[Docs] [txt|pdf|xml] [Tracker] [Email] [Nits]

Versions: 00 01 02

PCE Working Group                                               U. Palle
Internet-Draft                                                  D. Dhody
Intended status: Experimental                        Huawei Technologies
Expires: November 16, 2016                                  May 15, 2016


       LABEL-DB Synchronization Procedures for a PCE as a central
                           controller(PCECC)
               draft-palle-pce-controller-labeldb-sync-00

Abstract

   [I-D.zhao-pce-pcep-extension-for-pce-controller] specify the
   procedures and PCEP protocol extensions for using the PCE as the
   central controller [I-D.zhao-teas-pce-control-function] 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 PCECC.  This draft specify the label database synchronization
   mechanism for managing of label database (LABEL-DB) at node (PCC)
   aligning with LABEL-DB at PCECC on initial session UP or session flap
   and specifies the required Path Computation Element Communication
   Protocol (PCEP) 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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

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

   This Internet-Draft will expire on November 16, 2016.







Palle & Dhody           Expires November 16, 2016               [Page 1]


Internet-Draft                LABEL-DB-SYNC                     May 2016


Copyright Notice

   Copyright (c) 2016 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
   (http://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  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  LABEL-DB Synchronization  . . . . . . . . . . . . . . . . . .   3
   3.  Full LABEL-DB Synchronization procedure . . . . . . . . . . .   3
   4.  Optimizations for LABEL-DB Synchronization  . . . . . . . . .   6
     4.1.  LABEL-DB Synchronization Avoidance Procedure  . . . . . .   6
     4.2.  Incremental LABEL-DB Synchronization Procedure  . . . . .  10
   5.  PCEP Extensions . . . . . . . . . . . . . . . . . . . . . . .  12
     5.1.  Extension of SRP object . . . . . . . . . . . . . . . . .  12
     5.2.  Extension of PCECC Capability TLV . . . . . . . . . . . .  13
     5.3.  New LABEL-DB-VERSION TLV  . . . . . . . . . . . . . . . .  13
   6.  Manageability Considerations  . . . . . . . . . . . . . . . .  14
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  14
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  14
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  14
     10.2.  Informative References . . . . . . . . . . . . . . . . .  15
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  15

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 [I-D.zhao-teas-pce-control-function] and user
   cases where LSPs are calculated/setup/initiated/downloaded through
   extending the existing PCE architectures and PCEP.

   Labels downloaded to forwarding entries requires a reliable
   synchronization mechanism between the path computation clients (PCCs)
   and the PCECC.  This draft specify the PCECC maintenance of label



Palle & Dhody           Expires November 16, 2016               [Page 2]


Internet-Draft                LABEL-DB-SYNC                     May 2016


   database per session, and describes the label database(LABEL-DB)
   synchronization mechanism for managing of label database at node
   (PCC) aligning with label database at PCECC on initial session UP or
   session flap and specifies the required Path Computation Element
   Communication Protocol (PCEP) extensions.

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

1.1.  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 [RFC2119].

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.  [I-D.ietf-pce-stateful-pce]
   describes the basic mechanism for LSP state synchronization.
   [I-D.ietf-pce-stateful-sync-optimizations] describes the
   optimizations for LSP state synchronization.

   By default a Full LABEL-DB is performed from PCECC to PCC on Initial
   session UP or every session flap.  see Section 3 for detail
   procedures.

   But a Full LABEL-DB synchronization is not always necessary following
   a PCEP session restart and 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 4 for
   detail procedures.

3.  Full LABEL-DB Synchronization procedure

   During Full LABEL-DB Synchronization, a PCECC first takes a snapshot
   of the label database for the session, then sends this snapshot to
   the PCC in a sequence of Label Update message (PCLabelUpd message
   defined in [I-D.zhao-pce-pcep-extension-for-pce-controller]).  Each




Palle & Dhody           Expires November 16, 2016               [Page 3]


Internet-Draft                LABEL-DB-SYNC                     May 2016


   PCLabelUpd message sent during LABEL-DB Synchronization has the SYNC
   Flag in the SRP Object(see Section 5.1) set to 1.

   The end of synchronization marker is a PCLabelUpd message with the
   SYNC Flag set to 0 for SRP Object with Label equal to reserved value
   0 in the LABEL object
   ([I-D.zhao-pce-pcep-extension-for-pce-controller]).  If the PCECC has
   no label to synchronize, it will only send the end of synchronization
   marker.

   A PCECC SHOULD NOT send PCUpd messages to a PCC before LABEL-DB
   Synchronization is complete.

   Either the PCECC or the PCC MAY terminate the session using the PCEP
   session termination procedures during the LABEL-DB synchronization
   phase.  If the session is terminated, the PCC MUST clean up label(s)
   it received from this PCECC.  The session reestablishment MUST be re-
   attempted as per the procedures defined in [RFC5440], including use
   of a back-off timer.

   The PCC does not send positive acknowledgements for properly received
   label database synchronization messages.  It MUST respond with a
   PCErr message with Error-type TBD1 (Label Database Synchronization
   Error) and Error-value 1 (indicating an error in processing the
   PCLabelUpd) if it encounters a problem with the Label Update it
   received from the PCECC and it MUST terminate the session.

   If the PCECC encounters a problem which prevents it from completing
   the label transfer, it MUST send a PCErr message with Error-type TBD1
   (Label Database Synchronization Error) and Error-value 2 (indicating
   an internal PCECC Error) to the PCC and terminate the session.

   The successful LABEL-DB Synchronization sequence is shown in
   Figure 1.

















Palle & Dhody           Expires November 16, 2016               [Page 4]


Internet-Draft                LABEL-DB-SYNC                     May 2016


          +-+-+-+                         +-+-+
          |PCECC|                         |PCC|
          +-+-+-+                         +-+-+
             |                             |
             |-----PCLabelUpd, SYNC=1----->| (Sync start)
             |                             |
             |-----PCLabelUpd, SYNC=1----->|
             |            .                |
             |            .                |
             |            .                |
             |-----PCLabelUpd, SYNC=1----->|
             |            .                |
             |            .                |
             |            .                |
             |                             |
             |-----PCLabelUpd, SYNC=0----->| (End of sync marker
             |                             |  Label Update
             |                             |  LABEL=0)
             |                             | (Sync done)

               Figure 1: Successful LABEL-DB synchronization

   The sequence where the PCC fails during the LABEL-DB Synchronization
   phase is shown in Figure 2.

            +-+-+-+                           +-+-+
            |PCECC|                           |PCC|
            +-+-+-+                           +-+-+
               |                                |
               |--------PCLabelUpd, SYNC=1----->| (Sync start)
               |                                |
               |--------PCLabelUpd, SYNC=1----->|
               |               .                |
               |               .                |
               |               .                |
               |--------PCLabelUpd, SYNC=1----->|
               |                                |
               |---PCLabelUpd, SYNC=1          |
               |            \    ,----PCErr ----|
               |             \  /               |
               |              \/                |
               |              /\                |
               |             /   `------------->| (Ignored)
               |<-----------`                       |


          Figure 2: Failed LABEL-DB synchronization(PCC failure)




Palle & Dhody           Expires November 16, 2016               [Page 5]


Internet-Draft                LABEL-DB-SYNC                     May 2016


   The sequence where the PCECC fails during the LABEL-DB
   Synchronization phase is shown in Figure 3.

              +-+-+-+                         +-+-+
              |PCECC|                         |PCC|
              +-+-+-+                         +-+-+
                 |                             |
                 |-----PCLabelUpd, SYNC=1----->| (Sync start)
                 |                             |
                 |-----PCLabelUpd, SYNC=1----->|
                 |            .                |
                 |            .                |
                 |            .                |
                 |----------- PCErr=? -------->|
                 |                             |


         Figure 3: Failed LABEL-DB synchronization(PCECC failure)

4.  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.

4.1.  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 5.3), 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.




Palle & Dhody           Expires November 16, 2016               [Page 6]


Internet-Draft                LABEL-DB-SYNC                     May 2016


   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 TLV (see Section 5.2).  The PCEP peer MAY
   include the SPEAKER-ENTITY-ID TLV described in
   [I-D.ietf-pce-stateful-sync-optimizations] 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 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 (see Section 3) or incremental LABEL-DB
   synchronization (see Section 4.2) to the PCC, Incase, 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



Palle & Dhody           Expires November 16, 2016               [Page 7]


Internet-Draft                LABEL-DB-SYNC                     May 2016


   SRP object containing the SYNC flag set to 0 (see Section 5.1) 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 purge any labels from the label database that are still
   marked as stale.

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

   Figure 4 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 4: LABEL-DB synchronization Skipped

   Figure 5 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.









Palle & Dhody           Expires November 16, 2016               [Page 8]


Internet-Draft                LABEL-DB-SYNC                     May 2016


                 +-+-+-+                         +-+-+
                 |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)
                    |            .                |(Purge Label
                    |            .                | if applicable)
                    |            .                |
                    |--PCLabelUpd,DBv=40,SYNC=0-->| (Regular
                    |                             |  Label Update)
                    |--PCLabelUpd,DBv=41,SYNC=0-->| (Regular
                    |                             |  Label Update)
                    |--PCLabelUpd,DBv=42,SYNC=0-->|
                    |                             |


               Figure 5: LABEL-DB synchronization Performed

   Figure 6 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.













Palle & Dhody           Expires November 16, 2016               [Page 9]


Internet-Draft                LABEL-DB-SYNC                     May 2016


                +-+-+-+                         +-+-+
                |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 6: LABEL-DB Synchronization Skipped, no LABEL-DB-VERSION TLVs
                              sent from PCECC

4.2.  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 5.2).  Instead of dumping full LABEL-DB to the PCC
   again, the PCECC synchronizes the delta (changes) as described in
   Figure 7 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 Section 3.



Palle & Dhody           Expires November 16, 2016              [Page 10]


Internet-Draft                LABEL-DB-SYNC                     May 2016


   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=0   \  /               |
                  |           \/                |
                  |           /\                |
                  |          /   `------------->| (Expect Delta sync)
         (Do sync)|<--------`                   | (DONOT Purge Label)
         (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 7: Incremental Synchronization Procedure

   As per Section 4.1, 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
   history information.  In the example shown in Figure 7, the PCECC
   needs to store the label changes that happened between DB Version 35



Palle & Dhody           Expires November 16, 2016              [Page 11]


Internet-Draft                LABEL-DB-SYNC                     May 2016


   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 full
   LABEL-DB synchronization defined in Section 3.

5.  PCEP Extensions

5.1.  Extension of SRP object

   SRP object is defined in [I-D.ietf-pce-stateful-pce] and extended in
   [I-D.ietf-pce-pce-initiated-lsp].  This draft defines a new 'SYNC'
   flag (S bit) to specify the LABEL-DB synchronization operation.

   The format of the SRP object is shown Figure 8:



      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                          Flags                            |S|R|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                        SRP-ID-number                          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     //                      Optional TLVs                          //
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                        Figure 8: SRP Object format

   S (SYNC - 1 bit): The S Flag MUST be set to 1 on each PCLabelUpd sent
   from a PCECC during LABEL-DB Synchronization.  The S Flag MUST be set
   to 0 in other messages sent from the PCECC.




Palle & Dhody           Expires November 16, 2016              [Page 12]


Internet-Draft                LABEL-DB-SYNC                     May 2016


5.2.  Extension of PCECC Capability TLV

   PCECC Capability 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 format of the PCECC Capability TLV is shown Figure 9:



      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 9: PCECC Capability 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.

5.3.  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 format of the LABEL-DB-VERSION TLV is shown in the following
   figure:












Palle & Dhody           Expires November 16, 2016              [Page 13]


Internet-Draft                LABEL-DB-SYNC                     May 2016


      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 10: 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.

6.  Manageability Considerations

   TBD

7.  Security Considerations

   TBD

8.  IANA Considerations

   TBD

9.  Acknowledgements

   This document borrows some of the structure and text from
   [I-D.ietf-pce-stateful-sync-optimizations], and would like to thanks
   the authors and contributors of the document.

10.  References

10.1.  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,
              <http://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,
              <http://www.rfc-editor.org/info/rfc5440>.





Palle & Dhody           Expires November 16, 2016              [Page 14]


Internet-Draft                LABEL-DB-SYNC                     May 2016


   [I-D.ietf-pce-stateful-pce]
              Crabbe, E., Minei, I., Medved, J., and R. Varga, "PCEP
              Extensions for Stateful PCE", draft-ietf-pce-stateful-
              pce-14 (work in progress), March 2016.

   [I-D.zhao-pce-pcep-extension-for-pce-controller]
              Zhao, Q., Li, Z., Dhody, D., 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-03 (work in progress), March
              2016.

10.2.  Informative References

   [I-D.zhao-teas-pce-control-function]
              Farrel, A., Zhao, Q., Li, Z., and C. Zhou, "An
              Architecture for Use of PCE and PCEP in a Network with
              Central Control", draft-zhao-teas-pce-control-function-00
              (work in progress), May 2016.

   [I-D.ietf-pce-pce-initiated-lsp]
              Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP
              Extensions for PCE-initiated LSP Setup in a Stateful PCE
              Model", draft-ietf-pce-pce-initiated-lsp-05 (work in
              progress), October 2015.

   [I-D.ietf-pce-stateful-sync-optimizations]
              Crabbe, E., Minei, I., Medved, J., Varga, R., Zhang, X.,
              and D. Dhody, "Optimizations of Label Switched Path State
              Synchronization Procedures for a Stateful PCE", draft-
              ietf-pce-stateful-sync-optimizations-05 (work in
              progress), April 2016.

Authors' Addresses

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

   EMail: udayasree.palle@huawei.com









Palle & Dhody           Expires November 16, 2016              [Page 15]


Internet-Draft                LABEL-DB-SYNC                     May 2016


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

   EMail: dhruv.ietf@gmail.com












































Palle & Dhody           Expires November 16, 2016              [Page 16]


Html markup produced by rfcmarkup 1.126, available from https://tools.ietf.org/tools/rfcmarkup/