing an Optimizations for LABEL-DB synchronization can result in
   significant savings in both control-plane data exchanges and the time
   it takes for the PCC to become fully operational.

   Optimizations for LABEL-DB synchronization describes the need that
   both PCEP speakers support label database version capability and
   maintain label database version for each session.  See Section 3 for
   detail procedures.

   [Editor's Note: [I-D.zhao-pce-pcep-extension-for-pce-controller]
   defines new messages PCLabelUpd and PCLabelRpt.  Questions where
   raised on the need for the new messages.  Further appendix in
   [I-D.zhao-pce-pcep-extension-for-pce-controller] and
   [I-D.zhao-pce-pcep-extension-pce-controller-sr] describes how the
   existing messages can be extended to add this functionality.  WG
   needs to decide the final direction i.e. new specific messages are
   needed or existing PCEP messages can be extended.  The optimization
   procedure would need to be modified based on the above decision.]

3.  Optimizations for LABEL-DB Synchronization

   This section add some of the optimization mechanisms for LABEL-DB
   synchronization.  By default, the full LABEL-DB synchronization is
   performed.

3.1.  LABEL-DB Synchronization Avoidance Procedure

   The LABEL-DB synchronization MAY be skipped following a PCEP session
   restart if there is no change in the LABEL-DB of the session at
   PCECC, during the period prior to session re-initialization.  To be
   able to make this determination, labels must be exchanged and
   maintained by both PCECC and PCC during normal operation.  This is
   accomplished by keeping track of the changes to the label database,
   using a version tracking field called the Label Database Version
   Number.

   The Label Database Version Number, carried in LABEL-DB-VERSION TLV
   (see Section 4.3), is owned by a PCECC and it MUST be incremented by
   1 for each successive change in the PCECC's label database.  The
   Label Database Version Number MUST start at 1 and may wrap around.
   Values 0 and 0xFFFFFFFFFFFFFFFF are reserved.  If either of the two
   values are used during LABEL-DB synchronization, the PCC speaker
   receiving this node should send back a PCErr with Error-type TBD1
   Error-value 3 'Received an invalid Label Database Version Number',
   and close the PCEP session.  Operations that trigger a change to the
   Label database include an addition or deletion of labels that would
   trigger a label update to the PCC.




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   LABEL-DB synchronization avoidance is advertised on a PCEP session
   during session startup using the INCLUDE-LABEL-DB-VERSION (I) bit in
   the PCECC capability sub-TLV (see Section 4.2).  The PCEP peer MAY
   include the SPEAKER-ENTITY-ID TLV described in [RFC8233] in the OPEN
   message to identify the peer in case of IP address change.

   If both PCEP speakers set the I flag in the OPEN object's PCECC
   Capability sub-TLV to 1, the PCECC MUST include the LABEL-DB-VERSION
   TLV in each LABEL object of the PCLabelUpd message.  If the LABEL-DB-
   VERSION TLV is missing in a PCLabelUpd message, the PCC will generate
   an error with Error-Type 6 (mandatory object missing) and Error-Value
   TBD2 'LABEL-DB-VERSION TLV missing' and close the session.  If LABEL-
   DB synchronization avoidance has not been enabled on a PCEP session,
   the PCECC SHOULD NOT include the LABEL-DB-VERSION TLV in the LABEL
   Object and the PCC SHOULD ignore it were it to receive one.

   If a PCC's label database survived the restart of a PCEP session, the
   PCC will include the LABEL-DB-VERSION TLV in its OPEN object, and the
   TLV will contain the last Label Database Version Number received on
   an Label Update from the PCECC in the previous PCEP session.  If a
   PCECC's Label Database survived the restart of a PCEP session, the
   PCECC will include the LABEL-DB-VERSION TLV in its OPEN object and
   the TLV will contain the latest Label Database Version Number.  If a
   PCEP speaker's label database did not survive the restart of a PCEP
   session, the PCEP speaker MUST NOT include the LABEL-DB-VERSION TLV
   in the OPEN object.

   If both PCEP speakers include the LABEL-DB-VERSION TLV in the OPEN
   Object and the TLV values match, the PCECC MAY skip LABEL-DB
   synchronization.  Otherwise, the PCECC MUST perform full LABEL-DB
   synchronization ([I-D.zhao-pce-pcep-extension-for-pce-controller] and
   [I-D.zhao-pce-pcep-extension-pce-controller-sr]) or incremental
   LABEL-DB synchronization (see Section 3.2) to the PCC, In case, the
   PCECC attempts to skip LABEL-DB synchronization, by setting the SYNC
   Flag to 0 on the first Label Update from the PCECC, the PCC MUST send
   back a PCErr with Error-type TBD1 (Label Database Synchronization
   Error) and Error-value 4(Label Database Version mismatch), and close
   the PCEP session.

   If LABEL-DB synchronization is required, then prior to completing the
   initialization phase, the PCC MUST mark any labels in the label
   database that were previously updated by the PCECC as stale.  When
   the PCECC updates a label during LABEL-DB synchronization, if the
   label already exists in the label database, the PCC MUST update the
   label database and clear the stale marker from the label.  When it
   has finished LABEL-DB synchronization, the PCECC MUST immediately
   send an end of synchronization marker.  The end of synchronization
   marker is a Path Computation Label Update (PCLabelUpd) message with a



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   SRP object containing the SYNC flag set to 0 (see Section 4.1) and
   Label as 0 in the LABEL object.  The LABEL-DB-VERSION TLV MUST be
   included in this PCLabelUpd message.  On receiving this Label Update,
   the PCC MUST report all the labels in the label database that are
   still marked as stale to PCECC.

   Note that a PCECC/PCC MAY force LABEL-DB synchronization by not
   including the LABEL-DB-VERSION TLV in its OPEN object.

   Figure 1 shows an example sequence where the LABEL-DB synchronization
   is skipped.

                +-+-+-+                         +-+-+
                |PCECC|                         |PCC|
                +-+-+-+                         +-+-+
                   |                 ,----Open---|
                   |                /   DBv=35   |
                   |--Open--,      /     I=1     |
                   |  DBv=35 \    /              |
                   |    I=1   \  /               |
                   |           \/                |
                   |           /\                |
                   |          /   `------------->| (OK to skip sync)
       (Skip sync) |<--------`                   |
                   |            .                |
                   |            .                |
                   |            .                |
                   |                             |
                   |--PCLabelUpd,DBv=36,SYNC=0-->| (Regular
                   |                             |  Label Update)
                   |--PCLabelUpd,DBv=37,SYNC=0-->| (Regular
                   |                             |  Label Update)
                   |--PCLabelUpd,DBv=38,SYNC=0-->|
                   |                             |

                Figure 1: LABEL-DB synchronization Skipped

   Figure 2 shows an example sequence where the LABEL-DB synchronization
   is performed due to label database version mismatch during the PCEP
   session setup.  Note that the same LABEL-DB synchronization sequence
   would happen if either the PCC or the PCECC would not include the
   LABEL- DB-VERSION TLV in their respective Open messages.









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                 +-+-+-+                         +-+-+
                 |PCECC|                         |PCC|
                 +-+-+-+                         +-+-+
                    |                 ,----Open---|
                    |                /   DBv=35   |
                    |--Open--,      /     I=1     |
                    |  DBv=39 \    /              |
                    |    I=1   \  /               |
                    |           \/                |
                    |           /\                |
                    |          /   `------------->| (Expect sync)
          (Do sync) |<--------`                   |
                    |                             |
                    |--PCLabelUpd,DBv=39,SYNC=1-->| (Sync start)
                    |            .                |
                    |            .                |
                    |            .                |
                    |--PCLabelUpd,DBv=39,SYNC=0-->| (Sync done)
                    |            .                |
                    |            .                |
                    |            .                |
                    |--PCLabelUpd,DBv=40,SYNC=0-->| (Regular
                    |                             |  Label Update)
                    |--PCLabelUpd,DBv=41,SYNC=0-->| (Regular
                    |                             |  Label Update)
                    |--PCLabelUpd,DBv=42,SYNC=0-->|
                    |                             |


               Figure 2: LABEL-DB synchronization Performed

   Figure 3 shows an example sequence where the LABEL-DB synchronization
   is skipped, but because one or both PCEP speakers set the I Flag to
   0, the PCECC does not send LABEL-DB-VERSION TLVs in subsequent
   PCLabelUpd messages to the PCC.  If the current PCEP session
   restarts, the PCEP speakers will have to perform full LABEL-DB
   synchronization, since the PCC does not know the PCECC's latest Label
   Database Version Number information.













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                +-+-+-+                         +-+-+
                |PCECC|                         |PCC|
                +-+-+-+                         +-+-+
                   |                 ,----Open---|
                   |                /   DBv=43   |
                   |--Open--,      /     I=0     |
                   |  DBv=43 \    /              |
                   |    I=0   \  /               |
                   |           \/                |
                   |           /\                |
                   |          /   `------------->| (OK to skip sync)
       (Skip sync) |<--------`                   |
                   |            .                |
                   |            .                |
                   |            .                |
                   |------PCLabelUpd,SYNC=0----->| (Regular
                   |                             |  Label Update)
                   |------PCLabelUpd,SYNC=0----->| (Regular
                   |                             |  Label Update)
                   |------PCLabelUpd,SYNC=0----->|
                   |                             |

   Figure 3: LABEL-DB Synchronization Skipped, no LABEL-DB-VERSION TLVs
                              sent from PCECC

3.2.  Incremental LABEL-DB Synchronization Procedure

   If a PCC restarts and its label database survived, PCECC with
   mismatched Label Database Version Number will send all their Labels
   information (full LABEL-DB) to the PCC, even if only a small number
   of changes happened.  It can take a long time and consume large
   communication channel bandwidth.

   This section extends the idea to only synchronize the delta (changes)
   in case of Label Database Version Number of both PCEP peers is non-
   zero and mismatch.

   If both PCEP speakers include the LABEL-DB-VERSION TLV in the OPEN
   object and the LABEL-DB-VERSION TLV values match, the PCECC MAY skip
   LABEL-DB synchronization.  Otherwise, the PCECC MUST perform LABEL-DB
   synchronization.  Incremental label database synchronization
   capability is advertised on a PCEP session during session startup
   using the DELTA-LABEL-SYNC-CAPABILITY (D) bit in the capabilities TLV
   (see Section 4.2).  Instead of dumping full LABEL-DB to the PCC
   again, the PCECC synchronizes the delta (changes) as described in
   Figure 4 when D flag and I flag is set to 1 by both PCC and PCECC.
   Other combinations of D and I flags setting by PCC and PCECC result
   in full LABEL-DB synchronization procedure as described in



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   [I-D.zhao-pce-pcep-extension-for-pce-controller] and
   [I-D.zhao-pce-pcep-extension-pce-controller-sr].  The PCECC MAY force
   a full LABEL-DB synchronization by setting the D flag to zero in the
   OPEN message.


               +-+-+-+                         +-+-+
               |PCECC|                         |PCC|
               +-+-+-+                         +-+-+
                  |                 ,----Open---|
                  |                /   DBv=35   |
                  |--Open--,      /     I=1     |
                  |  DBv=39 \    /      D=1     |
                  |    I=1   \  /               |
                  |           \/                |
                  |           /\                |
                  |          /   `------------->| (Expect Delta sync)
         (Do sync)|<--------`                   |
         (Delta)  |                             |
                  |                             |
     (Delta       |--PCLabelUpd,DBv=39,SYNC=1-->|
     Sync starts) |            .                |
                  |            .                |
                  |            .                |
                  |            .                |
                  |--PCLabelUpd,DBv=39,SYNC=0-->| (Sync done)
                  |                             |
                  |                             |
                  |--PCLabelUpd,DBv=40,SYNC=0-->| (Regular
                  |                             |  Label Update)
                  |--PCLabelUpd,DBv=41,SYNC=0-->| (Regular
                  |                             |  Label Update)
                  |--PCLabelUpd,DBv=42,SYNC=0-->|
                  |                             |

              Figure 4: Incremental Synchronization Procedure

   As per Section 3.1, the Label Database Version Number is incremented
   each time a change is made to the PCECC's label database.  Each label
   is associated with the DB version at the time of its addition.  This
   is needed to determine which label and what information needs to be
   synchronized in incremental LABEL-DB synchronization.

   It is not necessary for a PCECC to store a complete history of label
   database change, but rather remember the labels (including label
   addition and deletion) that happened between the PCEP session(s)
   restart in order to carry out incremental LABEL-DB synchronization.
   After the synchronization procedure finishes, the PCECC can dump this



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   history information.  In the example shown in Figure 4, the PCECC
   needs to store the label changes that happened between DB Version 35
   to 39 and synchronizes these changes only when performing incremental
   label update.  So a PCECC needs to remember at least the label
   changes that happened after an existing PCEP session with a PCC goes
   down to have any chance of doing incremental synchronization when the
   session is re-established.

   If a PCECC finds out it does not have sufficient information to
   complete incremental synchronization after advertising incremental
   LABEL-DB synchronization capability, it MUST send a PCErr with Error-
   Type TBD1 and Error-Value 5 'A PCECC indicates to a PCC that it can
   not complete the LABEL-DB synchronization' and terminate the session.
   The PCECC SHOULD re-establish the session with the D bit set to 0 in
   the OPEN message.

   The other procedures and error checks remain unchanged from the
   default LABEL-DB synchronization defined in
   [I-D.zhao-pce-pcep-extension-for-pce-controller] and
   [I-D.zhao-pce-pcep-extension-pce-controller-sr].

4.  PCEP Extensions

4.1.  Extension of SRP object

   SRP object extension for SYNC flag to specify the LABEL-DB
   synchronization operation is defined in
   [I-D.zhao-pce-pcep-extension-for-pce-controller].

4.2.  Extension of PCECC Capability sub-TLV

   PCECC Capability sub-TLV is defined in
   [I-D.zhao-pce-pcep-extension-for-pce-controller].  This draft defines
   a new 'INCLUDE-LABEL-DB-VERSION' flag (I bit) to specify the label
   database version capability and 'DELTA-LABEL-SYNC-CAPABILITY' to
   specify the incremental label database synchronization capability.

   The TLV format is as per [RFC5440].  The format of the PCECC
   Capability sub-TLV is shown Figure 5:












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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=4           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                             Flags                       |D|I|S|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                    Figure 5: PCECC Capability sub-TLV

   I (INCLUDE-LABEL-DB-VERSION - 1 bit): if set to 1 by both PCEP
   Speakers, the PCECC will include the LABEL-DB-VERSION TLV in each
   LABEL Object.

   D (DELTA-LABEL-SYNC-CAPABILITY - 1 bit): if set to 1 by a PCEP
   speaker, it indicates that the PCEP speaker allows incremental
   (delta) LABEL-DB synchronization.

4.3.  New LABEL-DB-VERSION TLV

   The Label Database Version Number (LABEL-DB-VERSION) TLV is an
   optional TLV that MAY be included in the OPEN object and the LABEL
   object.

   The TLV format is as per [RFC5440].  The format of the LABEL-DB-
   VERSION 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=[TBD3]         |            Length=8           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                 Label Database Version Number                 |
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Figure 6: LABEL-DB-VERSION TLV format

   The type of the TLV is [TBD3] and it has a fixed length of 8 octets.
   The value contains a 64-bit unsigned integer, representing the Label
   Database Version Number.








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5.  IANA Considerations

5.1.  PCEP TLV Type Indicators

   IANA is requested to confirm the early allocation of the following
   TLV Type Indicator values within the "PCEP TLV Type Indicators" sub-
   registry of the PCEP Numbers registry, and to update the reference in
   the registry to point to this document, when it is an RFC:

            Value          Meaning               Reference
            [TBD]          LABEL-DB-VERSION TLV  This document

5.2.  PCECC-CAPABILITY sub-TLV

   [I-D.zhao-pce-pcep-extension-for-pce-controller] defines the PCECC-
   CAPABILITY sub-TLV and
   [I-D.zhao-pce-pcep-extension-pce-controller-sr] extends this sub-TLV
   to add PCECC-SR-CAPABILITY.

   Requests that IANA creates a registry to manage the value of the new
   PCECC-CAPABILITY sub-TLV's Flag field.  IANA is requested to allocate
   a new bits in the PCECC-CAPABILITY sub-TLV Flag Field registry, as
   follows:

       Bit            Description                     Reference
       TBD            I (INCLUDE-LABEL-DB-VERSION )   This document
       TBD            D (DELTA-LABEL-SYNC-CAPABILITY) This document

6.  Manageability Considerations

   All manageability requirements and considerations listed in
   [RFC5440], [RFC8231] and
   [I-D.zhao-pce-pcep-extension-for-pce-controller] apply to PCEP
   protocol extensions defined in this document.  In addition,
   requirements and considerations listed in this section apply.

6.1.  Control of Function and Policy

6.2.  Information and Data Models

6.3.  Liveness Detection and Monitoring

6.4.  Verify Correct Operations








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6.5.  Requirements On Other Protocols

6.6.  Impact On Network Operations

7.  Security Considerations

   The security considerations listed in [RFC8231] and
   [I-D.zhao-pce-pcep-extension-for-pce-controller] apply to this
   document as well.  Securing the PCEP session using Transport Layer
   Security (TLS) [RFC8253], as per the recommendations and best current
   practices in [RFC7525], is RECOMMENDED.

8.  Acknowledgements

   This document borrows some of the structure and text from [RFC8253],
   and would like to thanks the authors and contributors of the
   document.

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>.

   [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>.

   [I-D.zhao-pce-pcep-extension-for-pce-controller]
              Zhao, Q., Li, Z., Dhody, D., Karunanithi, S., Farrel, A.,
              and C. Zhou, "PCEP Procedures and Protocol Extensions for
              Using PCE as a Central Controller (PCECC) of LSPs", draft-
              zhao-pce-pcep-extension-for-pce-controller-06 (work in
              progress), October 2017.



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9.2.  Informative References

   [RFC7525]  Sheffer, Y., Holz, R., and P. Saint-Andre,
              "Recommendations for Secure Use of Transport Layer
              Security (TLS) and Datagram Transport Layer Security
              (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
              2015, <https://www.rfc-editor.org/info/rfc7525>.

   [RFC8233]  Dhody, D., Wu, Q., Manral, V., Ali, Z., and K. Kumaki,
              "Extensions to the Path Computation Element Communication
              Protocol (PCEP) to Compute Service-Aware Label Switched
              Paths (LSPs)", RFC 8233, DOI 10.17487/RFC8233, September
              2017, <https://www.rfc-editor.org/info/rfc8233>.

   [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>.

   [RFC8283]  Farrel, A., Ed., Zhao, Q., Ed., Li, Z., and C. Zhou, "An
              Architecture for Use of PCE and the PCE Communication
              Protocol (PCEP) in a Network with Central Control",
              RFC 8283, DOI 10.17487/RFC8283, December 2017,
              <https://www.rfc-editor.org/info/rfc8283>.

   [I-D.zhao-pce-pcep-extension-pce-controller-sr]
              Zhao, Q., Li, Z., Dhody, D., Karunanithi, S., Farrel, A.,
              and C. Zhou, "PCEP Procedures and Protocol Extensions for
              Using PCE as a Central Controller (PCECC) of SR-LSPs",
              draft-zhao-pce-pcep-extension-pce-controller-sr-01 (work
              in progress), October 2017.

Authors' Addresses

   Udayasree Palle
   Huawei Technologies
   Divyashree Techno Park, Whitefield
   Bangalore, Karnataka  560066
   India

   EMail: udayasreereddy@gmail.com









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   Dhruv Dhody
   Huawei Technologies
   Divyashree Techno Park, Whitefield
   Bangalore, Karnataka  560066
   India

   EMail: dhruv.ietf@gmail.com


   Satish Karunanithi
   Huawei Technologies
   Divyashree Techno Park, Whitefield
   Bangalore, Karnataka  560066
   India

   EMail: satishk@huawei.com



































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