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Versions: (draft-lee-pce-wson-rwa-ext) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17

Network Working Group                                       Y. Lee, Ed.
Internet Draft                                      Huawei Technologies

Intended status: Standard Track                        R. Casellas, Ed.
Expires: July 14, 2019                                             CTTC





                                                       January 14, 2019


PCEP Extension for WSON Routing and Wavelength Assignment


                      draft-ietf-pce-wson-rwa-ext-11


Abstract

   This document provides the Path Computation Element communication
   Protocol (PCEP) extensions for the support of Routing and Wavelength
   Assignment (RWA) in Wavelength Switched Optical Networks (WSON).
   Path provisioning in WSONs requires a routing and wavelength
   assignment (RWA) process.  From a path computation perspective,
   wavelength assignment is the process of determining which wavelength
   can be used on each hop of a path and forms an additional routing
   constraint to optical path computation.

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with
   the provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
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   Drafts.

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   reference material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt




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   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on July 14, 2019.

Copyright Notice

   Copyright (c) 2019 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. Terminology....................................................3
   2. Requirements Language..........................................3
   3. Introduction...................................................3
   4. Encoding of a RWA Path Request.................................6
      4.1. Wavelength Assignment (WA) Object.........................6
      4.2. Wavelength Selection TLV..................................8
      4.3. Wavelength Restriction Constraint TLV.....................8
         4.3.1. Link Identifier Field...............................11
         4.3.2. Wavelength Restriction Field........................12
      4.4. Signal processing capability restrictions................13
         4.4.1. Signal Processing Exclusion XRO Sub-Object..........14
         4.4.2. IRO sub-object: signal processing inclusion.........15
   5. Encoding of a RWA Path Reply..................................15
      5.1. Error Indicator..........................................17
      5.2. NO-PATH Indicator........................................17
   6. Manageability Considerations..................................18
      6.1. Control of Function and Policy...........................18
      6.2. Liveness Detection and Monitoring........................18
      6.3. Verifying Correct Operation..............................18
      6.4. Requirements on Other Protocols and Functional Components19
      6.5. Impact on Network Operation..............................19
   7. Security Considerations.......................................19



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   8. IANA Considerations...........................................19
      8.1. New PCEP Object..........................................19
      8.2. New PCEP TLV: Wavelength Selection TLV...................20
      8.3. New PCEP TLV: Wavelength Restriction Constraint TLV......20
      8.4. New PCEP TLV: Wavelength Allocation TLV..................20
      8.5. New PCEP TLV: Optical Interface Class List TLV...........21
      8.6. New PCEP TLV: Client Signal TLV..........................21
      8.7. New No-Path Reasons......................................21
      8.8. New Error-Types and Error-Values.........................22
   9. Acknowledgments...............................................22
   10. References...................................................22
      10.1. Normative References....................................22
      10.2. Informative References..................................23
   11. Contributors.................................................24
   Authors' Addresses...............................................25



1. Terminology

   This document uses the terminology defined in [RFC4655], and
   [RFC5440].

2. 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.

3. Introduction

   [RFC5440] specifies the Path Computation Element (PCE) Communication
   Protocol (PCEP) for communications between a Path Computation Client
   (PCC) and a PCE, or between two PCEs.  Such interactions include
   path computation requests and path computation replies as well as
   notifications of specific states related to the use of a PCE in the
   context of Multiprotocol Label Switching (MPLS) and Generalized MPLS
   (GMPLS) Traffic Engineering.

   A PCC is said to be any network component that makes such a request
   and may be, for instance, an Optical Switching Element within a
   Wavelength Division Multiplexing (WDM) network.  The PCE, itself,
   can be located anywhere within the network, and may be within an
   optical switching element, a Network Management System (NMS) or



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   Operational Support System (OSS), or may be an independent network
   server.

   This document provides the PCEP extensions for the support of
   Routing and Wavelength Assignment (RWA) in Wavelength Switched
   Optical Networks (WSON) based on the requirements specified in
   [RFC6163] and [RFC7449].

   WSON refers to WDM based optical networks in which switching is
   performed selectively based on the wavelength of an optical signal.
   The devices used in WSONs that are able to switch signals based on
   signal wavelength are known as Lambda Switch Capable (LSC). WSONs
   can be transparent or translucent. A transparent optical network is
   made up of optical devices that can switch but not convert from one
   wavelength to another, all within the optical domain. On the other
   hand, translucent networks include 3R regenerators that are sparsely
   placed. The main function of the 3R regenerators is to convert one
   optical wavelength to another.

   A Lambda Switch Capable (LSC) Label Switched Path (LSP) may span one
   or several transparent segments, which are delimited by 3R
   regenerators (Re-amplification, Re-shaping, Re-timing) typically
   with electronic regenerator and optional wavelength conversion. Each
   transparent segment or path in WSON is referred to as an optical
   path. An optical path may span multiple fiber links and the path
   should be assigned the same wavelength for each link. In such case,
   the optical path is said to satisfy the wavelength-continuity
   constraint. Figure 1 illustrates the relationship between a LSC LSP
   and transparent segments (optical paths).

   +---+       +-----+       +-----+      +-----+         +-----+
   |   |I1     |     |       |     |      |     |       I2|     |
   |   |o------|     |-------[(3R) ]------|     |--------o|     |
   |   |       |     |       |     |      |     |         |     |
   +---+       +-----+       +-----+      +-----+         +-----+
       (X  LSC)     (LSC  LSC)    (LSC  LSC)     (LSC  X)
        <------->   <------->       <----->     <------->
        <-----------------------><---------------------->
         Transparent Segment         Transparent Segment
       <------------------------------------------------->
                              LSC LSP


   Figure 1 Illustration of a LSC LSP and transparent segments





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   Note that two optical paths within a WSON LSP do not need to operate
   on the same wavelength (due to the wavelength conversion
   capabilities). Two optical paths that share a common fiber link
   cannot be assigned the same wavelength; Otherwise, the two signals
   would interfere with each other. Note that advanced additional
   multiplexing techniques such as polarization based multiplexing are
   not addressed in this document since the physical layer aspects are
   not currently standardized. Therefore, assigning the proper
   wavelength on a path is an essential requirement in the optical path
   computation process.

   When a switching node has the ability to perform wavelength
   conversion, the wavelength-continuity constraint can be relaxed, and
   a LSC Label Switched Path (LSP) may use different wavelengths on
   different links along its route from origin to destination. It is,
   however, to be noted that wavelength converters may be limited due
   to their relatively high cost, while the number of WDM channels that
   can be supported in a fiber is also limited. As a WSON can be
   composed of network nodes that cannot perform wavelength conversion,
   nodes with limited wavelength conversion, and nodes with full
   wavelength conversion abilities, wavelength assignment is an
   additional routing constraint to be considered in all optical path
   computation.

   For example (see Figure 1), within a translucent WSON, a LSC LSP may
   be established between interfaces I1 and I2, spanning 2 transparent
   segments (optical paths) where the wavelength continuity constraint
   applies (i.e. the same unique wavelength must be assigned to the LSP
   at each TE link of the segment). If the LSC LSP induced a Forwarding
   Adjacency / TE link, the switching capabilities of the TE link would
   be (X X) where X refers to the switching capability of I1 and I2.
   For example, X can be PSC, TDM, etc.

   This document aligns with GMPLS extensions for PCEP [PCEP-GMPLS] for
   generic properties such as label, label-set and label assignment
   noting that wavelength is a type of label. Wavelength restrictions
   and constraints are also formulated in terms of labels per
   [RFC7579].

   The optical modulation properties, which are also referred to as
   signal compatibility, are already considered in signaling in
   [RFC7581] and [RFC7688]. In order to improve the signal quality and
   limit some optical effects several advanced modulation processing
   capabilities are used. These modulation capabilities contribute not
   only to optical signal quality checks but also constrain the
   selection of sender and receiver, as they should have matching
   signal processing capabilities. This document includes signal


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   compatibility constraints as part of RWA path computation. That is,
   the signal processing capabilities (e.g., modulation and FEC)
   indicated by means of optical interface class (OIC) must be
   compatible between the sender and the receiver of the optical path
   across all optical elements.

   This document, however, does not address optical impairments as part
   of RWA path computation.

4. Encoding of a RWA Path Request

   Figure 2 shows one typical PCE based implementation, which is
   referred to as the Combined Process (R&WA). With this architecture,
   the two processes of routing and wavelength assignment are accessed
   via a single PCE. This architecture is the base architecture
   specified in [RFC6163] and the PCEP extensions that are specified in
   this document are based on this architecture.

                          +----------------------------+
            +-----+       |     +-------+     +--+     |
            |     |       |     |Routing|     |WA|     |
            | PCC |<----->|     +-------+     +--+     |
            |     |       |                            |
            +-----+       |             PCE            |
                          +----------------------------+


               Figure 2 Combined Process (R&WA) architecture



4.1. Wavelength Assignment (WA) Object

   Wavelength allocation can be performed by the PCE by different
   means:

   (a) By means of Explicit Label Control [RFC3471] where the PCE
   allocates which label to use for each interface/node along the path.
   The allocated labels MAY appear after an interface route subobject.

   (b) By means of a Label Set where the PCE provides a range of
   potential labels to allocate by each node along the path.

   Option (b) allows distributed label allocation (performed during
   signaling) to complete wavelength assignment.




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   Additionally, given a range of potential labels to allocate, the
   request SHOULD convey the heuristic / mechanism to the allocation.

   The format of a PCReq message after incorporating the Wavelength
   Assignment (WA) object is as follows:

   <PCReq Message> ::= <Common Header>

                          [<svec-list>]

                          <request-list>

      Where:

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

         <request>::= <RP>

                      <ENDPOINTS>

                      <WA>

                      [other optional objects...]

   If the WA object is present in the request, it MUST be encoded after
   the ENDPOINTS object as defined in [PCEP-GMPLS]. Orderings with
   respect to the other following objects are irrelevant.

   The format of the WA 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Reserved             |           Flags             |M|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Wavelength Selection TLV                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             Wavelength Restriction Constraint TLV             |
   .                                                               .
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                            Figure 3 WA Object

   o  Reserved (16 bits): Reserved for future use and SHOULD be zeroed.


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   o  Flags (16 bits)

   One flag bit is allocated as follows:

     . M (Mode - 1 bit): M bit is used to indicate the mode of
        wavelength assignment. When M bit is set to 1, this indicates
        that the label assigned by the PCE must be explicit. That is,
        the selected way to convey the allocated wavelength is by means
        of Explicit Label Control for each hop of a computed LSP.
        Otherwise (M bit is set to 0), the label assigned by the PCE
        need not be explicit (i.e., it can be suggested in the form of
        label set objects in the corresponding response, to allow
        distributed WA. If M is 0, the PCE MUST return a Label Set
        Field as described in Section 2.6 of [RFC7579] in the response.
        See Section 5 of this document for the encoding discussion of a
        Label Set Field in a PCRep message.

     All unused flags SHOULD be zeroed.

     . Wavelength Selection TLV (32 bits): See Section 4.2 for
        details.

     . Wavelength Restriction Constraint TLV (Variable): See Section
        4.3 for details.

4.2. Wavelength Selection TLV

   The Wavelength Selection TLV is used to indicate the wavelength
   selection constraint in regard to the order of wavelength assignment
   to be returned by the PCE. This TLV is only applied when M bit is
   set in the WA Object specified in Section 4.1. This TLV MUST NOT be
   used when the M bit is cleared.

   The encoding of this TLV is specified as the Wavelength Selection
   Sub-TLV in Section 4.2.2 of [RFC7689].



4.3. Wavelength Restriction Constraint TLV

   For any request that contains a wavelength assignment, the requester
   (PCC) MUST be able to specify a restriction on the wavelengths to be
   used. This restriction is to be interpreted by the PCE as a
   constraint on the tuning ability of the origination laser
   transmitter or on any other maintenance related constraints. Note
   that if the LSP LSC spans different segments, the PCE MUST have
   mechanisms to know the tunability restrictions of the involved


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   wavelength converters / regenerators, e.g. by means of the TED
   either via IGP or NMS. Even if the PCE knows the tunability of the
   transmitter, the PCC MUST be able to apply additional constraints to
   the request.

   The format of the Wavelength Restriction Constraint TLV is as
   follows:

   <Wavelength Restriction Constraint> ::=

                  <Action> <Count> <Reserved>

                  (<Link Identifiers> <Wavelength Restriction>)...

   Where

   <Link Identifiers> ::= <Link Identifier> [<Link Identifiers>]

   See Section 4.3.1. for the encoding of the Link Identifiers Field.



   The Wavelength Restriction Constraint TLV type is TBD3 (See Section
   8.3). This TLV MAY appear more than once to be able to specify
   multiple restrictions.

   The TLV data is defined as follows:



   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Action          |    Count      |          Reserved           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Link Identifiers                          |
   |                          . . .                                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                Wavelength Restriction Field                   |
   //                        . . . .                              //
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

          Figure 4 Wavelength Restriction Constraint TLV Encoding




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   o  Action (8 bits):


      .  0 - Inclusive List indicates that one or more link identifiers
         are included in the Link Set. Each identifies a separate link
         that is part of the set.

      .  1 - Inclusive Range indicates that the Link Set defines a
         range of links.  It contains two link identifiers. The first
         identifier indicates the start of the range (inclusive). The
         second identifier indicates the end of the range (inclusive).
         All links with numeric values between the bounds are
         considered to be part of the set. A value of zero in either
         position indicates that there is no bound on the corresponding
         portion of the range.


   Note that "interfaces" are assumed to be bidirectional.


   o  Count (8 bits): The number of the link identifiers

   Note that a PCC MAY add a Wavelength restriction that applies to all
   links by setting the Count field to zero and specifying just a set
   of wavelengths.

   Note that all link identifiers in the same list must be of the same
   type.

   o  Reserved (16 bits): Reserved for future use and SHOULD be zeroed.


   o  Link Identifiers: Identifies each link ID for which restriction
   is applied. The length is dependent on the link format and the Count
   field. See Section 4.3.1. for Link Identifier encoding and Section
   4.3.2. for the Wavelength Restriction Field encoding, respectively.

   Various encoding errors are possible with this TLV (e.g., not
   exactly two link identifiers with the range case, unknown identifier
   types, no matching link for a given identifier, etc.). To indicate
   errors associated with this type, a new Error-Type (TBD8) and an
   Error-value (Error-value=3) MUST be defined so that the PCE MUST
   send a PCErr message with a PCEP-ERROR Object. See Section 5.1 for
   the details.


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4.3.1. Link Identifier Field

   The link identifier field can be an IPv4 [RFC3630], IPv6 [RFC5329]
   or unnumbered interface ID [RFC4203].

   <Link Identifier> ::=

               <IPV4 Address> | <IPV6 Address> | <Unnumbered IF ID>

   The encoding of each case is as follows:


      IPv4 prefix sub-TLV

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Type = 1     |    Reserved  (16 bits)                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | IPv4 address (4 bytes)                                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      IPv6 prefix Sub-TLV

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Type = 2     |    Reserved  (16 bits)                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | IPv6 address (16 bytes)                                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | IPv6 address (continued)                                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | IPv6 address (continued)                                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | IPv6 address (continued)                                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Unnumbered Interface ID Sub-TLV

   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



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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Type = 3     |    Reserved (16 bits)                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        TE Node ID (32 bits)                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Interface ID (32 bits)                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Type (8 bits): It indicates the type of the link identifier.

      Reserved (16 bits): Reserved for future use and SHOULD be zeroed.


4.3.2. Wavelength Restriction Field

   The Wavelength Restriction Field of the wavelength restriction TLV
   is encoded as a Label Set field as specified in Section 2.6 in
   [RFC7579] with base label encoded as a 32 bit LSC label, defined in
   [RFC6205].  See [RFC6205] for a description of Grid, C.S, Identifier
   and n, as well as [RFC7579] for the details of each action.

  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

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | Action|    Num Labels         |          Length               |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |Grid | C.S   |    Identifier   |              n                |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |     Additional fields as necessary per action                 |
  |                                                               |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Action (4 bits):

            0  - Inclusive List

            1  - Exclusive List

            2  - Inclusive Range

            3  - Exclusive Range


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            4  - Bitmap Set

   Num Labels (12 bits): It is generally the number of labels. It has a
   specific meaning depending on the action value.

   Length (16 bits): It is the length in bytes of the entire label set
   field.

   See Sections 2.6.1 - 2.6.3 of [RFC7579] for details on additional
   field discussion for each action.



4.4. Signal processing capability restrictions

   Path computation for WSON includes checking of signal processing
   capabilities at each interface against requested capability; this
   requirement MAY be implemented by the IGP.  Moreover, a PCC should
   be able to indicate additional restrictions to signal processing
   compatibility, either on the endpoint or any given link.

   The supported signal processing capabilities are those described in
   [RFC7446]:

      .  Optical Interface Class List

      .  Bit Rate

      .  Client Signal

   The Bit Rate restriction is already expressed in [PCEP-GMPLS] in the
   BANDWIDTH object.

   In order to support the Optical Interface Class information and the
   Client Signal information new TLVs are introduced as endpoint-
   restriction in the END-POINTS type Generalized endpoint:

      .  Client Signal TLV

      .  Optical Interface Class List TLV

   The END-POINTS type generalized endpoint is extended as follows:

   <endpoint-restrictions> ::= <LABEL-REQUEST>


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                               <Wavelength Restriction Constraint>

                               [<signal-compatibility-restriction>...]



Where

   signal-compatibility-restriction ::=

                    <Optical Interface Class List> <Client Signal>

   The encoding for the Optical Interface Class List is described in
   Section 4.1 of [RFC7581].

   The encoding for the Client Signal Information is described in
   Section 4.2 of [RFC7581].



4.4.1. Signal Processing Exclusion XRO Sub-Object

   The PCC/PCE should be able to exclude particular types of signal
   processing along the path in order to handle client restriction or
   multi-domain path computation. [RFC5440] defines how Exclude Route
   Object (XRO) sub-object is used. In this draft, we add a new XRO
   sub-object, signal processing sub-object.

   In order to support the exclusion a new XRO sub-object is defined:
   the signal processing exclusion:

   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |X|  Type = X   |     Length    |   Reserved    | Attribute     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 sub-sub objects                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


               Figure 5 Signaling Processing XRO Sub-Object

   Refer to [RFC5521] for the definition of X, Type, Length and
   Attribute.



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   Reserved bits (8 bits) are for future use and SHOULD be zeroed.

   The Attribute field (8 bits) indicates how the exclusion sub-object
   is to be interpreted. The Attribute can only be 0 (Interface) or 1
   (Node).

   The permitted sub-sub objects are the Optical Interface Class List
   and the Client Signal information whose encodings are described in
   Section 4.1 and Section 4.2 of [RFC7581], respectively.



4.4.2. IRO sub-object: signal processing inclusion

   Similar to the XRO sub-object, the PCC/PCE should be able to include
   particular types of signal processing along the path in order to
   handle client restriction or multi-domain path computation.
   [RFC5440] defines how Include Route Object (IRO) sub-object is used.
   In this draft, we add a new IRO sub-object, signal processing sub-
   object.

   This is supported by adding the sub-object "WSON Processing Hop
   Attribute TLV" defined for ERO in Section 4.2 [RFC7689] to the PCEP
   IRO object [RFC5440].



5. Encoding of a RWA Path Reply

   This section provides the encoding of a RWA Path Reply for
   wavelength allocation request as discussed in Section 4. Recall that
   wavelength allocation can be performed by the PCE by different
   means:

   (a)  By means of Explicit Label Control (ELC) where the PCE
        allocates which label to use for each interface/node along the
        path.
   (b)  By means of a Label Set where the PCE provides a range of
        potential labels to allocate by each node along the path.

   Option (b) allows distributed label allocation (performed during
   signaling) to complete wavelength allocation.

   The Wavelength Allocation TLV type is TBD4 (See Section 8.4). The
   TLV data is defined as follows:




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   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              Type             |        Length               |M|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Link Identifier                           |
   |                          . . .                                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Allocated Wavelength(s)                    |
   //                        . . . .                              //
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 6 Wavelength Allocation TLV Encoding


   o  Type (16 bits): The type of the TLV.

   o  Length (15 bits): The length of the TLV including the Type and
                        Length fields.

   o  M (Mode): 1 bit


      -  0 indicates the allocation is under Explicit Label Control.

      -  1 indicates the allocation is expressed in Label Sets.


   Note that all link identifiers in the same list must be of the same
   type.


   o  Link Identifier: Identifies the interface to which assignment
   wavelength(s) is applied. See Section 4.3.1. for Link Identifier
   encoding.

   o  Allocated Wavelength(s): Indicates the allocated wavelength(s) to
   be associated with the Link Identifier. See Section 4.3.2 for
   encoding details.

   This TLV is encoded as an attributes TLV, per [RFC5420], which is
   carried in the ERO LSP Attribute Subobjects per [RFC7570].



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5.1. Error Indicator

   To indicate errors associated with the RWA request, a new Error Type
   (TBD8) and subsequent error-values are defined as follows for
   inclusion in the PCEP-ERROR Object:

   A new Error-Type (TBD8) and subsequent error-values are defined as
   follows:

      .  Error-Type=TBD8; Error-value=1: if a PCE receives a RWA
         request and the PCE is not capable of processing the request
         due to insufficient memory, the PCE MUST send a PCErr message
         with a PCEP-ERROR Object (Error-Type=TBD8) and an Error-
         value(Error-value=1).  The PCE stops processing the request.
         The corresponding RWA request MUST be cancelled at the PCC.

      .  Error-Type=TBD8; Error-value=2: if a PCE receives a RWA
         request and the PCE is not capable of RWA computation, the PCE
         MUST send a PCErr message with a PCEP-ERROR Object (Error-
         Type=TBD8) and an Error-value (Error-value=2). The PCE stops
         processing the request.  The corresponding RWA computation
         MUST be cancelled at the PCC.

      .  Error-Type=TBD8; Error-value=3: if a PCE receives a RWA
         request and there are syntactical encoding errors (e.g., not
         exactly two link identifiers with the range case, unknown
         identifier types, no matching link for a given identifier,
         etc.), the PCE MUST send a PCErr message with a PCEP-ERROR
         Object (Error-Type=TBD8) and an Error-value (Error-value=3).




5.2. NO-PATH Indicator


   To communicate the reason(s) for not being able to find RWA for the
   path request, the NO-PATH object can be used in the corresponding
   response.  The format of the NO-PATH object body is defined in
   [RFC5440].  The object may contain a NO-PATH-VECTOR TLV to provide
   additional information about why a path computation has failed.

   One new bit flag is defined to be carried in the Flags field in the
   NO-PATH-VECTOR TLV carried in the NO-PATH Object.



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      .  Bit TBD7: When set, the PCE indicates no feasible route was
         found that meets all the constraints (e.g., wavelength
         restriction, signal compatibility, etc.) associated with RWA.



6. Manageability Considerations

   Manageability of WSON Routing and Wavelength Assignment (RWA) with
   PCE must address the following considerations:

6.1. Control of Function and Policy

   In addition to the parameters already listed in Section 8.1 of
   [RFC5440], a PCEP implementation SHOULD allow configuration of the
   following PCEP session parameters on a PCC:

      .  The ability to send a WSON RWA request.

   In addition to the parameters already listed in Section 8.1 of
   [RFC5440], a PCEP implementation SHOULD allow configuration of the
   following PCEP session parameters on a PCE:

      .  The support for WSON RWA.

      .  A set of WSON RWA specific policies (authorized sender,
         request rate limiter, etc).


   These parameters may be configured as default parameters for any
   PCEP session the PCEP speaker participates in, or may apply to a
   specific session with a given PCEP peer or a specific group of
   sessions with a specific group of PCEP peers.


6.2. Liveness Detection and Monitoring

   Mechanisms defined in this document do not imply any new liveness
   detection and monitoring requirements in addition to those already
   listed in section 8.3 of [RFC5440].


6.3. Verifying Correct Operation

   Mechanisms defined in this document do not imply any new
   verification requirements in addition to those already listed in
   section 8.4 of [RFC5440]


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6.4. Requirements on Other Protocols and Functional Components

   The PCEP Link-State mechanism [PCEP-LS] may be used to advertise
   WSON RWA path computation capabilities to PCCs.


6.5. Impact on Network Operation

   Mechanisms defined in this document do not imply any new network
   operation requirements in addition to those already listed in
   section 8.6 of [RFC5440].

7. Security Considerations

   The security considerations discussed in [RFC5440] are relevant for
   this document, this document does not introduce any new security
   issues. If an operator wishes to keep private the information
   distributed by WSON, PCEPS [RFC8253] SHOULD be used.

8. IANA Considerations

   IANA maintains a registry of PCEP parameters. IANA has made
   allocations from the sub-registries as described in the following
   sections.

8.1. New PCEP Object

   As described in Section 4.1, a new PCEP Object is defined to carry
   wavelength assignment related constraints. IANA is to allocate the
   following from "PCEP Objects" sub-registry
   (http://www.iana.org/assignments/pcep/pcep.xhtml#pcep-objects):




   Object Class   Name  Object                     Reference
   Value                Type
   ---------------------------------------------------------


   TBD1           WA    1: Wavelength-Assignment   [This.I-D]





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8.2. New PCEP TLV: Wavelength Selection TLV

   As described in Sections 4.2, a new PCEP TLV is defined to indicate
   wavelength selection constraints. IANA is to allocate this new TLV
   from the "PCEP TLV Type Indicators" subregistry
   (http://www.iana.org/assignments/pcep/pcep.xhtml#pcep-tlv-type-
   indicators).

   Value             Description                Reference
   ---------------------------------------------------------
   TBD2              Wavelength Selection       [This.I-D]



8.3. New PCEP TLV: Wavelength Restriction Constraint TLV

   As described in Sections 4.3, a new PCEP TLV is defined to indicate
   wavelength restriction constraints. IANA is to allocate this new TLV
   from the "PCEP TLV Type Indicators" subregistry
   (http://www.iana.org/assignments/pcep/pcep.xhtml#pcep-tlv-type-
   indicators).

   Value             Description                Reference
   ---------------------------------------------------------
   TBD3              Wavelength Restriction     [This.I-D]
                     Constraint


8.4. New PCEP TLV: Wavelength Allocation TLV

   As described in Section 5, a new PCEP TLV is defined to indicate the
   allocation of wavelength(s) by the PCE in response to a request by
   the PCC. IANA is to allocate this new TLV from the "PCEP TLV Type
   Indicators" subregistry
   (http://www.iana.org/assignments/pcep/pcep.xhtml#pcep-tlv-type-
   indicators).

   Value             Description                Reference
   ---------------------------------------------------------
   TBD4              Wavelength Allocation      [This.I-D]



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8.5. New PCEP TLV: Optical Interface Class List TLV

   As described in Section 4.3, a new PCEP TLV is defined to indicate
   the optical interface class list. IANA is to allocate this new TLV
   from the "PCEP TLV Type Indicators" subregistry
   (http://www.iana.org/assignments/pcep/pcep.xhtml#pcep-tlv-type-
   indicators).


   Value             Description                Reference
   ---------------------------------------------------------
   TBD5              Optical Interface          [This.I-D]
                     Class List

8.6. New PCEP TLV: Client Signal TLV

   As described in Section 4.3, a new PCEP TLV is defined to indicate
   the client signal information. IANA is to allocate this new TLV from
   the "PCEP TLV Type Indicators" subregistry
   (http://www.iana.org/assignments/pcep/pcep.xhtml#pcep-tlv-type-
   indicators).


   Value             Description                Reference
   ---------------------------------------------------------
   TBD6              Client Signal Information  [This.I-D]



8.7. New No-Path Reasons

   As described in Section 5.2., a new bit flag are defined to be
   carried in the Flags field in the NO-PATH-VECTOR TLV carried in the
   NO-PATH Object. This flag, when set, indicates that no feasible
   route was found that meets all the RWA constraints (e.g., wavelength
   restriction, signal compatibility, etc.) associated with a RWA path
   computation request.

   IANA is to allocate this new bit flag from the "PCEP NO-PATH-VECTOR
   TLV Flag Field" subregistry



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   (http://www.iana.org/assignments/pcep/pcep.xhtml#no-path-vector-
   tlv).

   Bit         Description                Reference
   -----------------------------------------------------
   TBD7        No RWA constraints met     [This.I-D]

8.8. New Error-Types and Error-Values

   As described in Section 5.1, new PCEP error codes are defined for
   WSON RWA errors. IANA is to allocate from the ""PCEP-ERROR Object
   Error Types and Values" sub-registry
   (http://www.iana.org/assignments/pcep/pcep.xhtml#pcep-error-object).



   Error-      Meaning           Error-Value       Reference
   Type
   ---------------------------------------------------------------


   TBD8        WSON RWA Error    1: Insufficient      [This.I-D]
                                    Memory

                                 2: RWA computation   {This.I-D]
                                    Not supported



9. Acknowledgments

   The authors would like to thank Adrian Farrel for many helpful
   comments that greatly improved the contents of this draft.

   This document was prepared using 2-Word-v2.0.template.dot.



10. References

10.1. Normative References

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



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

   [RFC5329] A. Lindem, Ed., "Traffic Engineering Extensions to OSPF
             Version 3", RFC 5329, September 2008.

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

   [RFC6205] Tomohiro, O. and D. Li, "Generalized Labels for Lambda-
             Switching Capable Label Switching Routers", RFC 6205,
             January, 2011.

   [RFC7570] C. Margaria, et al., "Label Switched Path (LSP) Attribute
             in the Explicit Route Object (ERO)", RFC 7570, July 2015.

   [RFC7579] G. Bernstein and Y. Lee, "General Network Element
             Constraint Encoding for GMPLS Controlled Networks", RFC
             7579, June 2015.

   [RFC7581] G. Bernstein and Y. Lee, "Routing and Wavelength
             Assignment Information Encoding for Wavelength Switched
             Optical Networks", RFC7581, June 2015.

   [RFC7689] Bernstein et al., "Signaling Extensions for Wavelength
             Switched Optical Networks", RFC 7689, November 2015.

   [RFC7688] Y. Lee, and G. Bernstein, "OSPF Enhancement for Signal and
             Network Element Compatibility for Wavelength Switched
             Optical Networks", RFC 7688, November 2015.

   [RFC8174] B. Leiba, "Ambiguity of Uppercase vs Lowercase in RFC 2119
             Key Words", RFC 8174, May 2017.

   [PCEP-GMPLS] C. Margaria, et al., "PCEP extensions for GMPLS",
             draft-ietf-pce-gmpls-pcep-extensions, work in progress.



10.2. Informative References

   [RFC3471] Berger, L. (Editor), "Generalized Multi-Protocol Label
             Switching (GMPLS) Signaling Functional Description", RFC
             3471. January 2003.


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

   [RFC5420] Farrel, A. "Encoding of Attributes for MPLS LSP
             Establishment Using Resource Reservation Protocol Traffic
             Engineering (RSVP-TE)", RFC5420, February 2009.

   [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
             Element (PCE) communication Protocol", RFC 5440, March
             2009.[RFC5521] Oki, E, T. Takeda, and A. Farrel,
             "Extensions to the Path Computation Element Communication
             Protocol (PCEP) for Route Exclusions", RFC 5521, April
             2009.

   [RFC6163] Lee, Y. and Bernstein, G. (Editors), and W. Imajuku,
             "Framework for GMPLS and PCE Control of Wavelength
             Switched Optical Networks", RFC 6163, March 2011.

   [RFC7446] Y. Lee, G. Bernstein. (Editors),"Routing and Wavelength
             Assignment Information Model for Wavelength Switched
             Optical Networks", RFC 7446, February 2015.

   [RFC8253] D. Lopez, O. Gonzalez de Dios, Q. Wu, D. Dhody, "PCEPS:
             Usage of TLS to Provide a Secure Transport for the Path
             Computation Element Communication Protocol (PCEP)", RFC
             8253, October 2017.

   [PCEP-LS] Y. Lee, et al., "PCEP Extension for Distribution of Link-
             State and TE information for Optical Networks", draft-lee-
             pce-pcep-ls-optical, work in progress.







11. Contributors










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Authors' Addresses

   Young Lee, Editor
   Huawei Technologies
   1700 Alma Drive, Suite 100
   Plano, TX 75075, USA
   Phone: (972) 509-5599 (x2240)
   Email: leeyoung@huawei.com


   Ramon Casellas, Editor
   CTTC PMT Ed B4 Av.  Carl Friedrich Gauss 7
   08860 Castelldefels (Barcelona)
   Spain
   Phone: (34) 936452916
   Email: ramon.casellas@cttc.es

   Fatai Zhang
   Huawei Technologies
   Email: zhangfatai@huawei.com

   Cyril Margaria
   Nokia Siemens Networks
   St Martin Strasse 76
   Munich,   81541
   Germany
   Phone: +49 89 5159 16934
   Email: cyril.margaria@nsn.com

   Oscar Gonzalez de Dios
   Telefonica Investigacion y Desarrollo
   C/ Emilio Vargas 6
   Madrid,   28043
   Spain
   Phone: +34 91 3374013
   Email: ogondio@tid.es

   Greg Bernstein
   Grotto Networking
   Fremont, CA, USA
   Phone: (510) 573-2237
   Email: gregb@grotto-networking.com







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