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+Internet Engineering Task Force (IETF)                       Y. Lee, Ed.
+Request for Comments: 7446                                        Huawei
+Category: Informational                                G. Bernstein, Ed.
+ISSN: 2070-1721                                        Grotto Networking
+                                                                   D. Li
+                                                                  Huawei
+                                                              W. Imajuku
+                                                                     NTT
+                                                           February 2015
+
+
+          Routing and Wavelength Assignment Information Model
+                for Wavelength Switched Optical Networks
+
+Abstract
+
+   This document provides a model of information needed by the Routing
+   and Wavelength Assignment (RWA) process in Wavelength Switched
+   Optical Networks (WSONs).  The purpose of the information described
+   in this model is to facilitate constrained optical path computation
+   in WSONs.  This model takes into account compatibility constraints
+   between WSON signal attributes and network elements but does not
+   include constraints due to optical impairments.  Aspects of this
+   information that may be of use to other technologies utilizing a
+   GMPLS control plane are discussed.
+
+Status of This Memo
+
+   This document is not an Internet Standards Track specification; it is
+   published for informational purposes.
+
+   This document is a product of the Internet Engineering Task Force
+   (IETF).  It represents the consensus of the IETF community.  It has
+   received public review and has been approved for publication by the
+   Internet Engineering Steering Group (IESG).  Not all documents
+   approved by the IESG are a candidate for any level of Internet
+   Standard; see Section 2 of RFC 5741.
+
+   Information about the current status of this document, any errata,
+   and how to provide feedback on it may be obtained at
+   http://www.rfc-editor.org/info/rfc7446.
+
+
+
+
+
+
+
+
+
+
+Lee, et al.                   Informational                     [Page 1]
+
+RFC 7446                 WSON Information Model            February 2015
+
+
+Copyright Notice
+
+   Copyright (c) 2015 IETF Trust and the persons identified as the
+   document authors.  All rights reserved.
+
+   This document is subject to BCP 78 and the IETF Trust's Legal
+   Provisions Relating to IETF Documents
+   (http://trustee.ietf.org/license-info) in effect on the date of
+   publication of this document.  Please review these documents
+   carefully, as they describe your rights and restrictions with respect
+   to this document.  Code Components extracted from this document must
+   include Simplified BSD License text as described in Section 4.e of
+   the Trust Legal Provisions and are provided without warranty as
+   described in the Simplified BSD License.
+
+Table of Contents
+
+   1. Introduction ....................................................3
+   2. Terminology .....................................................3
+   3. Routing and Wavelength Assignment Information Model .............3
+      3.1. Dynamic and Relatively Static Information ..................4
+   4. Node Information (General) ......................................4
+      4.1. Connectivity Matrix ........................................5
+   5. Node Information (WSON Specific) ................................5
+      5.1. Resource Accessibility/Availability ........................7
+      5.2. Resource Signal Constraints and Processing Capabilities ...11
+      5.3. Compatibility and Capability Details ......................12
+           5.3.1. Shared Input or Output Indication ..................12
+           5.3.2. Optical Interface Class List .......................12
+           5.3.3. Acceptable Client Signal List ......................13
+           5.3.4. Processing Capability List .........................13
+   6. Link Information (General) .....................................13
+      6.1. Administrative Group ......................................14
+      6.2. Interface Switching Capability Descriptor .................14
+      6.3. Link Protection Type (for This Link) ......................14
+      6.4. Shared Risk Link Group Information ........................14
+      6.5. Traffic Engineering Metric ................................15
+      6.6. Port Label Restrictions ...................................15
+           6.6.1. Port-Wavelength Exclusivity Example ................17
+   7. Dynamic Components of the Information Model ....................18
+      7.1. Dynamic Link Information (General) ........................19
+      7.2. Dynamic Node Information (WSON Specific) ..................19
+   8. Security Considerations ........................................19
+   9. References .....................................................20
+      9.1. Normative References ......................................20
+      9.2. Informative References ....................................21
+   Contributors ......................................................22
+   Authors' Addresses ................................................23
+
+
+
+Lee, et al.                   Informational                     [Page 2]
+
+RFC 7446                 WSON Information Model            February 2015
+
+
+1.  Introduction
+
+   The purpose of the WSON information model described in this document
+   is to facilitate constrained optical path computation, and as such it
+   is not a general-purpose network management information model.  This
+   constraint is frequently referred to as the "wavelength continuity"
+   constraint, and the corresponding constrained optical path
+   computation is known as the Routing and Wavelength Assignment (RWA)
+   problem.  Hence, the information model must provide sufficient
+   topology and wavelength restriction and availability information to
+   support this computation.  More details on the RWA process and WSON
+   subsystems and their properties can be found in [RFC6163].  The model
+   defined here includes constraints between WSON signal attributes and
+   network elements but does not include optical impairments.
+
+   In addition to presenting an information model suitable for path
+   computation in WSON, this document also highlights model aspects that
+   may have general applicability to other technologies utilizing a
+   GMPLS control plane.  The portion of the information model applicable
+   to technologies beyond WSON is referred to as "general" to
+   distinguish it from the "WSON-specific" portion that is applicable
+   only to WSON technology.
+
+2.  Terminology
+
+   Refer to [RFC6163] for definitions of Reconfigurable Optical Add/Drop
+   Multiplexer (ROADM), RWA, Wavelength Conversion, Wavelength Division
+   Multiplexing (WDM), WSON, and other related terminology used in this
+   document.
+
+3.  Routing and Wavelength Assignment Information Model
+
+   The WSON RWA information model in this document comprises four
+   categories of information.  The categories are independent of whether
+   the information comes from a switching subsystem or from a line
+   subsystem -- a switching subsystem refers to WSON nodes such as a
+   ROADM or an Optical Add/Drop Multiplexer (OADM), and a line subsystem
+   refers to devices such as WDM or Optical Amplifier.  The categories
+   are these:
+
+   o  Node Information
+
+   o  Link Information
+
+   o  Dynamic Node Information
+
+   o  Dynamic Link Information
+
+
+
+
+Lee, et al.                   Informational                     [Page 3]
+
+RFC 7446                 WSON Information Model            February 2015
+
+
+   Note that this is roughly the categorization used in Section 7 of
+   [G.7715].
+
+   In the following, where applicable, the Reduced Backus-Naur Form
+   (RBNF) syntax of [RBNF] is used to aid in defining the RWA
+   information model.
+
+3.1.  Dynamic and Relatively Static Information
+
+   All the RWA information of concern in a WSON network is subject to
+   change over time.  Equipment can be upgraded; links may be placed in
+   or out of service and the like.  However, from the point of view of
+   RWA computations, there is a difference between information that can
+   change with each successive connection establishment in the network
+   and information that is relatively static and independent of
+   connection establishment.  A key example of the former is link
+   wavelength usage since this can change with connection setup/teardown
+   and this information is a key input to the RWA process.  Examples of
+   relatively static information are the potential port connectivity of
+   a WDM ROADM, and the channel spacing on a WDM link.
+
+   This document separates, where possible, dynamic and static
+   information so that these can be kept separate in possible encodings.
+   This allows for separate updates of these two types of information,
+   thereby reducing processing and traffic load caused by the timely
+   distribution of the more dynamic RWA WSON information.
+
+4.  Node Information (General)
+
+   The node information described here contains the relatively static
+   information related to a WSON node.  This includes connectivity
+   constraints amongst ports and wavelengths since WSON switches can
+   exhibit asymmetric switching properties.  Additional information
+   could include properties of wavelength converters in the node, if any
+   are present.  In [Switch] it was shown that the wavelength
+   connectivity constraints for a large class of practical WSON devices
+   can be modeled via switched and fixed connectivity matrices along
+   with corresponding switched and fixed port constraints.  These
+   connectivity matrices are included with the node information, while
+   the switched and fixed port wavelength constraints are included with
+   the link information.
+
+   Formally,
+
+   <Node_Information> ::= <Node_ID> [<ConnectivityMatrix>...]
+
+   Where the Node_ID would be an appropriate identifier for the node
+   within the WSON RWA context.
+
+
+
+Lee, et al.                   Informational                     [Page 4]
+
+RFC 7446                 WSON Information Model            February 2015
+
+
+   Note that multiple connectivity matrices are allowed and hence can
+   fully support the most-general cases enumerated in [Switch].
+
+4.1.  Connectivity Matrix
+
+   The connectivity matrix (ConnectivityMatrix) represents either the
+   potential connectivity matrix for asymmetric switches (e.g., ROADMs
+   and such) or fixed connectivity for an asymmetric device such as a
+   multiplexer.  Note that this matrix does not represent any particular
+   internal blocking behavior but indicates which input ports and
+   wavelengths could possibly be connected to a particular output port.
+   For a switch or ROADM, representing blocking that is dependent on the
+   internal state is beyond the scope of this document.  Due to its
+   highly implementation-dependent nature, it would most likely not be
+   subject to standardization in the future.  The connectivity matrix is
+   a conceptual M by N matrix representing the potential switched or
+   fixed connectivity, where M represents the number of input ports and
+   N the number of output ports.  This is a "conceptual" matrix since
+   the matrix tends to exhibit structure that allows for very compact
+   representations that are useful for both transmission and path
+   computation.
+
+   Note that the connectivity matrix information element can be useful
+   in any technology context where asymmetric switches are utilized.
+
+   <ConnectivityMatrix> ::= <MatrixID>
+
+                            <ConnType>
+
+                            <Matrix>
+
+   Where
+
+   <MatrixID> is a unique identifier for the matrix.
+
+   <ConnType> can be either 0 or 1 depending upon whether the
+   connectivity is either fixed or switched.
+
+   <Matrix> represents the fixed or switched connectivity in that
+   Matrix(i, j) = 0 or 1 depending on whether input port i can connect
+   to output port j for one or more wavelengths.
+
+5.  Node Information (WSON Specific)
+
+   As discussed in [RFC6163], a WSON node may contain electro-optical
+   subsystems such as regenerators, wavelength converters or entire
+   switching subsystems.  The model present here can be used in
+   characterizing the accessibility and availability of limited
+
+
+
+Lee, et al.                   Informational                     [Page 5]
+
+RFC 7446                 WSON Information Model            February 2015
+
+
+   resources such as regenerators or wavelength converters as well as
+   WSON signal attribute constraints of electro-optical subsystems.  As
+   such, this information element is fairly specific to WSON
+   technologies.
+
+   In this document, the term "resource" is used to refer to a physical
+   component of a WSON node such as a regenerator or a wavelength
+   converter.  Multiple instances of such components are often present
+   within a single WSON node.  This term is not to be confused with the
+   concept of forwarding or switching resources such as bandwidth or
+   lambdas.
+
+   A WSON node may include regenerators or wavelength converters
+   arranged in a shared pool.  As discussed in [RFC6163], a WSON node
+   can also include WDM switches that use optical-electronic-optical
+   (OEO) processing.  There are a number of different approaches used in
+   the design of WDM switches containing regenerator or converter pools.
+   However, from the point of view of path computation, the following
+   need to be known:
+
+   1.  The nodes that support regeneration or wavelength conversion.
+
+   2.  The accessibility and availability of a wavelength converter to
+       convert from a given input wavelength on a particular input port
+       to a desired output wavelength on a particular output port.
+
+   3.  Limitations on the types of signals that can be converted and the
+       conversions that can be performed.
+
+   Since resources tend to be packaged together in blocks of similar
+   devices, e.g., on line cards or other types of modules, the
+   fundamental unit of identifiable resource in this document is the
+   "resource block".
+
+   A resource block is a collection of resources from the same WSON node
+   that are grouped together for administrative reasons and for ease of
+   encoding in the protocols.  All resources in the same resource block
+   behave in the same way and have similar characteristics relevant to
+   the optical system, e.g., processing properties, accessibility, etc.
+
+   A resource pool is a collection of resource blocks for the purpose of
+   representing throughput or cross-connect capabilities in a WSON node.
+   A resource pool associates input ports or links on the node with
+   output ports or links and is used to indicate how signals may be
+   passed from an input port or link to an output port or link by way of
+   a resource block (in other words, by way of a resource).  A resource
+   pool may, therefore, be modeled as a matrix.
+
+
+
+
+Lee, et al.                   Informational                     [Page 6]
+
+RFC 7446                 WSON Information Model            February 2015
+
+
+   A resource block may be present in multiple resource pools.
+
+   This leads to the following formal high-level model:
+
+   <Node_Information> ::= <Node_ID>
+
+                          [<ConnectivityMatrix>...]
+
+                          [<ResourcePool>]
+
+   Where
+
+   <ResourcePool> ::= <ResourceBlockInfo>...
+
+                     [<ResourceAccessibility>...]
+
+                     [<ResourceWaveConstraints>...]
+
+                     [<RBPoolState>]
+
+   First, the accessibility of resource blocks is addressed; then, their
+   properties are discussed.
+
+5.1.  Resource Accessibility/Availability
+
+   A similar technique as used to model ROADMs, and optical switches can
+   be used to model regenerator/converter accessibility.  This technique
+   was generally discussed in [RFC6163] and consisted of a matrix to
+   indicate possible connectivity along with wavelength constraints for
+   links/ports.  Since regenerators or wavelength converters may be
+   considered a scarce resource, it is desirable that the model include,
+   if desired, the usage state (availability) of individual regenerators
+   or converters in the pool.  Models that incorporate more state to
+   further reveal blocking conditions on input or output to particular
+   converters are for further study and not included here.
+
+   The three-stage model is shown schematically in Figures 1 and 2.  The
+   difference between the two figures is that in Figure 1 it's assumed
+   that each signal that can get to a resource block may do so, while in
+   Figure 2 the access to sets of resource blocks is via a shared fiber
+   that imposes its own wavelength collision constraint.  Figure 1 shows
+   that there can be more than one input to each resource block since
+   each input represents a single wavelength signal, while Figure 2
+   shows a single WDM input or output, e.g., a fiber, to/from each set
+   of blocks.
+
+
+
+
+
+
+Lee, et al.                   Informational                     [Page 7]
+
+RFC 7446                 WSON Information Model            February 2015
+
+
+   This model assumes N input ports (fibers), P resource blocks
+   containing one or more identical resources (e.g., wavelength
+   converters), and M output ports (fibers).  Since not all input ports
+   can necessarily reach each resource block, the model starts with a
+   resource pool input matrix RI(i,p) = {0,1} depending on whether input
+   port i can potentially reach resource block p.
+
+   Since not all wavelengths can necessarily reach all the resources or
+   the resources may have limited input wavelength range, the model has
+   a set of relatively static input port constraints for each resource.
+   In addition, if the access to a set of resource blocks is via a
+   shared fiber (Figure 2), this would impose a dynamic wavelength
+   availability constraint on that shared fiber.  The resource block
+   input port constraint is modeled via a static wavelength set
+   mechanism, and the case of shared access to a set of blocks is
+   modeled via a dynamic wavelength set mechanism.
+
+   Next, a state vector RA(j) = {0,...,k} is used to track the number of
+   resources in resource block j in use.  This is the only state kept in
+   the resource pool model.  This state is not necessary for modeling
+   "fixed" transponder system or full OEO switches with WDM interfaces,
+   i.e., systems where there is no sharing.
+
+   After that, a set of static resource output wavelength constraints
+   and possibly dynamic shared output fiber constraints maybe used.  The
+   static constraints indicate what wavelengths a particular resource
+   block can generate or is restricted to generating, e.g., a fixed
+   regenerator would be limited to a single lambda.  The dynamic
+   constraints would be used in the case where a single shared fiber is
+   used to output the resource block (Figure 2).
+
+   Finally, to complete the model, a resource pool output matrix RE(p,k)
+   = {0,1} depending on whether the output from resource block p can
+   reach output port k, may be used.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Lee, et al.                   Informational                     [Page 8]
+
+RFC 7446                 WSON Information Model            February 2015
+
+
+      I1   +-------------+                       +-------------+ O1
+     ----->|             |      +--------+       |             |----->
+      I2   |             +------+ Rb #1  +-------+             | O2
+     ----->|             |      +--------+       |             |----->
+           |             |                       |             |
+           | Resource    |      +--------+       |  Resource   |
+           | Pool        +------+        +-------+  Pool       |
+           |             |      + Rb #2  +       |             |
+           | Input       +------+        +-------|  Output     |
+           | Connection  |      +--------+       |  Connection |
+           | Matrix      |           .           |  Matrix     |
+           |             |           .           |             |
+           |             |           .           |             |
+      IN   |             |      +--------+       |             | OM
+     ----->|             +------+ Rb #P  +-------+             |----->
+           |             |      +--------+       |             |
+           +-------------+   ^               ^   +-------------+
+                             |               |
+                             |               |
+                             |               |
+                             |               |
+
+                    Input wavelength      Output wavelength
+                    constraints for       constraints for
+                    each resource         each resource
+
+   Note: Rb is a resource block.
+
+           Figure 1: Schematic Diagram of the Resource Pool Model
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Lee, et al.                   Informational                     [Page 9]
+
+RFC 7446                 WSON Information Model            February 2015
+
+
+    I1   +-------------+                       +-------------+ O1
+   ----->|             |      +--------+       |             |----->
+    I2   |             +======+ Rb #1  +-+     |             | O2
+   ----->|             |      +--------+ |     |             |----->
+         |             |                 |=====|             |
+         | Resource    |      +--------+ |     |  Resource   |
+         | Pool        |    +-+ Rb #2  +-+     |  Pool       |
+         |             |    | +--------+       |             |
+         | Input       |====|                  |  Output     |
+         | Connection  |    | +--------+       |  Connection |
+         | Matrix      |    +-| Rb #3  |=======|  Matrix     |
+         |             |      +--------+       |             |
+         |             |           .           |             |
+         |             |           .           |             |
+         |             |           .           |             |
+    IN   |             |      +--------+       |             | OM
+   ----->|             +======+ Rb #P  +=======+             |----->
+         |             |      +--------+       |             |
+         +-------------+   ^               ^   +-------------+
+                           |               |
+                           |               |
+                           |               |
+               Single (shared) fibers for block input and output
+
+                Input wavelength          Output wavelength
+                availability for          availability for
+                each block input fiber    each block output fiber
+
+   Note: Rb is a resource block.
+
+    Figure 2: Schematic Diagram of the Resource Pool Model with
+                    Shared Block Accessibility
+
+   Formally, the model can be specified as:
+
+   <ResourceAccessibility> ::= <PoolInputMatrix>
+
+                               <PoolOutputMatrix>
+
+
+   <ResourceWaveConstraints> ::= <InputWaveConstraints>
+
+                                 <OutputWaveConstraints>
+
+
+   <RBSharedAccessWaveAvailability> ::= [<InAvailableWavelengths>]
+
+                                        [<OutAvailableWavelengths>]
+
+
+
+Lee, et al.                   Informational                    [Page 10]
+
+RFC 7446                 WSON Information Model            February 2015
+
+
+   <RBPoolState> ::=    <ResourceBlockID>
+
+                        <NumResourcesInUse>
+
+                        [<RBSharedAccessWaveAvailability>]
+
+                        [<RBPoolState>]
+
+   Note that, except for <RBPoolState>, all the components of
+   <ResourcePool> are relatively static.  Also, the
+   <InAvailableWavelengths> and <OutAvailableWavelengths> are only used
+   in the cases of shared input or output access to the particular
+   block.  See the resource block information in the next section for
+   how this is specified.
+
+5.2.  Resource Signal Constraints and Processing Capabilities
+
+   The wavelength conversion abilities of a resource (e.g., regenerator,
+   wavelength converter) were modeled in the <OutputWaveConstraints>
+   previously discussed.  As discussed in [RFC6163], the constraints on
+   an electro-optical resource can be modeled in terms of input
+   constraints, processing capabilities, and output constraints:
+
+   <ResourceBlockInfo> ::= <ResourceBlockSet>
+
+                           [<InputConstraints>]
+
+                           [<ProcessingCapabilities>]
+
+                           [<OutputConstraints>]
+
+   Where  <ResourceBlockSet> is a list of resource block identifiers
+   with the same characteristics.  If this set is missing, the
+   constraints are applied to the entire network element.
+
+   The <InputConstraints> are constraints are based on signal
+   compatibility and/or shared access constraint indication.  The
+   details of these constraints are defined in Section 5.3.
+
+   <InputConstraints> ::= <SharedInput>
+
+                          [<OpticalInterfaceClassList>]
+
+                          [<ClientSignalList>]
+
+   The <ProcessingCapabilities> are important operations that the
+   resource (or network element) can perform on the signal.  The details
+   of these capabilities are defined in Section 5.3.
+
+
+
+Lee, et al.                   Informational                    [Page 11]
+
+RFC 7446                 WSON Information Model            February 2015
+
+
+   <ProcessingCapabilities> ::= [<NumResources>]
+
+                                [<RegenerationCapabilities>]
+
+                                [<FaultPerfMon>]
+
+                                [<VendorSpecific>]
+
+   The <OutputConstraints> are either restrictions on the properties of
+   the signal leaving the block, options concerning the signal
+   properties when leaving the resource, or shared fiber output
+   constraint indication.
+
+   <OutputConstraints> := <SharedOutput>
+
+                          [<OpticalInterfaceClassList>]
+
+                          [<ClientSignalList>]
+
+5.3.  Compatibility and Capability Details
+
+5.3.1.  Shared Input or Output Indication
+
+   As discussed in Section 5.2 and shown in Figure 2, the input or
+   output access to a resource block may be via a shared fiber.  The
+   <SharedInput> and <SharedOutput> elements are indicators for this
+   condition with respect to the block being described.
+
+5.3.2.  Optical Interface Class List
+
+      <OpticalInterfaceClassList> ::= <OpticalInterfaceClass> ...
+
+   The Optical Interface Class is a unique number that identifies all
+   information related to optical characteristics of a physical
+   interface.  The class may include other optical parameters related to
+   other interface properties.  A class always includes signal
+   compatibility information.
+
+   The content of each class is out of the scope of this document and
+   can be defined by other entities (e.g., the ITU, optical equipment
+   vendors, etc.).
+
+   Since even current implementation of physical interfaces may support
+   different optical characteristics, a single interface may support
+   multiple interface classes.  Which optical interface class is used
+   among all the ones available for an interface is out of the scope of
+   this document but is an output of the RWA process.
+
+
+
+
+Lee, et al.                   Informational                    [Page 12]
+
+RFC 7446                 WSON Information Model            February 2015
+
+
+5.3.3.  Acceptable Client Signal List
+
+   The list is simply:
+
+   <ClientSignalList>::=[<G-PID>]...
+
+   Where the Generalized Protocol Identifiers (G-PID) object represents
+   one of the IETF-standardized G-PID values as defined in [RFC3471] and
+   [RFC4328].
+
+5.3.4.  Processing Capability List
+
+   The ProcessingCapabilities are defined in Section 5.2.
+
+   The processing capability list sub-TLV is a list of processing
+   functions that the WSON network element (NE) can perform on the
+   signal including:
+
+      1.  number of resources within the block
+
+      2.  regeneration capability
+
+      3.  fault and performance monitoring
+
+      4.  vendor-specific capability
+
+   Note that the code points for fault and performance monitoring and
+   vendor-specific capability are subject to further study.
+
+6.  Link Information (General)
+
+   MPLS-TE routing protocol extensions for OSPF [RFC3630] and IS-IS
+   [RFC5305], along with GMPLS routing protocol extensions for OSPF
+   [RFC4203] and IS-IS [RFC5307] provide the bulk of the relatively
+   static link information needed by the RWA process.  However, WSONs
+   bring in additional link-related constraints.  These stem from
+   characterizing WDM line systems, restricting laser transmitter
+   tuning, and switching subsystem port wavelength constraints, e.g.,
+   "colored" ROADM drop ports.
+
+   The following syntax summarizes both information from existing GMPLS
+   routing protocols and new information that may be needed by the RWA
+   process.
+
+
+
+
+
+
+
+
+Lee, et al.                   Informational                    [Page 13]
+
+RFC 7446                 WSON Information Model            February 2015
+
+
+   <LinkInfo> ::=  <LinkID>
+
+                   [<AdministrativeGroup>]
+
+                   [<InterfaceCapDesc>]
+
+                   [<Protection>]
+
+                   [<SRLG>...]
+
+                   [<TrafficEngineeringMetric>]
+
+                   [<PortLabelRestriction>...]
+
+   Note that these additional link characteristics only apply to line-
+   side ports of a WDM system or add/drop ports pertaining to the
+   resource pool (e.g., regenerator or wavelength converter pool).  The
+   advertisement of input/output tributary ports is not intended here.
+
+6.1.  Administrative Group
+
+   Administrative Group: Defined in [RFC3630] and extended for MPLS-TE
+   [RFC7308].  Each set bit corresponds to one administrative group
+   assigned to the interface.  A link may belong to multiple groups.
+   This is a configured quantity and can be used to influence routing
+   decisions.
+
+6.2.  Interface Switching Capability Descriptor
+
+   InterfaceSwCapDesc: Defined in [RFC4202]; lets us know the different
+   switching capabilities on this GMPLS interface.  In both [RFC4203]
+   and [RFC5307], this information gets combined with the maximum Link
+   State Protocol Data Unit (LSP) bandwidth that can be used on this
+   link at eight different priority levels.
+
+6.3.  Link Protection Type (for This Link)
+
+   Protection: Defined in [RFC4202] and implemented in [RFC4203] and
+   [RFC5307].  Used to indicate what protection, if any, is guarding
+   this link.
+
+6.4.  Shared Risk Link Group Information
+
+   SRLG: Defined in [RFC4202] and implemented in [RFC4203] and
+   [RFC5307].  This allows for the grouping of links into shared risk
+   groups, i.e., those links that are likely, for some reason, to fail
+   at the same time.
+
+
+
+
+Lee, et al.                   Informational                    [Page 14]
+
+RFC 7446                 WSON Information Model            February 2015
+
+
+6.5.  Traffic Engineering Metric
+
+   TrafficEngineeringMetric: Defined in [RFC3630] and [RFC5305].  This
+   allows for the identification of a data-channel link metric value for
+   traffic engineering that is separate from the metric used for path
+   cost computation of the control plane.
+
+   Note that multiple "link metric values" could find use in optical
+   networks; however, it would be more useful to the RWA process to
+   assign these specific meanings such as "link mile" metric,
+   "probability of failure" metric, etc.
+
+6.6. Port Label Restrictions
+
+   Port label restrictions could be applied generally to any label types
+   in GMPLS by adding new kinds of restrictions.  Wavelength is a type
+   of label.
+
+   Port label (wavelength) restrictions (PortLabelRestriction) model the
+   label (wavelength) restrictions that the link and various optical
+   devices, such as Optical Cross-Connects (OXCs), ROADMs, and waveband
+   multiplexers, may impose on a port.  These restrictions tell us what
+   wavelength may or may not be used on a link and are relatively
+   static.  This plays an important role in fully characterizing a WSON
+   switching device [Switch].  Port wavelength restrictions are
+   specified relative to the port in general or to a specific
+   connectivity matrix (Section 4.1).  [Switch] gives an example where
+   both switch and fixed connectivity matrices are used and both types
+   of constraints occur on the same port.
+
+   <PortLabelRestriction> ::= <MatrixID>
+
+                              <RestrictionType>
+
+                              <Restriction parameters list>
+
+
+   <Restriction parameters list> ::=
+
+                        <Simple label restriction parameters> |
+
+                        <Channel count restriction parameters> |
+
+                        <Label range restriction parameters> |
+
+                        <Simple+channel restriction parameters> |
+
+                        <Exclusive label restriction parameters>
+
+
+
+Lee, et al.                   Informational                    [Page 15]
+
+RFC 7446                 WSON Information Model            February 2015
+
+
+   <Simple label restriction parameters> ::= <LabelSet> ...
+
+
+   <Channel count restriction parameters> ::= <MaxNumChannels>
+
+
+   <Label range restriction parameters> ::= <MaxLabelRange>
+
+                                            (<LabelSet> ...)
+
+
+   <Simple+channel restriction parameters> ::= <MaxNumChannels>
+
+                                               (<LabelSet> ...)
+
+
+   <Exclusive label restriction parameters> ::= <LabelSet> ...
+
+   Where
+
+   MatrixID is the ID of the corresponding connectivity matrix (Section
+   4.1).
+
+   The RestrictionType parameter is used to specify general port
+   restrictions and matrix-specific restrictions.  It can take the
+   following values and meanings:
+
+      SIMPLE_LABEL:   Simple label (wavelength) set restriction; the
+         LabelSet parameter is required.
+
+      CHANNEL_COUNT: The number of channels is restricted to be less
+         than or equal to the MaxNumChannels parameter (which is
+         required).
+
+      LABEL_RANGE:  Used to indicate a restriction on a range of labels
+         that can be switched.  For example, a waveband device with a
+         tunable center frequency and passband.  This constraint is
+         characterized by the MaxLabelRange parameter, which indicates
+         the maximum range of the labels, e.g., which may represent a
+         waveband in terms of channels.  Note that an additional
+         parameter can be used to indicate the overall tuning range.
+         Specific center frequency tuning information can be obtained
+         from information about the dynamic channel in use.  It is
+         assumed that both center frequency and bandwidth (Q) tuning can
+         be done without causing faults in existing signals.
+
+
+
+
+
+
+Lee, et al.                   Informational                    [Page 16]
+
+RFC 7446                 WSON Information Model            February 2015
+
+
+      SIMPLE LABEL and CHANNEL COUNT: In this case, the accompanying
+         label set and MaxNumChannels indicate labels permitted on the
+         port and the maximum number of labels that can be
+         simultaneously used on the port.
+
+      LINK LABEL_EXCLUSIVITY: A label (wavelength) can be used at most
+         once among a given set of ports.  The set of ports is specified
+         as a parameter to this constraint.
+
+   Restriction-specific parameters are used with one or more of the
+   previously listed restriction types.  The currently defined
+   parameters are:
+
+      LabelSet is a conceptual set of labels (wavelengths).
+
+      MaxNumChannels is the maximum number of channels that can be
+         simultaneously used (relative to either a port or a matrix).
+
+      LinkSet is a conceptual set of ports.
+
+   MaxLabelRange indicates the maximum range of the labels.  For
+   example, if the port is a "colored" drop port of a ROADM, then there
+   are two restrictions: (a) CHANNEL_COUNT, with MaxNumChannels = 1, and
+   (b) SIMPLE_WAVELENGTH, with the wavelength set consisting of a single
+   member corresponding to the frequency of the permitted wavelength.
+   See [Switch] for a complete waveband example.
+
+   This information model for port wavelength (label) restrictions is
+   fairly general in that it can be applied to ports that have label
+   restrictions only or to ports that are part of an asymmetric switch
+   and have label restrictions.  In addition, the types of label
+   restrictions that can be supported are extensible.
+
+6.6.1.  Port-Wavelength Exclusivity Example
+
+   Although there can be many different ROADM or switch architectures
+   that can lead to the constraint where a lambda (label) maybe used at
+   most once on a set of ports, Figure 3 shows a ROADM architecture
+   based on components known as Wavelength Selective Switches (WSSes)
+   [OFC08].  This ROADM is composed of splitters, combiners, and WSSes.
+   This ROADM has 11 output ports, which are numbered in the diagram.
+   Output ports 1-8 are known as drop ports and are intended to support
+   a single wavelength.  Drop ports 1-4 output from WSS 2, which is fed
+   from WSS 1 via a single fiber.  Due to this internal structure, a
+   constraint is placed on the output ports 1-4 that a lambda can be
+   used only once over the group of ports (assuming unicast and not
+   multicast operation).  The output ports 5-8 have a similar constraint
+   due to the internal structure.
+
+
+
+Lee, et al.                   Informational                    [Page 17]
+
+RFC 7446                 WSON Information Model            February 2015
+
+
+                            |               A
+                            v            10 |
+                        +-------+        +-------+
+                        | Split |        |WSS  6 |
+                        +-------+        +-------+
+     +----+              | | | |          | | | |
+     | W  |              | | | |          | | | +-------+   +----+
+     | S  |--------------+ | | |    +-----+ | +----+    |   | S  |
+   9 | S  |----------------|---|----|-------|------|----|---| p  |
+   --|    |----------------|---|----|-------|----+ |    +---| l  |<
+     | 5  |--------------+ |   |    | +-----+    | |     +--| i  |
+     +----+              | |   |    | |   +------|-|-----|--| t  |
+                +--------|-+   +----|-|---|------|----+  |  +----+
+     +----+     |        |          | |   |      | |  |  |
+     | S  |-----|--------|----------+ |   |      | |  |  |  +----+
+     | p  |-----|--------|------------|---|------|----|--|--| W  |
+   ->| l  |-----|-----+  | +----------+   |      | |  +--|--| S  |11
+     | i  |---+ |     |  | | +------------|------|-------|--| S  |->
+     | t  |   | |     |  | | |            |      | | +---|--|    |
+     +----+   | | +---|--|-|-|------------|------|-|-|---+  | 7  |
+              | | |   +--|-|-|--------+ | |      | | |      +----+
+              | | |      | | |        | | |      | | |
+             +------+   +------+     +------+   +------+
+             | WSS 1|   | Split|     | WSS 3|   | Split|
+             +--+---+   +--+---+     +--+---+   +--+---+
+                |          A            |          A
+                v          |            v          |
+             +-------+  +--+----+    +-------+  +--+----+
+             | WSS 2 |  | Comb. |    | WSS 4 |  | Comb. |
+             +-------+  +-------+    +-------+  +-------+
+             1|2|3|4|    A A A A     5|6|7|8|    A A A A
+              v v v v    | | | |      v v v v    | | | |
+
+   Figure 3: A ROADM Composed from Splitter, Combiners, and WSSes
+
+7.  Dynamic Components of the Information Model
+
+   In the previously presented information model, there are a limited
+   number of information elements that are dynamic, i.e., subject to
+   change with subsequent establishment and teardown of connections.
+   Depending on the protocol used to convey this overall information
+   model, it may be possible to send this dynamic information separately
+   from the relatively larger amount of static information needed to
+   characterize WSONs and their network elements.
+
+
+
+
+
+
+
+Lee, et al.                   Informational                    [Page 18]
+
+RFC 7446                 WSON Information Model            February 2015
+
+
+7.1.  Dynamic Link Information (General)
+
+   For WSON links, the wavelength availability and which wavelengths are
+   in use for shared backup purposes can be considered dynamic
+   information and hence are grouped with the dynamic information in the
+   following set:
+
+   <DynamicLinkInfo> ::=  <LinkID>
+
+                          <AvailableLabels>
+
+                          [<SharedBackupLabels>]
+
+   AvailableLabels is a set of labels (wavelengths) currently available
+   on the link.  Given this information and the port wavelength
+   restrictions, one can also determine which wavelengths are currently
+   in use.  This parameter could potentially be used with other
+   technologies that GMPLS currently covers or may cover in the future.
+
+   SharedBackupLabels is a set of labels (wavelengths) currently used
+   for shared backup protection on the link.  An example usage of this
+   information in a WSON setting is given in [Shared].  This parameter
+   could potentially be used with other technologies that GMPLS
+   currently covers or may cover in the future.
+
+   Note that the above does not dictate a particular encoding or
+   placement for available label information.  In some routing
+   protocols, it may be advantageous or required to place this
+   information within another information element such as the Interface
+   Switching Capability Descriptor (ISCD).  Consult the extensions that
+   are specific to each routing protocol for details of placement of
+   information elements.
+
+7.2.  Dynamic Node Information (WSON Specific)
+
+   Currently the only node information that can be considered dynamic is
+   the resource pool state, and it can be isolated into a dynamic node
+   information element as follows:
+
+   <DynamicNodeInfo> ::=  <NodeID> [<ResourcePool>]
+
+8.  Security Considerations
+
+   This document discusses an information model for RWA computation in
+   WSONs.  From a security standpoint, such a model is very similar to
+   the information that can be currently conveyed via GMPLS routing
+   protocols.  Such information includes network topology, link state
+   and current utilization, as well as the capabilities of switches and
+
+
+
+Lee, et al.                   Informational                    [Page 19]
+
+RFC 7446                 WSON Information Model            February 2015
+
+
+   routers within the network.  As such, this information should be
+   protected from disclosure to unintended recipients.  In addition, the
+   intentional modification of this information can significantly affect
+   network operations, particularly due to the large capacity of the
+   optical infrastructure to be controlled.  A general discussion on
+   security in GMPLS networks can be found in [RFC5920].
+
+9.  References
+
+9.1.  Normative References
+
+   [G.7715]  ITU-T, "Architecture and requirements for routing in the
+             automatically switched optical networks", ITU-T
+             Recommendation G.7715, June 2002.
+
+   [RBNF]    Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax Used
+             to Form Encoding Rules in Various Routing Protocol
+             Specifications", RFC 5511, April 2009,
+             <http://www.rfc-editor.org/info/rfc5511>.
+
+   [RFC3471] Berger, L., Ed., "Generalized Multi-Protocol Label
+             Switching (GMPLS) Signaling Functional Description", RFC
+             3471, January 2003,
+             <http://www.rfc-editor.org/info/rfc3471>.
+
+   [RFC3630] van der Meer, J., Mackie, D., Swaminathan, V., Singer, D.,
+             and P. Gentric, "RTP Payload Format for Transport of MPEG-4
+             Elementary Streams", RFC 3640, November 2003,
+             <http://www.rfc-editor.org/info/rfc3640>.
+
+   [RFC4202] Kompella, K., Ed., and Y. Rekhter, Ed., "Routing Extensions
+             in Support of Generalized Multi-Protocol Label Switching
+             (GMPLS)", RFC 4202, October 2005,
+             <http://www.rfc-editor.org/info/rfc4202>.
+
+   [RFC4203] Kompella, K., Ed., and Y. Rekhter, Ed., "OSPF Extensions in
+             Support of Generalized Multi-Protocol Label Switching
+             (GMPLS)", RFC 4203, October 2005,
+             <http://www.rfc-editor.org/info/rfc4203>.
+
+   [RFC4328] Papadimitriou, D., Ed., "Generalized Multi-Protocol Label
+             Switching (GMPLS) Signaling Extensions for G.709 Optical
+             Transport Networks Control", RFC 4328, January 2006,
+             <http://www.rfc-editor.org/info/rfc4328>.
+
+   [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
+             Engineering", RFC 5305, October 2008,
+             <http://www.rfc-editor.org/info/rfc5305>.
+
+
+
+Lee, et al.                   Informational                    [Page 20]
+
+RFC 7446                 WSON Information Model            February 2015
+
+
+   [RFC5307] Kompella, K., Ed., and Y. Rekhter, Ed., "IS-IS Extensions
+             in Support of Generalized Multi-Protocol Label Switching
+             (GMPLS)", RFC 5307, October 2008,
+             <http://www.rfc-editor.org/info/rfc5307>.
+
+   [RFC6163] Lee, Y., Ed., Bernstein, G., Ed., and W. Imajuku,
+             "Framework for GMPLS and Path Computation Element (PCE)
+             Control of Wavelength Switched Optical Networks (WSONs)",
+             RFC 6163, April 2011,
+             <http://www.rfc-editor.org/info/rfc6163>.
+
+   [RFC7308] Osborne, E., "Extended Administrative Groups in MPLS
+             Traffic Engineering (MPLS-TE)", RFC 7308, July 2014,
+             <http://www.rfc-editor.org/info/rfc7308>.
+
+9.2.  Informative References
+
+   [OFC08]   Roorda, P., and B. Collings, "Evolution to Colorless and
+             Directionless ROADM Architectures", Optical Fiber
+             Communication / National Fiber Optic Engineers Conference
+             (OFC/NFOEC), 2008, pp. 1-3.
+
+   [RFC5920] Fang, L., Ed., "Security Framework for MPLS and GMPLS
+             Networks", RFC 5920, July 2010,
+             <http://www.rfc-editor.org/info/rfc5920>.
+
+   [Shared]  Bernstein, G., and Y. Lee, "Shared Backup Mesh Protection
+             in PCE-based WSON Networks", iPOP 2008.
+
+   [Switch]  Bernstein, G., Lee, Y., Gavler, A., and J. Martensson,
+             "Modeling WDM Wavelength Switching Systems for Use in GMPLS
+             and Automated Path Computation", Journal of Optical
+             Communications and Networking, vol. 1, June 2009, pp.
+             187-195.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Lee, et al.                   Informational                    [Page 21]
+
+RFC 7446                 WSON Information Model            February 2015
+
+
+Contributors
+
+   Diego Caviglia
+   Ericsson
+   Via A. Negrone 1/A 16153
+   Genoa, Italy
+
+   Phone: +39 010 600 3736
+   EMail: diego.caviglia@(marconi.com, ericsson.com)
+
+
+   Anders Gavler
+   Acreo AB
+   Electrum 236
+   SE - 164 40 Kista
+   Sweden
+
+   EMail: Anders.Gavler@acreo.se
+
+
+   Jonas Martensson
+   Acreo AB
+   Electrum 236
+   SE - 164 40 Kista
+   Sweden
+
+   EMail: Jonas.Martensson@acreo.se
+
+
+   Itaru Nishioka
+   NEC Corp.
+   1753 Simonumabe, Nakahara-ku, Kawasaki, Kanagawa 211-8666
+   Japan
+
+   Phone: +81 44 396 3287
+   EMail: i-nishioka@cb.jp.nec.com
+
+
+   Lyndon Ong
+   Ciena
+   EMail: lyong@ciena.com
+
+
+   Cyril Margaria
+   EMail: cyril.margaria@gmail.com
+
+
+
+
+
+
+Lee, et al.                   Informational                    [Page 22]
+
+RFC 7446                 WSON Information Model            February 2015
+
+
+Authors' Addresses
+
+   Young Lee (editor)
+   Huawei Technologies
+   5369 Legacy Drive, Building 3
+   Plano, TX  75023
+   United States
+
+   Phone: (469) 277-5838
+   EMail: leeyoung@huawei.com
+
+
+   Greg M. Bernstein (editor)
+   Grotto Networking
+   Fremont, CA
+   United States
+
+   Phone: (510) 573-2237
+   EMail: gregb@grotto-networking.com
+
+
+   Dan Li
+   Huawei Technologies Co., Ltd.
+   F3-5-B R&D Center, Huawei Base,
+   Bantian, Longgang District
+   Shenzhen 518129
+   China
+
+   Phone: +86-755-28973237
+   EMail: danli@huawei.com
+
+
+   Wataru Imajuku
+   NTT Network Innovation Labs
+   1-1 Hikari-no-oka, Yokosuka, Kanagawa
+   Japan
+
+   Phone: +81-(46) 859-4315
+   EMail: imajuku.wataru@lab.ntt.co.jp
+
+
+
+
+
+
+
+
+
+
+
+
+Lee, et al.                   Informational                    [Page 23]
+