PCE Working Group                                               D. Dhody
Internet-Draft                                                    Y. Lee
Intended status: Standards Track                     Huawei Technologies
Expires: April 30, 2015                                    D. Ceccarelli
                                                                Ericsson
                                                        October 27, 2014


                PCEP Extension for Transporting TE Data
                draft-dhodylee-pce-pcep-te-data-extn-01

Abstract

   In order to compute and provide optimal paths, Path Computation
   Elements (PCEs) require an accurate and timely Traffic Engineering
   Database (TED).  Traditionally this TED has been obtained from a link
   state routing protocol supporting traffic engineering extensions.

   This document extends the Path Computation Element Communication
   Protocol (PCEP) with TED population capability.

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 April 30, 2015.

Copyright Notice

   Copyright (c) 2014 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



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   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
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Applicability . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Requirements for PCEP extension . . . . . . . . . . . . . . .   4
   5.  New Functions to Support TED via PCEP . . . . . . . . . . . .   5
   6.  Overview of Extension to PCEP . . . . . . . . . . . . . . . .   5
     6.1.  New Messages  . . . . . . . . . . . . . . . . . . . . . .   5
     6.2.  Capability Advertisement  . . . . . . . . . . . . . . . .   6
     6.3.  Initial TED Synchronization . . . . . . . . . . . . . . .   6
       6.3.1.  Optimizations for TED Synchronization . . . . . . . .   9
     6.4.  TE Report . . . . . . . . . . . . . . . . . . . . . . . .   9
   7.  Transport . . . . . . . . . . . . . . . . . . . . . . . . . .   9
   8.  PCEP Messages . . . . . . . . . . . . . . . . . . . . . . . .   9
     8.1.  TE Report Message . . . . . . . . . . . . . . . . . . . .  10
     8.2.  The PCErr Message . . . . . . . . . . . . . . . . . . . .  10
   9.  Objects and TLV . . . . . . . . . . . . . . . . . . . . . . .  11
     9.1.  Open Object . . . . . . . . . . . . . . . . . . . . . . .  11
       9.1.1.  TED Capability TLV  . . . . . . . . . . . . . . . . .  11
     9.2.  TE Object . . . . . . . . . . . . . . . . . . . . . . . .  12
       9.2.1.  Routing Universe TLV  . . . . . . . . . . . . . . . .  13
       9.2.2.  Local TE Node Descriptors TLV . . . . . . . . . . . .  14
       9.2.3.  Remote TE Node Descriptors TLV  . . . . . . . . . . .  15
       9.2.4.  TE Node Descriptors Sub-TLVs  . . . . . . . . . . . .  15
       9.2.5.  TE Link Descriptors TLV . . . . . . . . . . . . . . .  16
       9.2.6.  TE Node Attributes TLV  . . . . . . . . . . . . . . .  17
       9.2.7.  TE Link Attributes TLV  . . . . . . . . . . . . . . .  18
   10. Other Considerations  . . . . . . . . . . . . . . . . . . . .  20
     10.1.  Inter-AS Links . . . . . . . . . . . . . . . . . . . . .  20
   11. Security Considerations . . . . . . . . . . . . . . . . . . .  20
   12. Manageability Considerations  . . . . . . . . . . . . . . . .  20
     12.1.  Control of Function and Policy . . . . . . . . . . . . .  20
     12.2.  Information and Data Models  . . . . . . . . . . . . . .  20
     12.3.  Liveness Detection and Monitoring  . . . . . . . . . . .  20
     12.4.  Verify Correct Operations  . . . . . . . . . . . . . . .  20
     12.5.  Requirements On Other Protocols  . . . . . . . . . . . .  20
     12.6.  Impact On Network Operations . . . . . . . . . . . . . .  20
   13. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  20
   14. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  21
   15. References  . . . . . . . . . . . . . . . . . . . . . . . . .  21
     15.1.  Normative References . . . . . . . . . . . . . . . . . .  21



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     15.2.  Informative References . . . . . . . . . . . . . . . . .  21
   Appendix A.  Contributor Addresses  . . . . . . . . . . . . . . .  23

1.  Introduction

   In Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS),
   a Traffic Engineering Database (TED) is used in computing paths for
   connection oriented packet services and for circuits.  The TED
   contains all relevant information that a Path Computation Element
   (PCE) needs to perform its computations.  It is important that the
   TED be complete and accurate each time, the PCE performs a path
   computation.

   In MPLS and GMPLS, interior gateway routing protocols (IGPs) have
   been used to create and maintain a copy of the TED at each node
   running the IGP.  One of the benefits of the PCE architecture
   [RFC4655] is the use of computationally more sophisticated path
   computation algorithms and the realization that these may need
   enhanced processing power not necessarily available at each node
   participating in an IGP.

   Section 4.3 of [RFC4655] describes the potential load of the TED on a
   network node and proposes an architecture where the TED is maintained
   by the PCE rather than the network nodes.  However, it does not
   describe how a PCE would obtain the information needed to populate
   its TED.  PCE may construct its TED by participating in the IGP
   ([RFC3630]  and [RFC5305]  for MPLS-TE; [RFC4203]  and [RFC5307] for
   GMPLS).  An alternative is offered by BGP-LS
   [I-D.ietf-idr-ls-distribution] .

   [I-D.lee-pce-transporting-te-data] proposes some other approaches for
   creating and maintaining the TED directly on a PCE as an alternative
   to IGPs and BGP flooding and investigate the impact from the PCE,
   routing protocol, and node perspectives.

   [RFC5440] describes the specifications for the Path Computation
   Element Communication Protocol (PCEP).  PCEP specifies the
   communication between a Path Computation Client (PCC) and a Path
   Computation Element (PCE), or between two PCEs based on the PCE
   architecture [RFC4655].

   This document specifies a PCEP extension for TED population
   capability to support functionalities described in
   [I-D.lee-pce-transporting-te-data].







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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.  Terminology

   The terminology is as per [RFC4655] and [RFC5440].

3.  Applicability

   As per [I-D.lee-pce-transporting-te-data], the mechanism specified in
   this draft is applicable to:

   o  Where there is no IGP-TE or BGP-LS running at the PCE to learn
      TED.

   o  Where there is IGP-TE or BGP-LS running but with a need for a
      faster TED population and convergence at the PCE.

      *  A PCE may receive partial information (say basic TE) from IGP-
         TE and other information (optical and impairment) from PCEP.

      *  A PCE may receive full information from both IGP-TE and PCEP.

   A PCC may further choose to send only local TE information or both
   local and remote learned TED information.

   How a PCE manages the TED information is implementation specific and
   thus out of scope of this document.

4.  Requirements for PCEP extension

   Following key requirements associated with TED population are
   identified for PCEP:

   1.  The PCEP speaker supporting this draft MUST be a mechanism to
       advertise the TED capability.

   2.  PCC supporting this draft MUST have the capability to report the
       TED to the PCE.  This includes self originated TE information and
       remote TE information learned via routing protocols.  PCC MUST be
       capable to do the initial bulk sync at the time of session
       initialization as well as changes to TED after.

   3.  A PCE MAY learn TED from PCEP as well as from existing mechanism
       like IGP-TE/BGP-LS.  PCEP extension MUST have a mechanism to link



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       the TED information learned via other means.  There MUST NOT be
       any changes to the existing TED population mechanism via IGP-TE/
       BGP-LS.  PCEP extension SHOULD keep the TE properties in a
       routing protocol (IGP-TE or BGP-LS) neutral way, such that an
       implementation which do want to learn about a Link-state topology
       do not need to know about any OSPF or IS-IS or BGP protocol
       specifics.

   4.  It SHOULD be possible to encode only the changes in TED
       properties (after the initial sync) in PCEP messages.

   5.  The same mechanism should be used for both MPLS TE as well as
       GMPLS, optical and impairment aware properties.

   6.  The extension in this draft SHOULD be extensible to support
       various architecture options listed in
       [I-D.lee-pce-transporting-te-data].

5.  New Functions to Support TED via PCEP

   Several new functions are required in PCEP to support TED population.
   A function can be initiated either from a PCC towards a PCE (C-E) or
   from a PCE towards a PCC (E-C).  The new functions are:

   o  Capability advertisement (E-C,C-E): both the PCC and the PCE must
      announce during PCEP session establishment that they support PCEP
      extensions for TED population defined in this document.

   o  TE synchronization (C-E): after the session between the PCC and a
      PCE is initialized, the PCE must learn PCC's TED before it can
      perform path computations.  In case of stateful PCE it is
      RECOMENDED that this operation be done before LSP state
      synchronization.

   o  TE Report (C-E): a PCC sends a TE report to a PCE whenever the TED
      changes.

6.  Overview of Extension to PCEP

6.1.  New Messages

   In this document, we define a new PCEP messages called TE Report
   (TERpt), a PCEP message sent by a PCC to a PCE to report TED.  Each
   TE Report in a TERpt message can contain the TE node or TE Link
   properties.  An unique PCEP specific TE identifier (TE-ID) is also
   carried in the message to identify the TE node or link and that
   remains constant for the lifetime of a PCEP session.  This identifier
   on its own is sufficient when no IGP-TE or BGP-LS running in the



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   network for PCE to learn TED.  Incase PCE learns some information
   from PCEP and some from the existing mechanism, the PCC SHOULD
   include the mapping of IGP-TE or BGP-LS identifier to map the TED
   information populated via PCEP with IGP-TE/BGP-LS.  See Section 8.1
   for details.

6.2.  Capability Advertisement

   During PCEP Initialization Phase, PCEP Speakers (PCE or PCC)
   advertise their support of TED population PCEP extensions.  A PCEP
   Speaker includes the "TED Capability" TLV, described in Section 9, in
   the OPEN Object to advertise its support for PCEP TED extensions.
   The presence of the TED Capability TLV in PCC's OPEN Object indicates
   that the PCC is willing to send TE Reports whenever local TE
   information changes.  The presence of the TED Capability TLV in PCE's
   OPEN message indicates that the PCE is interested in receiving TE
   Reports whenever local TE changes.

   The PCEP protocol extensions for TED population MUST NOT be used if
   one or both PCEP Speakers have not included the TED Capability TLV in
   their respective OPEN message.  If the PCE that supports the
   extensions of this draft but did not advertise this capability, then
   upon receipt of a PCRpt message from the PCC, it SHOULD generate a
   PCErr with error-type 19 (Invalid Operation), error-value TBD1
   (Attempted TE Report if TED capability was not advertised) and it
   will terminate the PCEP session.

   The TE reports sent by PCC MAY carry the remote TE information
   learned via existing means like IGP-TE and BGP-LS only if both PCEP
   Speakers set the R (remote) Flag in the "TED Capability" TLV to
   'Remote Allowed (R Flag = 1)'.  If this is not the case and TE
   reports carry remote TE information, then a PCErr with error-type 19
   (Invalid Operation) and error-value TBD1 (Attempted TE Report if TED
   capability was not advertised) and it will terminate the PCEP
   session.

6.3.  Initial TED Synchronization

   The purpose of TED Synchronization is to provide a checkpoint-in-
   time state replica of a PCC's TED in a PCE.  State Synchronization is
   performed immediately after the Initialization phase (see
   [RFC5440]]).  In case of stateful PCE ([I-D.ietf-pce-stateful-pce])
   it is RECOMENDED that the TED synchronization should be done before
   LSP state synchronization.

   During TED Synchronization, a PCC first takes a snapshot of the state
   of its TED, then sends the snapshot to a PCE in a sequence of TE
   Reports.  Each TE Report sent during TE Synchronization has the SYNC



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   Flag in the TE Object set to 1.  The end of synchronization marker is
   a TERpt message with the SYNC Flag set to 0 for an TE Object with
   TED-ID equal to the reserved value 0.  If the PCC has no TED state to
   synchronize, it will only send the end of synchronization marker.

   Either the PCE or the PCC MAY terminate the session using the PCEP
   session termination procedures during the synchronization phase.  If
   the session is terminated, the PCE MUST clean up state it received
   from this PCC.  The session re-establishment MUST be re-attempted per
   the procedures defined in [RFC5440], including use of a back-off
   timer.

   If the PCC encounters a problem which prevents it from completing the
   TED population, it MUST send a PCErr message with error-type TBD2 (TE
   Synchronization Error) and error-value 5 (indicating an internal PCC
   error) to the PCE and terminate the session.

   The PCE does not send positive acknowledgements for properly received
   TED synchronization messages.  It MUST respond with a PCErr message
   with error-type TBD2 (TE Synchronization Error) and error-value 1
   (indicating an error in processing the TERpt) if it encounters a
   problem with the TE Report it received from the PCC and it MUST
   terminate the session.

   The TE reports may carry local as well as remote TED information
   depending on the R flag in TED capability TLV.

   The successful TED Synchronization sequences is shown in Figure 1.























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                   +-+-+                    +-+-+
                   |PCC|                    |PCE|
                   +-+-+                    +-+-+
                     |                        |
                     |-----TERpt, SYNC=1----->| (Sync start)
                     |                        |
                     |-----TERpt, SYNC=1----->|
                     |            .           |
                     |            .           |
                     |            .           |
                     |-----TERpt, SYNC=1----->|
                     |            .           |
                     |            .           |
                     |            .           |
                     |                        |
                     |-----TERpt, SYNC=0----->| (End of sync marker
                     |                        |  TE Report
                     |                        |  for TED-ID=0)
                     |                        | (Sync done)


                Figure 1: Successful state synchronization

   The sequence where the PCE fails during the TED Synchronization phase
   is shown in Figure 2.

                   +-+-+                    +-+-+
                   |PCC|                    |PCE|
                   +-+-+                    +-+-+
                     |                        |
                     |-----TERpt, SYNC=1----->|
                     |                        |
                     |-----TERpt, SYNC=1----->|
                     |            .           |
                     |            .           |
                     |            .           |
                     |-----TERpt, SYNC=1----->|
                     |                        |
                     |-TERpt, SYNC=1          |
                     |         \    ,-PCErr---|
                     |          \  /          |
                     |           \/           |
                     |           /\           |
                     |          /   `-------->| (Ignored)
                     |<--------`              |


            Figure 2: Failed TED synchronization (PCE failure)



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   The sequence where the PCC fails during the TED Synchronization phase
   is shown in Figure 3.

                 +-+-+                    +-+-+
                 |PCC|                    |PCE|
                 +-+-+                    +-+-+
                   |                        |
                   |-----TERpt, SYNC=1----->|
                   |                        |
                   |-----TERpt, SYNC=1----->|
                   |            .           |
                   |            .           |
                   |            .           |
                   |-------- PCErr--------->|
                   |                        |


            Figure 3: Failed TED synchronization (PCC failure)

6.3.1.  Optimizations for TED Synchronization

   TBD

6.4.  TE Report

   The PCC MUST report any changes in the TEDB to the PCE by sending a
   TE Report carried on a TERpt message to the PCE, indicating that the
   TE state.  Each TE node and TE Link would be uniquely identified by a
   PCEP TE identifier (TE-ID).  The TE reports may carry local as well
   as remote TED information depending on the R flag in TED capability
   TLV.  In case R flag is set, It MAY also include the mapping of IGP-
   TE or BGP-LS identifier to map the TED information populated via PCEP
   with IGP-TE/BGP-LS.

   More details about TERpt message are in Section 8.1.

7.  Transport

   A permanent PCEP session MUST be established between a PCE and PCC
   supporting TED population via PCEP.  In the case of session failure,
   session re-establishment MUST be re-attempted per the procedures
   defined in [RFC5440].

8.  PCEP Messages

   As defined in [RFC5440], a PCEP message consists of a common header
   followed by a variable-length body made of a set of objects that can
   be either mandatory or optional.  An object is said to be mandatory



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   in a PCEP message when the object must be included for the message to
   be considered valid.  For each PCEP message type, a set of rules is
   defined that specify the set of objects that the message can carry.
   An implementation MUST form the PCEP messages using the object
   ordering specified in this document.

8.1.  TE Report Message

   A PCEP TE Report message (also referred to as TERpt message) is a
   PCEP message sent by a PCC to a PCE to report the TED state.  A TERpt
   message can carry more than one TE Reports.  The Message-Type field
   of the PCEP common header for the PCRpt message is set to [TBD3].

   The format of the PCRpt message is as follows:

   <TERpt Message> ::= <Common Header>
                       <te-report-list>
   Where:

   <te-report-list> ::= <TE>[<te-report-list>]


   The TE object is a mandatory object which carries TE information of a
   TE node or a TE link.  Each TE object has an unique TE-ID as
   described in Section 9.2.  If the TE object is missing, the receiving
   PCE MUST send a PCErr message with Error-type=6 (Mandatory Object
   missing) and Error-value=[TBD4] (TE object missing).

   A PCE may choose to implement a limit on the TE information a single
   PCC can populate.  If a TERpt is received that causes the PCE to
   exceed this limit, it MUST send a PCErr message with error-type 19
   (invalid operation) and error-value 4 (indicating resource limit
   exceeded) in response to the TERpt message triggering this condition
   and MAY terminate the session.

8.2.  The PCErr Message

   If a PCEP speaker has advertised the TED capability on the PCEP
   session, the PCErr message MAY include the TE object.  If the error
   reported is the result of an TE report, then the TE-ID number MUST be
   the one from the TERpt that triggered the error.

   The format of a PCErr message from [RFC5440] is extended as follows:

   The format of the PCRpt message is as follows:






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   <PCErr Message> ::= <Common Header>
                     ( <error-obj-list> [<Open>] ) | <error>
                     [<error-list>]

   <error-obj-list>::=<PCEP-ERROR>[<error-obj-list>]

   <error>::=[<request-id-list> | <te-id-list>]
              <error-obj-list>

   <request-id-list>::=<RP>[<request-id-list>]

   <te-id-list>::=<TE>[<te-id-list>]

   <error-list>::=<error>[<error-list>]

9.  Objects and TLV

   The PCEP objects defined in this document are compliant with the PCEP
   object format defined in [RFC5440].  The P flag and the I flag of the
   PCEP objects defined in this document MUST always be set to 0 on
   transmission and MUST be ignored on receipt since these flags are
   exclusively related to path computation requests.

9.1.  Open Object

   This document defines a new optional TLV for use in the OPEN Object.

9.1.1.  TED Capability TLV

   The TED-CAPABILITY TLV is an optional TLV for use in the OPEN Object
   for TED population via PCEP capability advertisement.  Its format 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=[TBD5]     |            Length=4           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                             Flags                           |R|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The type of the TLV is [TBD5] and it has a fixed length of 4 octets.

   The value comprises a single field - Flags (32 bits):

   o  R (remote - 1 bit): if set to 1 by a PCC, the R Flag indicates
      that the PCC allows reporting of remote TED information learned
      via other means like IGP-TE and BGP-LS; if set to 1 by a PCE, the



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      R Flag indicates that the PCE is capable of receiving remote TED
      information (from the PCC point of view).  The R Flag must be
      advertised by both a PCC and a PCE for TERpt messages to report
      remote as well as local TE information on a PCEP session.  The
      TLVs related to IGP-TE/BGP-LS identifier MUST be encoded when both
      PCEP speakers have the R Flag set.

   Unassigned bits are considered reserved.  They MUST be set to 0 on
   transmission and MUST be ignored on receipt.

   Advertisement of the TED capability implies support of local TE
   population, as well as the objects, TLVs and procedures defined in
   this document.

9.2.  TE Object

   The TE (traffic engineering) object MUST be carried within TERpt
   messages and MAY be carried within PCErr messages.  The TE object
   contains a set of fields used to specify the target TE node or link.
   It also contains a flag indicating to a PCE that the TED
   synchronization is in progress.  The TLVs used with the TE object
   correlate with the IGP-TE/BGP-LS TE encodings.

   TE Object-Class is [TBD6].

   Two Object-Type values are defined for the TE object:

   o  TE Node: TE Object-Type is 1.

   o  TE Link: TE Object-Type is 2.

   The format of the TE object body is 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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Protocol-ID  |          Flag                             |R|S|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                          TE-ID                                |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     //                         TLVs                                //
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Protocol-ID (8-bit): The field provide the source information.
   Incase PCC only provides local information (R flag is not set), it
   MUST use Protocol-ID as Direct.  The following values are defined
   (same as [I-D.ietf-idr-ls-distribution]):



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             +-------------+----------------------------------+
             | Protocol-ID | Source protocol                  |
             +-------------+----------------------------------+
             |      1      | IS-IS Level 1                    |
             |      2      | IS-IS Level 2                    |
             |      3      | OSPFv2                           |
             |      4      | Direct                           |
             |      5      | Static configuration             |
             |      6      | OSPFv3                           |
             +-------------+----------------------------------+

   Flags (32-bit):

   o  S (SYNC - 1 bit): the S Flag MUST be set to 1 on each TERpt sent
      from a PCC during TED Synchronization.  The S Flag MUST be set to
      0 in other TERpt messages sent from the PCC.

   o  R (Remove - 1 bit): On TERpt messages the R Flag indicates that
      the TE node/link has been removed from the PCC and the PCE SHOULD
      remove from its database.  Upon receiving an TE Report with the R
      Flag set to 1, the PCE SHOULD remove all state for the TE node/
      link identified by the TE Identifiers from its database.

   TE-ID(32-bit): A PCEP-specific identifier for the TE node or link.  A
   PCC creates a unique TE-ID for each TE node/link that is constant for
   the lifetime of a PCEP session.  The PCC will advertise the same TE-
   ID on all PCEP sessions it maintains at a given times.  All
   subsequent PCEP messages then address the TE node/link by the TE-ID.
   The values of 0 and 0xFFFFFFFF are reserved.

   Unassigned bits are considered reserved.  They MUST be set to 0 on
   transmission and MUST be ignored on receipt.

   TLVs that may be included in the TE Object are described in the
   following sections.

9.2.1.  Routing Universe TLV

   In case of remote TED population when existing IGP-TE/BGP-LS are also
   used, OSPF and IS-IS may run multiple routing protocol instances over
   the same link as described in [I-D.ietf-idr-ls-distribution].  See
   [RFC6822] and [RFC6549].  These instances define independent "routing
   universes".  The 64-Bit 'Identifier' field is used to identify the
   "routing universe" where the TE object belongs.  The TE objects
   representing IGP objects (nodes or links) from the same routing
   universe MUST have the same 'Identifier' value; TE objects with
   different 'Identifier' values MUST be considered to be from different
   routing universes.



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   The format of the ROUTING-UNIVERSE 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=[TBD7]         |           Length=8            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                           Identifier                          |
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Below table lists the 'Identifier' values that are defined as well-
   known in this draft (same as [I-D.ietf-idr-ls-distribution]).

                   +------------+---------------------+
                   | Identifier | Routing Universe    |
                   +------------+---------------------+
                   |     0      | L3 packet topology  |
                   |     1      | L1 optical topology |
                   +------------+---------------------+

   If this TLV is not present the default value 0 is assumed.

9.2.2.  Local TE Node Descriptors TLV

   As described in [I-D.ietf-idr-ls-distribution], each link is anchored
   by a pair of Router-IDs that are used by the underlying IGP, namely,
   48 Bit ISO System-ID for IS-IS and 32 bit Router-ID for OSPFv2 and
   OSPFv3.  Incase of additional auxiliary Router-IDs used for TE, these
   MUST also be included in the TE link attribute TLV (see
   Section 9.2.6).

   It is desirable that the Router-ID assignments inside the TE Node
   Descriptor are globally unique.  Autonomous System (AS) Number and
   PCEP-TED Identifier in order to disambiguate the Router-IDs, as
   described in [I-D.ietf-idr-ls-distribution].

   The Local TE Node Descriptors TLV contains Node Descriptors for the
   node anchoring the local end of the link.  This TLV MUST be included
   in the TE Report when during a given PCEP session a TE node/link is
   first reported to a PCE.  A PCC sends to a PCE the first TE Report
   either during State Synchronization, or when a new TE node/link is
   learned at the PCC.  The value contains one or more Node Descriptor
   Sub-TLVs, which allows specification of a flexible key for any given
   Node/Link information such that global uniqueness of the TE node/link
   is ensured.




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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=[TBD8]         |             Length            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     //              Node Descriptor Sub-TLVs (variable)            //
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The value contains one or more Node Descriptor Sub-TLVs defined in
   Section 9.2.4.

9.2.3.  Remote TE Node Descriptors TLV

   The Remote TE Node Descriptors contains Node Descriptors for the node
   anchoring the remote end of the link.  This TLV MUST be included in
   the TE Report when during a given PCEP session a TE link is first
   reported to a PCE.  A PCC sends to a PCE the first TE Report either
   during State Synchronization, or when a new TE link is learned at the
   PCC.  The length of this TLV is variable.  The value contains one or
   more Node Descriptor Sub-TLVs defined in Section 9.2.4.

      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=[TBD9]         |             Length            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     //              Node Descriptor Sub-TLVs (variable)            //
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

9.2.4.  TE Node Descriptors Sub-TLVs

   The Node Descriptor Sub-TLV type Type and lengths are listed in the
   following table:

           +--------------------+-------------------+----------+
           | Sub-TLV            | Description       |   Length |
           +--------------------+-------------------+----------+
           |        TBD10       | Autonomous System |        4 |
           |        TBD11       | BGP-LS Identifier |        4 |
           |        TBD12       | OSPF Area-ID      |        4 |
           |        TBD13       | Router-ID         | Variable |
           +--------------------+-------------------+----------+





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   The sub-TLV values in Node Descriptor TLVs are defined as follows
   (similar to [I-D.ietf-idr-ls-distribution]):

   o  Autonomous System: opaque value (32 Bit AS Number)

   o  BGP-LS Identifier: opaque value (32 Bit ID).  In conjunction with
      ASN, uniquely identifies the BGP-LS domain as described in
      [I-D.ietf-idr-ls-distribution].

   o  Area ID: It is used to identify the 32 Bit area to which the TE
      object belongs.  Area Identifier allows the different TE objects
      of the same router to be discriminated.

   o  Router ID: opaque value.  Usage is described in
      [I-D.ietf-idr-ls-distribution] for IGP Router ID.  In case only
      local TE information is transported and PCE learns TED only from
      PCEP, it contain the unique local TE IPv4 or IPv6 router ID.

   o  There can be at most one instance of each sub-TLV type present in
      any Node Descriptor.

9.2.5.  TE Link Descriptors TLV

   The TE Link Descriptors TLV contains Link Descriptors for each TE
   link.  This TLV MUST be included in the TE Report when during a given
   PCEP session a TE link is first reported to a PCE.  A PCC sends to a
   PCE the first TE Report either during State Synchronization, or when
   a new TE link is learned at the PCC.  The length of this TLV is
   variable.  The value contains one or more TE Link Descriptor Sub-TLVs

   The 'TE Link descriptor' TLVs uniquely identify a link among multiple
   parallel links between a pair of anchor routers similar to
   [I-D.ietf-idr-ls-distribution].

      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=[TBD14]        |             Length            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     //              Link Descriptor Sub-TLVs (variable)            //
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The Link Descriptor Sub-TLV type and lengths are listed in the
   following table:





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   +-----------+---------------------+---------------+-----------------+
   |  Sub-TLV  | Description         |   IS-IS TLV   | Value defined   |
   |           |                     |    /Sub-TLV   | in:             |
   +-----------+---------------------+---------------+-----------------+
   |    TBD15  | Link Local/Remote   |      22/4     | [RFC5307]/1.1   |
   |           | Identifiers         |               |                 |
   |    TBD16  | IPv4 interface      |      22/6     | [RFC5305]/3.2   |
   |           | address             |               |                 |
   |    TBD17  | IPv4 neighbor       |      22/8     | [RFC5305]/3.3   |
   |           | address             |               |                 |
   |    TBD18  | IPv6 interface      |     22/12     | [RFC6119]/4.2   |
   |           | address             |               |                 |
   |    TBD19  | IPv6 neighbor       |     22/13     | [RFC6119]/4.3   |
   |           | address             |               |                 |
   +-----------+---------------------+---------------+-----------------+

   The format and semantics of the 'value' fields in most 'Link
   Descriptor' sub-TLVs correspond to the format and semantics of value
   fields in IS-IS Extended IS Reachability sub-TLVs, defined in
   [RFC5305], [RFC5307] and [RFC6119].  Although the encodings for 'Link
   Descriptor' TLVs were originally defined for IS-IS, the TLVs can
   carry data sourced either by IS-IS or OSPF or direct.

   The information about a link present in the LSA/LSP originated by the
   local node of the link determines the set of sub-TLVs in the Link
   Descriptor of the link as described in
   [I-D.ietf-idr-ls-distribution].

9.2.6.  TE Node Attributes TLV

   This is an optional, non-transitive attribute that is used to carry
   TE node attributes.  The TE node attribute TLV may be encoded in the
   TE node Object.

      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=[TBD20]        |             Length            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     //              Node Attributes Sub-TLVs (variable)            //
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The Node Attributes Sub-TLV type and lengths are listed in the
   following table:





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   +--------------+-----------------------+----------+-----------------+
   |   Sub TLV    | Description           |   Length | Value defined   |
   |              |                       |          | in:             |
   +--------------+-----------------------+----------+-----------------+
   |     TBD21    | Node Flag Bits        |        1 | [I-D.ietf-idr-  |
   |              |                       |          | ls-distribution]|
   |              |                       |          | /3.3.1.1        |
   |     TBD22    | Opaque Node           | variable | [I-D.ietf-idr-  |
   |              | Properties            |          | ls-distribution]|
   |              |                       |          | /3.3.1.5        |
   |     TBD23    | Node Name             | variable | [I-D.ietf-idr-  |
   |              |                       |          | ls-distribution]|
   |              |                       |          | /3.3.1.3        |
   |     TBD24    | IS-IS Area Identifier | variable | [I-D.ietf-idr-  |
   |              |                       |          | ls-distribution]|
   |              |                       |          | /3.3.1.2        |
   |     TBD25    | IPv4 Router-ID of     |        4 | [RFC5305]/4.3   |
   |              | Local Node            |          |                 |
   |     TBD26    | IPv6 Router-ID of     |       16 | [RFC6119]/4.1   |
   |              | Local Node            |          |                 |
   +--------------+-----------------------+----------+-----------------+

9.2.7.  TE Link Attributes TLV

   TE Link attribute TLV may be encoded in the TE Link Object.  The
   format and semantics of the 'value' fields in some 'Link Attribute'
   sub-TLVs correspond to the format and semantics of value fields in
   IS-IS Extended IS Reachability sub-TLVs, defined in [RFC5305],
   [RFC5307] and [I-D.ietf-idr-ls-distribution].  Although the encodings
   for 'Link Attribute' TLVs were originally defined for IS-IS, the TLVs
   can carry data sourced either by IS-IS or OSPF or direct.

      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=[TBD27]        |             Length            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     //              Link Attributes Sub-TLVs (variable)            //
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The following 'Link Attribute' sub-TLVs are are valid :








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   +-----------+---------------------+--------------+------------------+
   |  Sub-TLV  | Description         |  IS-IS TLV   | Defined in:      |
   |           |                     |   /Sub-TLV   |                  |
   |           |                     |  BGP-LS TLV  |                  |
   +-----------+---------------------+--------------+------------------+
   |    TBD28  | IPv4 Router-ID of   |   134/---    | [RFC5305]/4.3    |
   |           | Local Node          |              |                  |
   |    TBD29  | IPv6 Router-ID of   |   140/---    | [RFC6119]/4.1    |
   |           | Local Node          |              |                  |
   |    TBD30  | IPv4 Router-ID of   |   134/---    | [RFC5305]/4.3    |
   |           | Remote Node         |              |                  |
   |    TBD31  | IPv6 Router-ID of   |   140/---    | [RFC6119]/4.1    |
   |           | Remote Node         |              |                  |
   |    TBD32  | Link Local/Remote   |     22/4     | [RFC5307]/1.1    |
   |           | Identifiers         |              |                  |
   |    TBD33  | Administrative      |     22/3     | [RFC5305]/3.1    |
   |           | group (color)       |              |                  |
   |    TBD34  | Maximum link        |     22/9     | [RFC5305]/3.3    |
   |           | bandwidth           |              |                  |
   |    TBD35  | Max. reservable     |    22/10     | [RFC5305]/3.5    |
   |           | link bandwidth      |              |                  |
   |    TBD36  | Unreserved          |    22/11     | [RFC5305]/3.6    |
   |           | bandwidth           |              |                  |
   |    TBD37  | TE Default Metric   |    22/18     | [I-D.ietf-idr-   |
   |           |                     |              | ls-distribution] |
   |           |                     |              | /3.3.2.3         |
   |    TBD38  | Link Protection     |    22/20     | [RFC5307]/1.2    |
   |           | Type                |              |                  |
   |    TBD39  | MPLS Protocol Mask  |     1094     | [I-D.ietf-idr-   |
   |           |                     |              | ls-distribution] |
   |           |                     |              | /3.3.2.2         |
   |    TBD40  | IGP Metric          |     1095     | [I-D.ietf-idr-   |
   |           |                     |              | ls-distribution] |
   |           |                     |              | /3.3.2.4         |
   |    TBD41  | Shared Risk Link    |     1096     | [I-D.ietf-idr-   |
   |           | Group               |              | ls-distribution] |
   |           |                     |              | /3.3.2.5         |
   |    TBD42  | Opaque link         |     1097     | [I-D.ietf-idr-   |
   |           | attributes          |              | ls-distribution] |
   |           |                     |              | /3.3.2.6         |
   |    TBD43  | Link Name attribute |     1098     | [I-D.ietf-idr-   |
   |           |                     |              | ls-distribution] |
   |           |                     |              | /3.3.2.7         |
   +-----------+---------------------+--------------+------------------+







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10.  Other Considerations

10.1.  Inter-AS Links

   The main source of TE information is the IGP, which is not active on
   inter-AS links.  In some cases, the IGP may have information of
   inter-AS links ([RFC5392], [RFC5316]).  In other cases, an
   implementation SHOULD provide a means to inject inter-AS links into
   PCEP.  The exact mechanism used to provision the inter-AS links is
   outside the scope of this document.

11.  Security Considerations

   TBD.

12.  Manageability Considerations

12.1.  Control of Function and Policy

   TBD.

12.2.  Information and Data Models

   TBD.

12.3.  Liveness Detection and Monitoring

   TBD.

12.4.  Verify Correct Operations

   TBD.

12.5.  Requirements On Other Protocols

   TBD.

12.6.  Impact On Network Operations

   TBD.

13.  IANA Considerations









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14.  Acknowledgments

   This document borrows some of the structure and text from the
   [I-D.ietf-pce-stateful-pce].

15.  References

15.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5440]  Vasseur, JP. and JL. Le Roux, "Path Computation Element
              (PCE) Communication Protocol (PCEP)", RFC 5440, March
              2009.

15.2.  Informative References

   [RFC3630]  Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
              (TE) Extensions to OSPF Version 2", RFC 3630, September
              2003.

   [RFC4203]  Kompella, K. and Y. Rekhter, "OSPF Extensions in Support
              of Generalized Multi-Protocol Label Switching (GMPLS)",
              RFC 4203, October 2005.

   [RFC4655]  Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
              Element (PCE)-Based Architecture", RFC 4655, August 2006.

   [RFC5305]  Li, T. and H. Smit, "IS-IS Extensions for Traffic
              Engineering", RFC 5305, October 2008.

   [RFC5307]  Kompella, K. and Y. Rekhter, "IS-IS Extensions in Support
              of Generalized Multi-Protocol Label Switching (GMPLS)",
              RFC 5307, October 2008.

   [RFC5316]  Chen, M., Zhang, R., and X. Duan, "ISIS Extensions in
              Support of Inter-Autonomous System (AS) MPLS and GMPLS
              Traffic Engineering", RFC 5316, December 2008.

   [RFC5392]  Chen, M., Zhang, R., and X. Duan, "OSPF Extensions in
              Support of Inter-Autonomous System (AS) MPLS and GMPLS
              Traffic Engineering", RFC 5392, January 2009.

   [RFC6119]  Harrison, J., Berger, J., and M. Bartlett, "IPv6 Traffic
              Engineering in IS-IS", RFC 6119, February 2011.





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   [RFC6549]  Lindem, A., Roy, A., and S. Mirtorabi, "OSPFv2 Multi-
              Instance Extensions", RFC 6549, March 2012.

   [RFC6822]  Previdi, S., Ginsberg, L., Shand, M., Roy, A., and D.
              Ward, "IS-IS Multi-Instance", RFC 6822, December 2012.

   [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-10 (work in progress), October 2014.

   [I-D.ietf-idr-ls-distribution]
              Gredler, H., Medved, J., Previdi, S., Farrel, A., and S.
              Ray, "North-Bound Distribution of Link-State and TE
              Information using BGP", draft-ietf-idr-ls-distribution-06
              (work in progress), September 2014.

   [I-D.lee-pce-transporting-te-data]
              Lee, Y. and z. zhenghaomian@huawei.com, "PCE in Support of
              Transporting Traffic Engineering Data", draft-lee-pce-
              transporting-te-data-01 (work in progress), October 2014.






























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Appendix A.  Contributor Addresses

   Udayasree Palle
   Huawei Technologies
   Leela Palace
   Bangalore, Karnataka  560008
   India

   EMail: udayasree.palle@huawei.com


Authors' Addresses

   Dhruv Dhody
   Huawei Technologies
   Leela Palace
   Bangalore, Karnataka  560008
   India

   EMail: dhruv.ietf@gmail.com


   Young Lee
   Huawei Technologies
   5340 Legacy Drive, Building 3
   Plano, TX  75023
   USA

   EMail: leeyoung@huawei.com


   Daniele Ceccarelli
   Ericsson
   Torshamnsgatan,48
   Stockholm
   Sweden

   EMail: daniele.ceccarelli@ericsson.com













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