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Versions: 00 01 02                                                      
Network Working Group                                            L. Wang
Internet-Draft                                                     Y. Li
Intended status: Standards Track                                     ZTE
Expires: January 17, 2013                                      GY. Zhang
                                                China Academy of Telecom
                                                          Research, MIIT
                                                           July 16, 2012


    OSPF Extensions for Routing Constraint Encoding in Flexible-Grid
                                Networks
          draft-wangl-ccamp-ospf-ext-constraint-flexi-grid-02

Abstract

   In Flexible-Grid networks, network elements and links may impose
   additional routing constraints, which cannot be ignored in Routing
   and Spectrum Assignment (RSA) process.  This document describes the
   requirements of such constraints, and then provides efficient
   encodings to specify how the information is carried.

Status of this Memo

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

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   This Internet-Draft will expire on January 17, 2013.

Copyright Notice

   Copyright (c) 2012 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
   2.  Conventions Used in This Document  . . . . . . . . . . . . . .  3
   3.  Terminologies  . . . . . . . . . . . . . . . . . . . . . . . .  3
   4.  Requirements of Routing Constraint for RSA in
       Flexible-Grid Networks . . . . . . . . . . . . . . . . . . . .  4
     4.1.  Label set  . . . . . . . . . . . . . . . . . . . . . . . .  8
     4.2.  Flexible-Grid Ability Constraint . . . . . . . . . . . . .  8
     4.3.  Optical Signal Compatibility Constraint  . . . . . . . . .  9
     4.4.  switching capability . . . . . . . . . . . . . . . . . . . 10
   5.  Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     5.1.  Label Set  . . . . . . . . . . . . . . . . . . . . . . . . 10
     5.2.  Flexible-Grid Ability and Switching Cpability
           Constraint . . . . . . . . . . . . . . . . . . . . . . . . 14
     5.3.  Optical Signal Compatibility Constraint  . . . . . . . . . 16
   6.  Encoding Example . . . . . . . . . . . . . . . . . . . . . . . 17
     6.1.  Example of Label Set Encoding  . . . . . . . . . . . . . . 17
     6.2.  Example of Flexible-Grid Ability Constraint Encoding . . . 20
     6.3.  Example of Signal Compatibility Encoding . . . . . . . . . 20
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 21
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 21
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 21
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 21
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22



















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1.  Introduction

   Flexible-Grid technique breaks the rigid nature of traditional DWDM
   wavelength Grid, and enables flexible allocation of optical spectrum
   resources to accommodate ultra-high data rate traffic.  In such
   environments, Network elements (such as nodes and Optical-to-
   Electronic/Electronic-to-Optical sub-systems) and links may impose
   additional routing constraints such as available frequency range,
   flexible-grid ability and slot width range on ports/links, asymmetric
   switch connectivity, signal processing limitations of each OE/EO
   system, and so on.  Without considering these constraints, it cannot
   be guaranteed to obtain available results in RSA process especially
   for network scenarios with various Flexible-Grid and Fixed-Grid
   elements, which leads to inefficient routing and high blocking
   probability of end-to-end paths.

   This document describes the requirments of RSA, and then encodes the
   constraints imposed by network elements and links, which could be
   carried in OSPF Messages to flood to each node for efficient RSA.  In
   addition, such information could be conveyed by other mechanisms to a
   Path Computation Element (PCE).  Note that, impairment-related
   constraints are not considered here.


2.  Conventions Used in This Document

   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].


3.  Terminologies

   Center Frequency Granularity (CFG): The minimum step by which the
   center frequency of optical bandwidth can be increased or decreased.
   .

   frequency grid: A frequency grid is a reference set of frequencies
   used to denote allowed nominal central frequencies that may be used
   for defining applications.

   Frequency slot: The frequency range allocated to a slot and
   unavailable to other slots within a flexible grid.  A frequency slot
   is defined by its nominal central frequency and its slot width
   [G.694.1v2].

   [Editor's note: according to ITU-T WP3 Q12 interim meeting [ITU-T
   WD12R2], one or multiple Optical Channels may be transported over a



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   single frequency slot.  If this viewpoint is accepted, the following
   definitions are needed:

   Single-Channel Frequency Slot: a frequency slot associated with a
   single optical channel signal (that carries a single OCh payload).

   Multi-Channel Frequency Slot: a frequency slot associated with
   multiple optical channel signals (i.e. multiple OChs).]

   Frequency Slot Channel: a topological construct that represents a
   piece of spectrum supported by a concatenation of media elements
   (fiber, amplifiers, filters..).  This term is used to identify the
   end-to-end physical layer entity with its corresponding (one or more)
   frequency slots local at each link.

   GMPLS: Generalized Multi-Protocol Label Switching.

   Lowest/Highest frequency: the lowest/highest frequency of a frequency
   slot.

   OCH: Optical Channel

   ROADM: Reconfigurable Optical Add-Drop Multiplexer.

   RSA: Routing and spectrum assignment.

   Slice: the basic slot unit, and the slot width of one slice is equal
   to slot width granularity.

   Slot width: The full width of a frequency slot in a flexible grid
   [G.694.1v2].

   Slot Width Granularity (SWG): the minimum step by which the optical
   filter bandwidth of ROADM can be increased or decreased.
   Accordingly, SWG (GHz) = 2 * CFG (GHz).

   WSON: Wavelength Switched Optical Networks [RFC6163].

   WSS: Wavelength Selective Switch.


4.  Requirements of Routing Constraint for RSA in Flexible-Grid Networks

   In Flexible-Grid network, there is one key problem: how to route and
   allocate spectrum resources for each end-to-end optical channel, so
   to fulfill their requirements in an efficient way?  To address this
   problem, some constraints must be taken into consideration, which are
   listed as follows.



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   -Spectrum availability constraint.

   -Flexible-Grid ability constraint.

   -Asymmetric switch connectivity constraint.

   -Optical signal compatibility constraint.

   -Other constraints.

   The asymmetric switch connectivity constraint in Flexible-Grid
   network could be well addressed by Connectivity matrix sub-TLV used
   in Wavelength Switched Optical Networks (WSON)
   [I-D.ietf-ccamp-general-constraint-encode].  The spectrum
   availability constraint is studied in several drafts
   [I-D.li-ccamp-flexible-grid-label]
   [I-D.zhang-ccamp-flexible-grid-ospf-ext][I-D.dhillon-ccamp-super-chan
   nel-ospfte-ext], and could be represented by Label-set extensions.
   However, these extensions are not complete, so we reorganize the
   Flexible-Grid label-set according to WSON definition.  In addition,
   Flexible-Grid ability constraint (icluding grid type and slot width
   granularity/range) and optical signal conpatibility constraint are
   also necessary for efficient RSA, but few document takes these into
   account. we will describe the requirements and encodings of such
   constraints in this draft.

   Here a general scenario of Flexible-Grid Network is given in order to
   illustrate these requirements.


                 +----+A-E2    B-I1+----+B-E2    C-I1+----+
                 | A  |----------->| B  |----------->| C  |
                 |    |<-----------|    |<-----------|    |
                 +----+A-I2    B-E1+----+B-I2    C-E1+----+
                   O|                O|                O|
               A-I1||A-E1        B-I3||B-E3        C-I2||C-E2
                   ||                ||                ||
                   ||                ||                ||
                   ||                ||                ||
                   ||                ||                ||
               D-E1||D-I1        E-E3||E-I3        F-E2||F-I2
                   |O                |O                |O
                 +----+D-E2    E-I1+----+E-E2    F-I1+----+
                 | D  |----------->| E  |----------->| F  |
                 |    |<-----------|    |<-----------|    |
                 +----+D-I2    E-E1+----+E-I2    F-E1+----+





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     Figure 1. A sample network with both Fixed-Grid and Flexible-Grid
                                 elements



         Tributary Side:        E5 I5 E6 I6
                                O |   O |
                                | |   | |
                                | O   | O
                         +-----------------------+
                         |+-----+         +-----+|
         Line side-1 --->||Split|         |WSS-2||---> Line side-2
         Input (I1)      |+-----+         +-----+|     Output (E2)
         Line side-1 <---||WSS-1|         |Split||<--- Line side-2
         Output  (E1)    |+-----+         +-----+|     Input (I2)
                         |         ROADM         |
                         |+-----+         +-----+|
         Line side-3 --->||Split|         |WSS-4||---> Line side-4
         Input (I3)      |+-----+         +-----+|     Output (E4)
         Line side-3 <---||WSS-3|         |Split||<--- Line side-4
         Output (E3)     |+-----+         +-----+|     Input (I4)
                         +-----------------------+
                                | O   | O
                                | |   | |
                                O |   O |
         Tributary Side:        E7 I7 E8 I8


        Figure 2. A ROADM Composed of WSSs and splitters (Internal
                      connections are not presented)

   Figure 1 shows the network topology, while Figure 2 shows the
   architecture of nodes.  The ROADM of Figure 2 is composed of WSSs and
   splitters.  I1~4/E1~4 are line-side input/output ports, while I5~8/
   E5~8 are tributary-side add/drop ports to/from line-side 1~4
   respectively.  The configuration of each line-side output port is
   shown as follows:














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       +----+---------+-----+------+-----------+---------+---------+
       |Node|Node-Type|Ports| Type |Granularity|Min width|Max width|
       +----+---------+-----+------+-----------+---------+---------+
       |    |         |A-E1 | Flex |    25GHz  |  50GHz  | 300GHz  |
       | A  |  Flex   |-----+------+-----------+---------+---------+
       |    |         |A-E2 | Flex |  12.5GHz  |  50GHz  | 200GHz  |
       +----+---------+-----+------+-----------+---------+---------+
       |    |         |B-E1 | Flex |  12.5GHz  |  50GHz  | 200GHz  |
       |    |         |-----+------+-----------+---------+---------+
       | B  |  Mixed  |B-E2 | Fixed|    50GHz  |  50GHz  |  50GHz  |
       |    |         |-----+------+-----------+---------+---------+
       |    |         |B-E3 | Flex |  12.5GHz  |  50GHz  | 200GHz  |
       +----+---------+-----+------+-----------+---------+---------+
       |    |         |C-E1 | Fixed|    50GHz  |  50GHz  |  50GHz  |
       | C  |  Fixed  |-----+------+-----------+---------+---------+
       |    |         |C-E2 | Fixed|    50GHz  |  50GHz  |  50GHz  |
       +----+---------+-----+------+-----------+---------+---------+
       |    |         |D-E1 | Flex |    25GHz  |  50GHz  | 300GHz  |
       | D  |  Flex   |-----+------+-----------+---------+---------+
       |    |         |D-E2 | Flex |    25GHz  |  50GHz  | 300GHz  |
       +----+---------+-----+------+-----------+---------+---------+
       |    |         |E-E1 | Flex |    25GHz  |  50GHz  | 300GHz  |
       |    |         |-----+------+-----------+---------+---------+
       | E  |  Flex   |E-E2 | Flex |  12.5Ghz  |  50GHz  | 200GHz  |
       |    |         |-----+------+-----------+---------+---------+
       |    |         |E-E3 | Flex |  12.5GHz  |  50GHz  | 200GHz  |
       +----+---------+-----+------+-----------+---------+---------+
       |    |         |F-E1 | Flex |  12.5GHz  |  50GHz  | 200GHz  |
       | F  |  Mixed  |-----+------+-----------+---------+---------+
       |    |         |F-E2 | Fixed|    50GHz  |  50GHz  |  50GHz  |
       +----+---------+-----+------+-----------+---------+---------+


   The granularity denotes the slot width granularity.  The Min-width
   and Max-width denote the slot width range.  There are three types of
   nodes: Node A, node D and node E are Flexible-Grid ROADMs, which only
   consist of Flexible-Grid elements; Node C is a Fixed-Grid ROADM,
   which only consists of Fixed-Grid elements; Node B and Node F are
   Mixed-Grid ROADMs, which consist of both Flexible-Grid and Fixed-Grid
   Elements.  Both Flexible-Grid ROADM and Mixed-Grid ROADM can support
   Flexible-Grid LSPs to accommodate ultra-high data rate traffic such
   as beyond 100G. In addition, the Fixed-Grid ROADM can be smoothly
   updated to Mixed-Grid ROADM by adding Flexible-Grid ports.  With
   appropriate RSA, the network is able to support both Fixed-Grid LSPs
   and Flexible-Grid LSPs in an efficient way.






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4.1.  Label set

   In Flexible-Grid networks, the spectrum assignment is not a local
   matter due to spectral consecutiveness and continuity constraints, so
   it is needed to get the information of which slice may or may not be
   used on each link and node port along the path in RSA process.  For
   example, in the network of Figure 1, when a LSP request from node A
   to node E with 150GHz slot width and route A->B->E arrives, the label
   restriction of input port A-I6, output port E-E7, switch port A-E2,
   B-I1, B-E3, E-I3 and spectrum availability of link AB, BE must be got
   for the spectrum assignment.  All the information is described by the
   label set objects which is decided by the label format.  The
   generalized label for the flexible grid can be referred to
   [I-D.farrkingel-ccamp-flexigrid-lambda-label] including central
   frequency and slot width information.

   As specified in [I-D.li-ccamp-flexible-grid-label] in section 4.1,
   this kind of label format is backward compatible to support the
   traditional 5 ways of wavelength label set encoding
   [I-D.ietf-ccamp-general-constraint-encode].

   o  1.  Inclusive list

   o  2.  Exclusive list

   o  3.  Inclusive range

   o  4.  Exclusive range

   o  5.  Bitmap set

   It can be seen that these 5 types of representations can be easily
   inherited by incorporating the new flexible label into the object.
   Note that in the procedure of flooding, any combination of the 5
   types of label sets is feasible.

4.2.  Flexible-Grid Ability Constraint

   Flexible-Grid ability may include the grid type (Fixed-Grid or
   Flexible-Grid) and slot width granularity/range.  This information
   can be seen as the attribution of network ports with relations to
   links or nodes.  The RSA requirements of such fields are listed as
   follows:

   Firstly, Flexible-Grid WSSs of different companies or product-types
   may have different slot width granularity and range, which may be a
   subset of possible values specified by ITU-T [G.694.1v2], so it
   should be taken into consideration in RSA process to avoid invalid



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   route selection.  For example, in the network of Figure 1, when a
   Flexible-Grid LSP request from node A to node E with 250GHz slot
   width arrives, only the optical channel with a route A->D->E is able
   to carry the traffic due to the slot width range limitations on other
   ports.

   In addition, The slot width granularity of network elements may
   impact the spectral efficiency.  For example, when a Flexible-Grid
   LSP request from node A to node E with 87.5GHz slot width arrives,
   100GHz Slot width must be assigned for the route A->D->E due to 25GHz
   slot width granularity, which performs poor in spectral efficiency.

   FurthermoreGBP[not]Although Flexible-Grid technology may offer full
   backwards compatibility with the standard ITU-T DWDM grids, it is a
   cost-efficient way to consider Flexible-Grid Ability constraints in
   RSA process for Fixed-Grid requirements.  For example, in the network
   of figure 1, when a Fixed-Grid LSP request from node B to node F with
   50GHz slot width arrives, it is a better route of B->C->F than the
   route B->E->F, because that flexible-Grid WSSs are more expensive
   than fixed-grid ones, and routing fixed-Grid requests on fixed-Grid
   elements could leave the Flexible-Grid elements and related spectrum
   resources to subsequent high data rate traffic.

4.3.  Optical Signal Compatibility Constraint

   Optical Signal Compatibility Constraint includes the signal
   processing ability (for example, data rate, FEC and modulation
   format) and modulation-related minimum slot width for each Optical-
   to-Electronic (OE)/Electronic-to-Optical (EO) subsystem.  The RSA
   requirements of such fields are listed as follows:

   Firstly, as described in [I-D.ietf-ccamp-rwa-wson-encode], OE/EO
   subsystems may be limited to process only certain types of optical
   signal in WSON or Flexible-Grid networks, so it is necessary to get
   sufficient information characterizing OE/EO elements in RSA process
   to determine the signal compatibility along the path.  Examples of
   such subsystems include transponders, regenerators and so on.

   In addition, for each Flexible-Grid Label Switch Path, the required
   slot width is determined by the attribution of optical signal.
   However, a client only requests "data rate" as its traffic parameter
   but do not care "slot width", so it is needed to establish the
   mapping relations between data-rate/modulation-format and slot width,
   which should be reflected in optical signal compatibility constraint.
   For example, in the network of Figure 1, when a LSP request from node
   A to Node E with 100Gbit/s data rate arrives, and both the
   transmitter of node A and the responder of node E support optical
   tributary signal class DP-QPSK 100G with the same FEC and



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   corresponding slot width 50GHz, the minimum slot width required by
   this LSP should be 50GHz.

4.4.  switching capability

   According to ITU-T WP3 Q12 interim meeting [ITU-T WD12R2], the media
   layer corresponds to the server layer (flexigrid) and the signal
   layer corresponds to the client layer (OCh).this means the separation
   between the signal and the waveguide that the signal propagates
   through.  For example, one frequency slot channel setup in media
   layer could be seen as a TE-link in signal layer, and carry one
   (single-channel frequency slot) or multiple (multiple-channel
   frequency slot) OCh.

   For control plane, it needs to differentiate signal LSP (OCh) and
   media LSP (frequency-slot channel), and specify the switching
   capability (signal/media) of each interface/TE-link.


5.  Encoding

5.1.  Label Set

   The general format for a label set is in accordance with that in
   [I-D.ietf-ccamp-general-constraint-encode], with a new flag G (1bit)
   representing the grid type of label sets(1~Flexible-Grid DWDM;
   0~Fixed-Grid DWDM):


      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |G| Act.|    Num Labels         |          Length               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                         start Label                           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                         start Label(continue)                 |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     :     Additional fields as necessary per action                 :
     :                                                               :
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   the label format is in accordance with that in
   [I-D.farrkingel-ccamp-flexigrid-lambda-label].

   In the case of Inclusive/Exclusive label lists (0/1), the label set
   format is given 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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1| 0or1| Num Labels (not used) |          Length               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         First Label                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         First Label(continue)                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      :                                                               :
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Last  Label                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Last  Label(continue)                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Note that one label set may contain multiple labels.  The lowest/
   highest frequency of the K-th label is calculated as follows:

   Lowest frequency_k = (central frequency_k) - (slot width_k)/2

   = (193.1 + n_k * C.S.) - (2 * C.S. * m_k)/2

   = (193.1 + (n_k - m_k) * C.S.) THz;

   Highest frequency_k = Lowest frequency_k + slot width_k

   = (193.1 + (n_k + m_k) * C.S.) THz;

   In the case of Inclusive/Exclusive label ranges (2/3), the label set
   format is given 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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1| 2or3| Num Labels(not used)  |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Start Label #1                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Start Label #1(continue)                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     End Label #1                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     End Label #1(continue)                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      :                                                               :
      :                                                               :
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Start Label #n                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Start Label #n(continue)                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     End Label #n                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     End Label #n(continue)                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Note that one label set may contain multiple label ranges.  The value
   of m in start/end label in meaningless on the label set, however, in
   order to keep the integrity of labels and avoid misunderstanding, it
   is set to default value: m = (slot width granularity)/12.5GHz.

   The lowest/highest frequency of the K-th label range is calculated as
   follows:

   Lowest frequency_k = (central frequency_kstart) - (slot width
   granularity)/2

   = (193.1 + n_kstart * C.S.) - C.S.

   = (193.1 + (n_kstart - 1) * C.S.) THz;

   Highest frequency_k = (central frequency_kend) + (slot width
   granularity)/2

   = (193.1 + n_kend * C.S.) + C.S.

   = (193.1 + (n_kend + 1) * C.S.) THz;




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   In the case of bitmap (4), the label set format is given 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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |1|  4  |   Num Labels          |             Length            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                         Start Label                           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                         Start Label(continue)                 |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Bit Map Word #1 (Lowest numerical labels)                  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     :                                                               :
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Bit Map Word #N (Highest numerical labels)                 |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Based on [I-D.ietf-ccamp-general-constraint-encode], Num labels
   denote the number of slices represented by the bit map; where the
   slice denotes the basic slot unit, and the slot width of one slice is
   equal to the slot width granularity.  As there may exist some
   situations that the unused bandwidth between two occupied bandwidth
   is odd times of the central frequency granularity (not integral times
   of the slot with granularity), two bits are needed to represent a
   single slice.  Each bit in the bit map represents a particular label
   of half a slice with a value of 1/0 indicating whether the part is in
   the set or not.  Bit position zero and one represent the lowest slice
   and corresponds to the start label.  The lowest/highest frequency of
   label range represented by bit position K is calculated as follows:

   Lowest frequency_k = (central frequency_start) + (K - 1) * (slot
   width granularity)/2

   = (193.1 + n_start * C.S.) + (K - 1) * C.S.

   = 193.1 + (n_start + K -1) * C.S.;

   Highest frequency_k = Low frequency_k + C.S.

   = 193.1 + (n_start + K) * C.S.

   The size of the bit map is (2 * Num Label) bits, but the bit map is
   padded out to a full multiple of 32 bits so that the TLV is a
   multiple of four bytes.  "Bits that do not represent labels (i.e.,
   those in positions) and beyond SHOULD be set to zero and MUST be



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   ignored" [I-D.ietf-ccamp-general-constraint-encode].

5.2.  Flexible-Grid Ability and Switching Cpability Constraint

   To accommodate the feature of Flexible-Grid Ability and switching
   capability constraint, we extend the Port Label Restriction sub-TLV
   defined in [I-D.ietf-ccamp-general-constraint-encode] for Flexible-
   Grid networks:


       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | MatrixID      | RstType = 5   | Switching Cap.|    Encoding   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |Grid | C.S.  |S|M|Reserved     |   Min-Width   |   Max-Width   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   In WSON network, Matrix ID is used to represent "either the value in
   the corresponding Connectivity Matrix sub-TLV or takes the value OxFF
   to indicate the restriction applies to the port regardless of any
   Connectivity Matrix" [I-D.ietf-ccamp-general-constraint-encode].
   RstType is used to represent the restriction type.  This document
   defines a new RstType value to express the port Flexible-Grid
   Supporting Ability constraint in Flexible-Grid networks:

   5: GRID_ABILITY.

   The meaning of Grid and C.S. is defined in
   [I-D.farrkingel-ccamp-flexigrid-lambda-label], which is shown as
   follows:


                         +---------------+-------+
                         | Grid          | Value |
                         +---------------+-------+
                         | Reserved      |   0   |
                         +---------------+-------+
                         | ITU-T DWDM    |   1   |
                         +---------------+-------+
                         | ITU-T CWDM    |   2   |
                         +---------------+-------+
                         | Flexible DWDM |   3   |
                         +---------------+-------+
                         | Any           | 4(TBA)|
                         +---------------+-------+
                         | Future use    |  5-7  |



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                         +---------------+-------+




                         +-------------+---------+
                         |C.S. (GHz)   |  Value  |
                         +-------------+---------+
                         | Reserved    |    0    |
                         +-------------+---------+
                         |    100      |    1    |
                         +-------------+---------+
                         |    50       |    2    |
                         +-------------+---------+
                         |    25       |    3    |
                         +-------------+---------+
                         |    12.5     |    4    |
                         +-------------+---------+
                         |    6.25     | 5 (TBA) |
                         +-------------+---------+
                         |Future use   | 6 ~ 15  |
                         +-------------+---------+


   A new Grid type "Any" is defined. the reason is explained later in
   this document.

   "Within the fixed grid network, the C.S. value is used to represent
   the channel spacing, as the spacing between adjacent channels is
   constant.  While for flexible grid situation, this field should be
   used to represent central frequency granularity."
   [I-D.farrkingel-ccamp-flexigrid-lambda-label] Accordingly the slot
   width granularity is twice of the C.S..

   Min-Width/Max-Width: 8bits, unsigned integer.  Min-Width/Max-Width
   denotes the minimum/maximum slot width that the ROADM port supports,
   which is an inherent attribution of the network elements.  The
   formula is shown as follows:

   Minimum Slot Width (GHz) = 12.5GHz * Min-Width;

   Maximum Slot Width (GHz) = 12.5GHz * Max-Width;

   For flexible-Grid ports (Grid = 3), the possible values of slot width
   are within the range [Minimum Slot Width, Maximum Slot Width] and
   with the slot width granularity of 2 * C.S.; for Fixed-Grid ports
   (Grid = 1 or 2), Min-Width/Max-Width is meaningless and padded with
   0.  For any port with Grid type "any", it means that the port support



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   any Grid type, any slot width granularity and any slot width range,
   so C.S. and Min-Width/Max-Width are meaningless and padded with 0.
   One example of such port is A-I1, which is comprised of optical
   splitter.

   Note that, the similar field of Min-Width/Max-Width is also included
   in object "BW sub-TLV" proposed by
   [I-D.dhillon-ccamp-super-channel-ospfte-ext].  However, BW sub-TLV is
   mainly used to present the available label set, so it belongs to
   dynamic information according to [RFC6163] and should be flooded
   frequently whenever the link state changes (for example, after the
   setup/teardown of the path traversing the link).  In this document,
   the Port Label Restriction sub-TLV with GRID_ABILITY type is regarded
   as relatively static information, as changes to these properties such
   as Grid, C.S. and Min-Width/Max-Width require hardware upgrades.  It
   is more suitable to carry such information separated from available
   label set in order to alleviate unnecessary flooding.

   A new switching capability is defined here: 151, Spectrum Switch
   Capable (SSC).  When the switching capability is SSC, the field S
   indicates the signal-layer switch capability (1-support, 0-not),
   while the field M indicates the media-layer switch capability
   (1-support, 0-not).

   Other port label restrictions have no difference with that in
   [I-D.ietf-ccamp-general-constraint-encode].

5.3.  Optical Signal Compatibility Constraint

   To accommodate the feature of Optical Signal Compatibility
   Constraint, we extend the Modulation Type sub-TLV defined in
   [I-D.ietf-ccamp-rwa-wson-encode] for Flexible-Grid networks:


       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |S|I|        Modulation ID         |          Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       m       |   Possible additional modulation parameters   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      :   the modulation ID                                           :
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   The meaning of S, I and Modulation ID is in accordance with that of
   [I-D.ietf-ccamp-rwa-wson-encode].




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   This document adds a new field "m" (8bit) to represent the minimum
   slot width requirement for corresponding Modulation ID:

   Minimum Slot Width = 12.5GHz * m.

   Note that the modulation type sub-TLV may contain multiple modulation
   IDs, which means the transmitter/responder/transponder/regennerator
   support multiple data rate/modulation format.

   This sub-TLV establishes mapping relations between data rate/
   modulation format (Modulation ID) and slot width.  In addition, it
   also provides the signal processing ability for each OE/EO element in
   the network.  However, FEC may impact the value of m, but it is not
   discussed here and leaved for further study.  New values of
   Modulation ID should be defined for ultra-high speed transmission,
   but it depends on transmission technique and not specified in this
   document.

   Other signal compatibility constraints have no difference with that
   in [I-D.ietf-ccamp-rwa-wson-encode].


6.  Encoding Example

6.1.  Example of Label Set Encoding

   Taking the network of figure 1 as an example, the available spectral
   resource of link AB is shown in figure 3.


               #1    Lowest    #2  Highest               #3
             |-|-|   |---------|---------|       |-------|-------|
               |               |Center Freq.             |       ^
             |1 1 0 0 1 1 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1 1 1 1 1 1|
           __|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|__
         n= -16 -14 -12 -10 -8  -6  -4  -2   0   2   4   6   8   10
               |                                             |___|
             |_|_|                                          12.5GHz
               |
             slice


               Figure 3. Spectral resource state of link AB

   In figure 3, the spectral resource is from 193.1THz - 16 * 6.25GHz to
   193.1THz + 10 * 6.25GHz.  For label list type, the label set format
   is given 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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1|  0  | Num Labels(not used)  |             Length(28)        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  3  |C.S.(5)|    Identifier   |              n(-15)           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       m(1)    |                  Reserved                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  3  |C.S.(5)|    Identifier   |              n(-7)            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       m(5)    |                  Reserved                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  3  |C.S.(5)|    Identifier   |              n(6)             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       m(4)    |                  Reserved                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   For label range type, the label set format is given 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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1|  2  | Num Labels(not used)  |             Length(52)        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  3  |C.S.(5)|    Identifier   |              n(-15)           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       m(1)    |                  Reserved                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  3  |C.S.(5)|    Identifier   |              n(-15)           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       m(1)    |                  Reserved                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  3  |C.S.(5)|    Identifier   |              n(-11)           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       m(1)    |                  Reserved                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  3  |C.S.(5)|    Identifier   |              n(-3)            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       m(1)    |                  Reserved                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  3  |C.S.(5)|    Identifier   |              n(3)             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       m(1)    |                  Reserved                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  3  |C.S.(5)|    Identifier   |              n(9)             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       m(1)    |                  Reserved                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   For bitmap type, the label set format is given 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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1|  4  | Num Labels(26)        |             Length(16)        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  3  |C.S.(5)|    Identifier   |              n(-15)           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       m(1)    |                  Reserved                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1|1|0|0|1|1|1|1|1|1|1|1|1|1|0|0|0|0|1|1|1|1|1|1|1|1|0|0|0|0|0|0|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+






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6.2.  Example of Flexible-Grid Ability Constraint Encoding

   Taking the network of figure 1 as an example, the Flexible-Grid
   ability constraint of A-E1 can be encoded as follows:


        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | MatrixID(0xff)| RstType(5)    |        Reserved               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  3  |C.S.(5)|    Reserved     |  Min-Width(4) | Max-Width(16) |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   The Flexible-Grid ability constraint of A-E2 can be encoded 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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | MatrixID(0xff)| RstType(5)    |        Reserved               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  3  |C.S.(4)|    Reserved     |  Min-Width(4) | Max-Width(24) |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   The Flexible-Grid ability constraint of B-E2 can be encoded 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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | MatrixID(0xff)| RstType(5)    |        Reserved               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  1  |C.S.(2)|    Reserved     |  Min-Width(0) | Max-Width(0)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


6.3.  Example of Signal Compatibility Encoding

   Assuming an optical transmitter can support the following modulation
   types: optical tributary signal class DP-QPSK 100G (minimum slot
   width: 50GHz); optical tributary signal class DP-BPSK 100G (minimum
   slot width: 100GHz).  T he Modulation Type sub-TLV is given 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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1|0|       DP-QPSK 100G        |             Length(8)         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      m(4)     |   Possible additional modulation parameters   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1|0|       DP-BPSK 100G        |             Length(8)         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      m(8)     |   Possible additional modulation parameters   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



7.  Security Considerations


8.  IANA Considerations

   TBD.


9.  References

9.1.  Normative References

   [G.694.1v2]
              ITU-T Recommendation G.694.1, "Spectral grids for WDM
              apllications: DWDM frequency grid", November 2011.

   [ITU-T WD12R2]
              International Telecomunications Union, WD12R2, Q12-SG15,
              "Proposed media layer terminology for G.872", May 2012.

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

   [RFC6163]  Lee, Y., Bernstain, G., and W. Imajuku, "Framework for
              GMPLS and Path Computation Element Control of Wavelength
              Switched Optical Networks", RFC 6163, April 2011.

9.2.  Informative References

   [I-D.dhillon-ccamp-super-channel-ospfte-ext]
              Dhillon, A., Hussain, I., Rao, RJ., and M. Sosa, "OSPFTE
              extension to support GMPLS for Flex Grid", October 2011.

   [I-D.farrkingel-ccamp-flexigrid-lambda-label]



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              Farrel, A., King, D., Li, Y., Zhang, F., and R. Casellas,
              "Generalized Labels for the Flexi-Grid in Lambda-Switch-
              Capable (LSC) Label Switching Routers", October 2011.

   [I-D.hussain-ccamp-super-channel-label]
              Hussain, I., Dhillon, A., Pan, Z., Sosa, M., Basch, B.,
              Liu, S., and A-G. Malis, "Generalized Label for Super-
              Channel Assignment on Flexible Grid", October 2011.

   [I-D.ietf-ccamp-general-constraint-encode]
              Bernstein, G., Lee, Y., Li, D., Imajuku, W., and JR. Han,
              "General Network Element Constraint Encoding for GMPLS
              Controlled Networks", May 2011.

   [I-D.ietf-ccamp-rwa-wson-encode]
              Bernstein, G., Lee, Y., Li, D., Imajuku, W., and JR. Han,
              "Routing and Wavelength Assignment Information Encoding
              for Wavelength Switched Optical Networks", October 2011.

   [I-D.li-ccamp-flexible-grid-label]
              Li, Y., Zhang, F., and R. Casellas, "Flexible Grid Label
              Format in Wavelength Switched Optical Network", July 2011.

   [I-D.zhang-ccamp-flexible-grid-ospf-ext]
              Zhang, FT., Zi, XB., Casellas, R., Gonzales-de-Dios, O.,
              and D. Ceccarelli, "GMPLS OSPF-TE Extensions in support of
              Flexible-Grid in DWDM Networks", October 2011.

   [I-D.zhang-ccamp-flexible-grid-requirements]
              Zhang, FT., Zi, XB., Gonzales-de-Dios, O., and R.
              Casellas, "Requirements for GMPLS Control of Flexible
              Grids", October 2011.

   [I-D.zhang-ccamp-flexible-grid-rsvp-te-ext]
              Zhang, FT., Gonzales-de-Dios, O., and D. Ceccarelli,
              "RSVP-TE Signaling Extensions in support of Flexible
              Grid", October 2011.

   [I-D.zhangj-ccamp-flexi-grid-ospf-te-ext]
              Zhang, J., Zhao, YL., and ZY. Yu, "OSPF-TE Protocol
              Extension for Constraint-aware RSA in Flexi-Grid
              Networks", October 2011.









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Authors' Addresses

   Lei Wang
   ZTE
   No.19, Huayuan East Road, Haidian District
   Beijing  100191
   P.R.China

   Phone: +86 13811440067
   Email: wang.lei131@zte.com.cn (hechen0001@gmail.com)
   URI:   http://www.zte.com.cn/


   Yao Li
   ZTE
   P.R.China

   Phone: +86 025 52871109
   Email: li.yao3@zte.com.cn
   URI:   http://www.zte.com.cn/


   Guoying Zhang
   China Academy of Telecom Research, MIIT
   No.52 Huayuan Beilu, Haidian District
   Beijing  100083
   P.R.China

   Email: zhangguoying@mail.ritt.com.cn






















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