Abstract:
Due to demand for more network bandwidth, a need for multi-user optical network topologies has, and will continue to, increase. A method or corresponding apparatus in embodiments of the present invention provide for an availability determination tool for determining and displaying wavelength and subrate availabilities within a network. Benefits of embodiments of a tool include allowing a user to identify the availability and capacity of any wavelength on any network, via an interactive graphical user interface, such as by using three-dimensional representations. In one embodiment, the disclosed availability determination tool allows users to locate and view any combination of available wavelengths between nodes in an optical network topology, and generate graphical and tabular reports of the availability in order to maintain an efficient and organized method or apparatus for determining and controlling wavelengths in a network. Consequently, service providers using the tool can keep performance rates high and costs low.

Description:
RELATED APPLICATIONS 
       [0001]    This application is related to U.S. application Ser. No. 11/354,705, filed on Feb. 14, 2006; and Attorney Docket Nos. 2376.2253-000, entitled “Method and Apparatus for Designing Any-To-Any Optical-Signal-to-Noise Ratio in Optical Networks;” 2376.2254-000, entitled “Method and Apparatus for Reducing Cost of an Optical Network Amplification in a Network;” and 2376.2263-000, entitled “Method and Apparatus for Simplifying Planning and Tracking of Multiple Installation Configurations;” each of which is being filed concurrently. The entire teachings of the above applications are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Wavelength Division Multiplexing (WDM) is a method by which optical fibers are used to carry multiple light waves of different frequencies. In a WDM network many wavelengths are combined in a single fiber, thereby increasing the carrying capacity of the fiber. Signals are assigned to specific frequencies of light (wavelengths) within a frequency band. This multiplexing of optical wavelengths is analogous to the way radio stations broadcast on different wavelengths as to not interfere with each other. Because each radio channel is transmitted on a different wavelength, a desired channel may be selected using a tuner. WDM channels (wavelengths) are selected in a similar manner. In a WDM network, all wavelengths are transmitted through a fiber, and demultiplexed at a receiving end. The fiber&#39;s capacity is an aggregate of the transmitted wavelengths, each wavelength having its own dedicated bandwidth. Dense Wavelength Division Multiplexing (DWDM) is a WDM network in which wavelengths are spaced more closely than in a coarse WDM network. This provides for a greater overall capacity of the fiber. 
         [0003]    Modern networks use WDM, including coarse WDM (CWDM) and dense WDM (DWDM), to increase the amount of traffic that can be transmitted through the network. WDM signals may propagate through optical networks, in both clockwise and counterclockwise directions, connecting each node pair via two paths. Alternatively, WDM signals may propagate through the network in only one direction, limiting each node pair to a single connection path. 
         [0004]    Many WDM networks use Reconfigurable Optical Add/Drop Multiplexers (ROADMs) to add or drop traffic to or from the network. Selected wavelengths can be added or dropped using the ROADMs by issuing commands from a central Network Management System (NMS). Typically, a ROADM deployment scenario exists where bandwidth needs to be deployed between two locations. Normally, a service provider installs transponders at the locations, balances the power across each span, and starts using the service. This basic approach is much simpler when the network is first installed and an abundance of wavelengths is available. As more connections over the network are created, however, more wavelengths will be needed because, for a given connection, the same wavelength typically needs to be available on every span of the path supporting the connection over the network. Further, if the service provider is planning a resilient service, it must ensure that two contiguous wavelengths are available between each start and end point of each communications path. If a contiguous wavelength between the two locations is not available, then an optical connection between the locations typically may not be established. 
       SUMMARY OF THE INVENTION 
       [0005]    One example embodiment of the present invention is a method, and corresponding apparatus, for determining whether a wavelength is available in an optical network topology. The method may display representations of nodes and physical links of the topology. The method may further enable selection of the representations of the physical links to form a path through the topology. Once the path is selected, the method determines wavelength availability along the path and reports the wavelength availability of at least a subset of the wavelengths along the path. 
         [0006]    A second example embodiment of the present invention is a method, and corresponding apparatus, for determining whether a wavelength is available in an optical network topology. The method may similarly display representations of nodes and physical links of the topology. The method may further enable selection of at least two nodes of the optical network topology to determine paths connecting the selected nodes through the topology. Once the paths are determined, the method determines wavelength availability along the paths and reports the available paths connecting the nodes, along with the wavelength availability along the paths. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The foregoing will be apparent from the following more particular description of example embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating embodiments of the present invention. 
           [0008]      FIG. 1  is a diagram of a user viewing an optical network topology on an availability determination tool for the purpose of determining wavelength availability in an optical network using an example embodiment of the present invention. 
           [0009]      FIG. 2  is a diagram of a user viewing a three-dimensional rendering and a graphical user interface of an availability determination tool for the purpose of knowing wavelength availability in an optical network using an example embodiment of the present invention. 
           [0010]      FIG. 3  is a schematic diagram of an example topology, representing one working wavelength and one protection wavelength that connect two nodes in a network. 
           [0011]      FIG. 4  is a schematic diagram of a fiber-optic link enlarged to show examples of different wavelengths that can exist on a single link in a network. 
           [0012]      FIG. 5  is network diagram showing a display of wavelength availability along with representations of nodes and physical links of the topology, according to an example embodiment of the present invention. 
           [0013]      FIG. 6  is a block diagram of multiple nodes of the topology illustrating wavelength interchange along two wavelengths in an example embodiment of the present invention. 
           [0014]      FIG. 7A  is an example interface available to a user to enable selection of at least two nodes of a topology. 
           [0015]      FIG. 7B  is an example graphical user interface enabling selection of at least two nodes of the topology and highlighting said nodes. 
           [0016]      FIG. 8A  is an example table reporting wavelength of the wavelengths along a path. 
           [0017]      FIG. 8B  is a graph displaying the wavelength and subrate availability on the topology in graphical format in an example embodiment of the present invention. 
           [0018]      FIGS. 9A and 9B  are schematic diagrams displaying representations of nodes and physical links of a topology in a base plane of a three-dimensional view, where the available wavelengths are represented in respective planes elevated above the base plane according to an example embodiment of the present invention. 
           [0019]      FIGS. 10 ,  11 ,  12 , and  13  are flow diagrams representative of example methods of providing wavelength availability in an optical network topology. 
           [0020]      FIGS. 14 ,  15 ,  16 , and  17  are block diagrams of an apparatus to provide wavelength availability in an optical network topology. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    A description of example embodiments of the invention follows. 
         [0022]    Example embodiments of the present invention enable users, such as network providers, to visualize, choose, and display wavelength utilization across an optical network topology for a network designer to provision wavelengths in a ring, mesh, RPR (packet), or network unprotected environment. According to the embodiments, a network designer has the freedom to route wavelengths from any node to any other node within the network; thus allowing for some wavelengths to be organized in rings over a set of fiber links, while other wavelengths can be organized on some, but not all, of the same links (paths). 
         [0023]    In some optical networks, wavelengths are not tied to a particular topology, which means that a network designer must have knowledge as to what wavelengths and, in some cases, subrates are available if choosing to activate a wavelength within the topology. Typically, in example embodiments, availability refers to unallocated paths through the network that can support traffic demands with or without the addition of cards within one or a set of network elements (not including the addition of more network elements). If the network designer activates a wavelength on a path of the topology that is already provisioned on that path, faults occur, as understood in the art. Embodiments of the present invention enable the network designer to determine what wavelengths are available over what paths and provides the network designer with interactive feedback on how the wavelengths can be assigned to the paths. Further, some embodiments of this invention display wavelength usage across the entire network, including any or all sub-networks, and an interactive approach is provided to aid network designers in finding an available path or multiple available paths throughout the network. 
         [0024]    Further, embodiments may include an availability determination tool that can include a method or apparatus for selecting two nodes on a graphical representation of the network and listing the possible existing paths through the network with a listing of the available bandwidth on those paths. The availability determination tool may be a stand alone utility, or may be a feature of a larger network planning tool. Also included in an embodiment of this invention is a tool that displays and reports possible routes for new wavelengths that can be defined to carry those demands. 
         [0025]    An example embodiment of the present invention allows a network designer (i.e., user) to determine the available wavelengths that connect two points (e.g., nodes in the network) and determines an amount of traffic that the wavelengths can carry throughout. By displaying this information to a user, the user may view the graphical interface to enable the user to select multiple links and be informed of available wavelengths that span those links. The user can also select end (i.e., destination) nodes, and the graphical interface system informs the user of common rings already existing and what wavelengths are available between the end nodes. 
         [0026]    Some embodiments of the present invention can include determinations and displays of representations of nodes in an optical network topology, where the nodes can include representations of ROADMs, which allow traffic to be added to wavelengths at one node and removed (demultiplexed) from a wavelength at another node. The availability determination tool, according to some example embodiments of the present invention, can determine alternative paths that traffic may take if certain wavelengths are full or cannot maintain the amount of traffic. The tool can use wavelength interchange, which allows information traveling on one wavelength to be transferred to another wavelength via an interchange converter. By enabling traffic to be transmitted via multiple different wavelengths, embodiments of the present invention can reroute wavelengths to change the wavelength availability that is available for use by a network designer. 
         [0027]    Some embodiments of the present invention can determine if a wavelength is available and report the information to the user using a plurality of different methods, including a graphical user interface that renders three-dimensional interpretations of the representations of nodes and physical links of an optical network topology. Other embodiments of the present invention include a graphical user interface, which can enable the user to view the wavelength availability information in a tabular form and allow the user to highlight, or the tool can automatically highlight, the wavelength availability in the tabular form. Some embodiments of the present invention include a display of the optical network topology in a three-dimensional view that can allow the user to view the representations of nodes, physical links, wavelength availability, and paths through the network. 
         [0028]      FIG. 1  is a diagram of a user  180  using an availability determination tool  100  to determine and view wavelength availability and subrate availability in an optical ring network  131  according to an example embodiment of the availability determination tool  100 . In an example embodiment of the present invention, the user  180  can use the tool  100  to view the available elements of the optical network  131 , such as the paths or nodes of the optical network  131 , via a user interface  121 , such as a workstation  111 . As understood in the art, typical characteristics of an optical network include the network topology, the number and distribution of nodes, and the number, distribution, and type of optical network elements. Next, the user  180  can choose among a plurality of input options, including a system prompt input method  141  or a graphical user interface  151  to choose the paths or nodes for which the user  180  requests the availability determination tool  100  to determine available wavelengths. After the user  180  selects the desired network elements necessary for the availability determination tool  100  to determine wavelength availability and subrate availability, the tool  100  runs internal iterations. 
         [0029]      FIG. 2  is a diagram of a user  280  viewing a three-dimensional rendering and a graphical user interface of an availability determination tool  200  after the internal iterations run, for the purpose of knowing wavelength availability in an optical network using an example embodiment of the present invention. Once the availability determination tool  200  completes the internal iterations, optionally using traditional or proprietary algorithms, the tool  200  reports indications of wavelength and subrate availability to the user  280  via a display, such as a graphical user interface  221 . Such displays may include a plurality of three-dimensional views  271  and  281  of the optical network topology, including the nodes, fiber-optical links, a base plane, a series of paths connecting the nodes in sub-networks, and the available wavelengths in respective planes above the base plane. The availability determination tool  200  displays results to the user  280  in any of a plurality of views, including a tabular view  251  or a graphical view  261 , so that the user  280  can plan accordingly with regards to the available wavelengths on any given optical network topology. 
         [0030]      FIG. 3  is a schematic diagram that illustrates an optical network topology  300  including a plurality of nodes  310   a - f  connected via a plurality of fiber optic links  315   a - f.  For example, node  310   a  connects to node  310   b  via a first fiber optic link  315   a  in a clockwise direction  302 . A working wavelength  305   a  travels in one direction, and a protection wavelength  305   b  travels in the opposite direction. The working wavelength  305   a  typically takes a shorter path between the two nodes  310   a - b,  and the protection wavelength  305   b  takes a longer path. The frequency of the working and protection wavelengths may be identical, as they travel in opposite directions. 
         [0031]    Typically, nodes may include or may be located at central offices (not shown), communications sites, communications devices, etc. The topology  300  shown in  FIG. 3  is an example embodiment of a ring topology, whereas other networks and sub-networks may have other topologies including, but not limited to, linear, mesh, unidirectional, bidirectional, or hybrid topologies. Additionally, networks may have any number of nodes and fiber optic links, and those links may include more than one fiber optic link. The example methods and apparatuses disclosed herein may be used to at least determine or display wavelength availabilities, or subrate availabilities, or any combination thereof, on the network with any suitable topology, any number of nodes, and any number of fiber optic links. 
         [0032]      FIG. 4  is a schematic diagram illustrating an expanded view of a fiber-optic cable to show separate wavelengths  400  that includes a pluraility of different wavelengths  405   a - f  coursing through the cable. A fiber-optic link  415 , in this example embodiment of the present invention, connects node  410   a  to node  410   b,  and traffic can be transmitted from node  410   a  to node  410   b  (or vice versa) via any of the available wavelengths  405   a - f  carried inside the fiber-optic link  415 . 
         [0033]    In an example embodiment of the present invention,  FIG. 4  represents a node-to-node WDM system, in which several wavelengths  405   a - f  are multiplexed at one node  410   a,  the node  410   a  transmits the combined signals across some distance of the link  415  on the different wavelengths  405   a - f  that are included in the link  415 . The wavelengths  405   a - f  are then demultiplexed at a destination node  410   b,  which may be automatically chosen by the system or may be specifically chosen by a user. In order to enable the user to have knowledge of what wavelengths  405   a - f  are available to carry a signal from a selected or automated starting point (e.g., node  410   a ) to a selected or automated destination point (e.g., node  410   b ), the user may be supplied with information in a tabular, graphical, pictorial, three-dimensional, or some other suitable visual display on a user interface. 
         [0034]      FIG. 5  is a schematic diagram illustrating an optical network topology  500 , which includes multiple ring networks that can be represented to a user of an example embodiment of the availability determination tool. The sub-networks send can signals via different wavelengths to and from the different nodes  500   a - r  located on the different sub-networks  502   a - c,  on a network  501 . As previously mentioned, there are many types of networks available, and this example embodiment of a ring network is not meant to limit the network configurations to which the availability determination tool can be applied. 
         [0035]      FIG. 6  is a schematic diagram illustrating wavelength conversion. Wavelength conversion (interchange) in WMD networks has been proposed to improve efficiency within the network without having to add more fiber-optic links (or other hardware). In some instances, traffic may not be able to be transmitted over a single wavelength for any plurality of reasons. Therefore, in order to transmit the traffic, an embodiment of the present invention allows for a user to choose the nodes that the user wishes traffic to travel to and from, and the example embodiment locates the available paths and the available wavelengths on those paths. 
         [0036]    Assuming, only for purposes of this example embodiment of the present invention, the user wants to transmit traffic from node  610   a  to node  610   d,  but the example embodiment of the present invention cannot detect any available wavelengths to transmit the entirety of the traffic. This embodiment of the availability determination tool locates different wavelengths that are available to handle the amount of traffic to be transmitted, and then, using a process called wavelength conversion (interchange), allows the traffic to start on a first wavelength  605   a,  then be converted by a wavelength converter  655   a  so the traffic can then travel on a second wavelength  605   b.  In this example embodiment, the traffic must enter a second wavelength converter  655   b  in order to travel back onto the first wavelength  605   a  before the traffic can reach the user&#39;s chosen destination, e.g., node  610   d.    
         [0037]      FIG. 7A  illustrates an example embodiment of a user interface according to an example embodiment of the present invention. A user may be prompted, or may request from the availability determination tool, the ability to select at least two nodes of the topology in order for the system to determine what available paths exist between the chosen nodes, and display the findings to the user in either a tabular or graphical format described in more detail below. The tool may prompt the user by displaying a direction or questions  775   a  to input the name or number (or some other identifier) of a node, into an input box  785   a  using some method of input known in the art, e.g., a computer keyboard, touch screen technology, voice recognition, or any other suitable input method. The manner in which the tool prompts the user may consist of traditional or proprietary algorithms or user interfaces, or any combination thereof. After the user enters the selection into input box  785   a,  the user can then accept the information by pressing an accept button  795   a.  This action is communicated with the tool, and the user is next prompted  775   b  to input at least a second node of the topology into the input box  785   b  and again accept the information by pressing the accept button  795   b.  If the user wants to enter more nodes than at least two, as offered in an embodiment of the present invention, the user may press the additional nodes button  796   a,  and the tool again continues prompting the user to enter node identifiers until the user chooses to accept the nodes previously entered, the user has identified all nodes on the topology, or some additional action occurs within the tool, or to the tool, to end the input stage. 
         [0038]    Once the user concludes entering and answering input for the tool, the user may press an accept button  795   c  in order to allow the tool to run an algorithm internally to locate, determine, and display available paths between chosen nodes and the available wavelengths and subrate availabilities of those paths in order to be shown to the user, as described in more detail below. The internal algorithms may consist of traditional or proprietary algorithms, or any combination thereof. 
         [0039]      FIG. 7B  illustrates an alternative embodiment of the present invention, which allows a user  780  to select at least two nodes from any of the nodes  710   a - f  connected by the fiber optic links  715   a - f  on an optical network topology  700 B, via a graphical user interface. Similarly to the process described above for  FIG. 7A , the user  780  may be prompted, or may request from the availability determination tool the ability to select at least two nodes  710   a - f  of the topology  700 B in order for the tool to determine what available paths exist between the chosen nodes, and display the findings to the user  780  in either a tabular or graphical format, described in more detail below. The user  780  may be prompted  775   d  by the tool to choose the name or number (or some other suitable identifier) of a node, using some method of input known in the art, e.g., a computer keyboard, touch screen technology, voice recognition, mouse, pointing, algorithm, or some other suitable method for inputting information. After the user  780  selects one of the two nodes from nodes  710   a - f  available on this example embodiment of the network, this action can be communicated with the tool, and the user  780  is next prompted  775   e  to select at least a second node  715   a - f  of the topology using a similar method of selection as described above. If the user  780  wants to enter more nodes  710   a - f  than the two, as offered in this embodiment of the present invention, the user  780  can press the additional nodes button  796   b  and the tool again continues prompting the user  780  to select node  715   a - f  identifiers until the user  780  chooses to accept the nodes previously selected, the user  780  has identified all nodes on the topology  700 B, or some additional action occurs within the tool, or to the tool, which ends the selection stage. 
         [0040]    Once the user  780  concludes selecting and answering input for the tool, the user  780  can press an accept button  795   d  and allows the tool to run an algorithm internally, or other type of program, that locates, determines, or displays available paths between chosen nodes  710   a - f,  and can further include finding or displaying the wavelength availability and subrate availability of those paths  715   a - f,  in order to be shown to the user  780  as described in more detail below. 
         [0041]      FIG. 8A  illustrates an example of a tabular display  801   a  of information on available wavelengths of the topology, where a user  880  requested or selected information on five wavelengths  810   a - e.    
         [0042]    In an embodiment of the present invention, in order for the user  880  to read the table  801   a,  the user  880  can start at a wavelength identifier row, then move down to the row labeled Wavelength (nm)  820  and read entries listed to the right of that row; these entries denote the available wavelengths  820   a - e  in nanometers for the specified wavelength identifiers  810   a - e.  Some embodiments of the present invention may allow the table  801   a  to further include information on subrate availability  845 , which informs the user  880  on how much capacity  845   a - e  may be available on a specified wavelength. Typically, availability will include at least unallocated paths through the network that can support traffic demands. An example embodiment of the present invention illustrates that the table  801   a  may include a plurality of buttons  895   a - e  that allow the user  880  to perform a multitude of different tasks associated with this embodiment of the present invention. 
         [0043]      FIG. 8B  illustrates the same information as  FIG. 8A , but in a graphical representation of an example embodiment of the present invention. Some example embodiments of a graphical view  801   b  allow a user  880  to visualize the wavelength availabilities and the subrate availabilities of those wavelengths in a three-dimensional view. These capabilities of the example embodiment of the present invention are advantageous for a plurality of reasons, including, but not limited to, the possibility that different users may have diverse styles of understanding information, e.g., converging, accommodating, assimilating, diverging, auditory, visual, or tactile, and the ability of an embodiment of the present invention to provide multiple varieties of information display, as opposed to a more simplistic model of information output that may exist, is advantageous. 
         [0044]      FIGS. 9A-9B  are example embodiments of three-dimensional (3-D) visualizations  970  of the present invention&#39;s display module  912  for a user  980  to monitor the available wavelengths  905   a - c,  along with the representations of nodes  910   a - j  and physical links  915   a - j,  as part of a 3-D view in respective planes elevated above a base plane  971 . 
         [0045]      FIG. 9A  is an embodiment of the present invention&#39;s display module  912 A exemplifying a plurality of sub-networks in a 3-D model. The display module  912 A displays the representation of nodes and physical links in the base plane  971  of a 3-D view  970 . The base plane  971 , in this embodiment, consists of nodes  910   a - y  and physical links attaching those nodes  910   a - y.  In the 3-D view  970 , the display module  912  displays the available wavelengths in respective planes elevated above the base plane  971 . In this embodiment of the present invention, the system groups available wavelengths into sections and provided a visual display of all of the available wavelengths on a given sub-network  906   a - e.  Each level of wavelengths shown in each of the respective sub-networks  906   a - e  represents a 3-D view  970  of the available wavelengths in respective planes. 
         [0046]    In  FIG. 9A  assume, for this example embodiment of the present invention only, that the user  980  previously requested that the system determines all of the available wavelengths on specified sub-networks. In order to receive the 3-D model in  FIG. 9A , the user  980  may have requested sub-networks including the following groupings of nodes:
       The first sub-network  908   a  contains nodes  910   b,    910   c,    910   d,  and  910   y.      The second sub-network  908   b  contains nodes  910   p,    910   r,    910   v,    910   w,  and  910   x.      The third sub-network  908   c  contains nodes  910   q,    910   s,    910   t,  and  910   u.      The fourth sub-network  908   d  contains nodes  910   e,    910   g,    910   h,    910   l,    910   m,    910   o,    910   p,  and  910   x.      The fifth sub-network  908   e  contains nodes  910   h,    910   i,  and  910   k.  
 
In this embodiment, the display module  912 A displays all of the available wavelengths as part of a 3-D view in respective planes elevated above the base plane  971 ; this embodiment further displays the wavelength availability along with the representation of nodes  910   a - y  and physical links. Some embodiments of the present invention allow the user  980  to modify the display module  912  to allow for customizable graphics and pictorial 3-D views, which could include different angles, colors, sizes, or any other suitable graphical user interface changes.
       
 
         [0052]    In  FIG. 9B  assume, for this example embodiment of the present invention only, that the user  980  previously requested that the availability determination tool determines a path between two selected nodes,  910   h  and  910   a.  The tool, via the determination module (discussed below in detail) determines the wavelength availability and displays the topology in a 3-D view. The user  980  can read the 3-D representation of nodes  910   a - j  and physical links  915   a - j,  as displayed in the base plane  971  of the 3-D view  970 , by starting at node  910   h  and following a path  925  the tool determines. The path  925  uses λ 2   905   b  to traverse across three sub-networks within a network  900 B by starting at node  910   h,  following the path to node  910   i,  then to node  910   j,  then to node  910   f,  then over a different sub-network to node  910   c,  then to node  910   d,  then to node  910   e,  and stopping at the destination node, e.g., node  910   a.  Hence, in this example embodiment of the present invention, the tool finds the path  925  with an available wavelength  905   b  from node  910   h  to node  910   a  and then displays all of these elements to the user  980  in the 3-D view  970 . In this example embodiment, the display module  912  displays the 3-D view  970  of the topology  900 B above the base plane  971  of the 3-D view  970 . The display module  912  further displays the available wavelengths  905   a - c  as part of the 3-D view  970  in respective planes elevated above the base plane  970 . 
         [0053]    In some embodiments of the present invention, the user  980  can rotate, spin, change, or otherwise manipulate the display module  912  to change the directionality of the 3-D view  970 . In some embodiments, the 3-D view  970  can be customizable according to the user&#39;s  980  preferences or capabilities; such as, different graphical user interfaces, viewing capabilities, or other such differences in the art that can affect the    3   -D view  970 . 
         [0054]      FIG. 10  is a flow chart that illustrates an example method for displaying and identifying available wavelengths across a topology  1000  according to the disclosed availability determination tool. Wavelength determination begins with the user accessing a display module  1010 , which displays representations of nodes and physical links of the topology. A representation of nodes and physical links of the topology could be a graphic image displayed to the user via any suitable graphical user interface. 
         [0055]    After the user accesses the display module, an example embodiment of the present invention prepares an enabling module  1020 , which enables selection of the representation of the physical links to form a path through the topology. In some embodiments, the enabling module  1020  can display to the user a tabular, graphical, pictorial format, or a combination of these formats, in order for the user to select a specific path, or multiple paths. Next, the availability determination tool accesses, or allows the user to access, a determination module  1030 . The determination module  1030  determines the wavelength availability along the user specified paths selected, through the enabling module  1020 . 
         [0056]    After the determination module  1030  establishes the wavelength availability along specified paths, the availability determination tool accesses, or allows the user to access, a reporting module  1040 . The reporting module  1040  reports the wavelength availability of at least a subset of the wavelengths along the specified paths. The reporting module  1040  can display to the user a tabular, graphical, pictorial format, or a combination of these formats, in order for the user to visualize or receive reports of wavelength availability. 
         [0057]      FIG. 11  is a flow chart that illustrates a second example method of the present invention, which displays and identifies available wavelengths across a topology  1100 , according to the disclosed availability determination tool. As in the example embodiment illustrated in  FIG. 10 , determination begins with accessing a display module  1112 , the display module discloses a representation of nodes and physical links of the topology. The network topology may be a ring, mesh, hybrid ring/mesh, RPR (packet), or any other suitable topology. The network topology may contain multiple network elements that can include a representation of nodes, a representation of physical links, a plurality of paths, and other elements used in the provisioning of topology services. The physical links form a path  1125  through the topology connecting a plurality of nodes  1105  on the network. The path  1125  created by the physical links can include at least two forms, a protected path  1126  or an unprotected path  1127 . 
         [0058]    The nodes  1105  existing of the topology can be reconfigurable; that is, the nodes  1105  can be used to selectively reconfigure the optical interconnections associated with the network paths. This reconfiguration may be in the optical domain and may be achieved through the use of ROADMs  1135 . Additionally, the nodes  1105  of the network may include add/drop ports that are used for adding or dropping wavelengths to and from the network. This example embodiment of a method of the present invention allows the user to view the displayed topology, which can include any or all of the above mentioned network elements. 
         [0059]    Next, the system accesses, or allows a user  1180  to access, an enabling module  1120  in order for the user  1180  to select the physical links of the topology, via a suitable form of input. Once the user  1180  makes a selection, the availability determination tool accesses a determination module  1130 . The determination module  1130  determines wavelength availability along the selected paths  1125 . The determination module  1130  can further determine the subrate availability  1145  of a wavelength; this information enables the user  1180  to know if a wavelength is being used to its full capacity, or if the wavelength is only being partially used and may be able to transmit more traffic to or from different nodes. The determination module  1130  can further determine alternative paths  1125  using wavelength interchange  1150  to reroute wavelengths to change the wavelength availability. In some embodiments of the present invention, the user  1180  can use the availability determination tool to find a path  1125  from one node  1105  to another node  1105  that must use one or more wavelengths. The wavelength interchange  1150  determines the different wavelengths within a particular network or sub-network necessary to transmit the traffic to the selected destination. 
         [0060]    The user  1180  can then use the availability determination tool to view the information in a reporting module  1140 . The reporting module  1140  reports the wavelength availability and the subrate availability  1155  by further configuring the display module  1112  to display the representation of nodes and physical links  1165  in a base plane  1170  of a three-dimensional view  1160 . In an example embodiment of the present invention, the tool enables user  1180  to view a display of the wavelength availability, along with the topology in the three-dimensional view. Where the available wavelengths display in respective planes elevated above the base plane  1170 . 
         [0061]    In some embodiments, the reporting module  1140  can include elements such as the representations of physical links of the topology, selections thereof, the wavelength availability, or any other suitable elements that the system can report to the user  1180 . The reporting module  1140  can further allow the user  1180  to view the elements of the reporting module  1140  in a tabular format and highlight the wavelength availability  1175 . In some embodiments, the user  1180  can view the elements of the reporting module  1140  in a pictorial, graphical, tabular format, any combination thereof, or any suitable format to view information. 
         [0062]      FIG. 12  is a flow chart that illustrates a third example embodiment of a method of the present invention that displays and identifies available wavelengths across a topology  1200 , according to the disclosed availability determination tool. Wavelength determination begins where the user accesses a display module  1212  that displays representations of nodes and physical links of the topology  1200 . A representation of nodes and physical links of the topology  1200  can include a graphic image displayed to the user via any suitable graphical user interface. 
         [0063]    After the user accesses the display module, an example embodiment of the present invention prepares an enabling module  1220  that enables selection of at least two nodes of the topology  1200 . In some embodiments, the enabling module  1220  can display to the user a tabular, graphical, pictorial format, or a combination of these formats, in order for the user to select a specific path, or multiple paths. Next, the availability determination tool accesses, or allows the user to access, a determination module  1230 . The determination module  1230  determines paths connecting at least two nodes of the topology  1200 , selected by the user; this module  1230  further determines wavelength availability along the paths. In an example embodiment, the determination module  1230  allows the system to consider any or all of the possible wavelengths that are connected to the specified nodes, and then determines the availability of each of those wavelengths in order to determine for the user which wavelengths are available to transmit traffic to or from the specified nodes. 
         [0064]    Next, the availability determination tool accesses, or allows the user to access a reporting module  1240 , which reports the available paths of the paths connecting at least two nodes, and reports the available paths having at least one available wavelength and the wavelength availability along the available paths  1241 . In some embodiments of the present invention, the reporting module  1240  can display to the user a tabular, graphical, pictorial format, or a combination of these formats, in order for the user to visualize or receive reports of wavelength availability. 
         [0065]      FIG. 13  is a flow chart that illustrates a fourth example embodiment of a method  1300  that displays and identifying available wavelengths across a topology  1375 , according to the disclosed availability determination tool. As in the embodiment illustrated in  FIG. 11 , the display module  1312  of this example embodiment performs in substantially the same method as display module  1112 . 
         [0066]    Next, an enabling module  1320 , enables a user  1380  to input information (viewed from the display module  1312 ) by selecting at least two nodes  1310  of the topology  1375 . The enabling module  1320  can further include physical links  1315  to form paths  1325  that can be a protected path  1360  or an unprotected path  1365  through the topology  1375 . 
         [0067]    Next, a determination module  1330  determines paths  1325  that connect the nodes  1310 , and further determines the wavelength availability  1305  along the paths  1325 . The determination module  1330  can further determine the subrate availability  1345  and transmit that availability information to the reporting module  1340 . The determination module  1330  further includes a wavelength interchange module  1355 , which determines alternative paths using wavelength conversion to reroute wavelengths, thereby changing the wavelength availability. 
         [0068]    Next, a reporting module  1340  enables the user  1380  to view the information that an embodiment of the present invention processes, by reporting the available paths  1325  of the paths that include connecting the specified nodes  1310 , and of the available paths  1325 , having at least one available wavelength. The reporting module  1340  further reports the available paths  1325  and the display module  1312  displays the available paths  1325 , along with the topology  1375  and the wavelength availability  1305 . Some embodiments of the present invention can include a reporting module  1340  that can further configure the display module  1312  to display the entire topology  1375  and the available paths  1325  in a base plane of a three-dimensional view  1370 . The display module  1312  further displays the wavelength availability  1305  in the three-dimensional view  1370 , with each available wavelength represented in a respective plane elevated above the base plane. 
         [0069]    The reporting module  1340  can further report any, all, or some appropriate combination of elements, which are determined by an embodiment of the present invention, in a tabular format  1372  that could include highlighting the wavelength availability  1377 . In some embodiments of the present invention, the reporting module  1340  can display to the user  1380  a tabular  1372 , graphical, pictorial format, or a combination of these formats, in order for the user  1380  to visualize or receive reports of wavelength availability, or any other suitable elements. 
         [0070]      FIG. 14  is a block diagram that illustrates an example embodiment of a wavelength availability determination apparatus  1400 , according to the disclosed availability determination tool. The apparatus models the topology, such as the one shown in  FIG. 3 , to provide the availability of wavelengths in the topology. The apparatus  1400  includes a display module  1412 , an enabling module  1420 , a determination module  1430 , and a reporting module  1440 . The display module  1412  displays a representation of nodes and physical links of the topology; the enabling module  1420  enables selection of the representation of physical links to form a path through a network; the determination module  1430  determines wavelength availability along the path; and the reporting module  1440  reports the wavelength availability determined along the path. 
         [0071]      FIG. 15  is a block diagram that illustrates a second example embodiment of a wavelength availability determination apparatus  1500 , according to the disclosed availability determination tool. Like the example shown in  FIG. 14 , the apparatus  1500  includes a display, an enabling, a determination, and a reporting module  1512 ,  1520 ,  1530 ,  1540 , which can be controlled by a central processing unit (CPU)  1508  operating in conjunction with random access memory (RAM)  1509 . In the apparatus  1500 , the display module  1512  displays to a user  1580  representations of nodes  1510  and physical links  1515  of a topology  1575 . In an example embodiment of the present invention, the nodes  1510  could include at least one ROADM  1550 . 
         [0072]    Next, the enabling module  1520 , enables the user  1580  to input information (viewed from display module  1512 ) by selecting from the representation of the physical links  1515  to form a path  1525  through the topology  1575 . The enabling module  1520  can further include physical links  1515  to form paths  1525 , which can be a protected path  1560  or an unprotected path  1565  through the topology  1575 . 
         [0073]    Next, a determination module  1530 , determines wavelength availability  1505  along the path  1525  and a subrate availability  1545 , and provides this information to a reporting module  1540 , as described below in more detail. The determination module  1530  can further include a wavelength interchange module  1555 , which allows the system to redirect, deflect, switch, or reroute a wavelength in order to change the wavelength availability in a network or sub-network. 
         [0074]    Next, the reporting module  1540  enables the user  1580  to view the information that an embodiment of the present invention processes, by configuring the display module  1512  to display the wavelength availability  1505  of at least a subset of the wavelengths along the path  1525 . In an embodiment of the present invention, the reporting module  1540  receives the determinations regarding wavelength availability  1505  along the path  1525  and the subrate availability  1545  from the determination module  1530  (as described above) and reports the information in the report of the wavelength availability. The reporting module  1540  can further display the wavelength availability  1505  and configure the display module  1512  to display the representation of a node  1510  and a physical link  1515  of the topology  1575 . 
         [0075]    In an example embodiment of the apparatus  1500 , the reporting module  1540  can further configure the display module  1512  to display the representation of a node  1510  and a physical link  1515  in a base plane of a 3-D view  1570 . Further, the display module  1512  displays the available wavelengths as part of the 3-D view  1570  in respective planes elevated above the base plane. In some embodiments of the present invention, the reporting module  1540  can further configure the display module  1512  to display elements of the determination module  1530  in a tabular format, which could include highlighting the wavelength availability. In some embodiments, the elements of the determination can include any of the subrate availability  1545 , the paths  1525 , the wavelength availability  1505 , the nodes and physical links  1515  of the topology  1575 , or any other suitable elements that can be determined by the availability determination tool. In some embodiments of the present invention, the reporting module  1540  can display to the user  1580  a tabular, graphical, pictorial format, or a combination of these formats, in order for the user  1580  to visualize or receive reports of the wavelength availability, or any other suitable elements. 
         [0076]      FIG. 16  is a block diagram, similar to  FIG. 14 , which illustrates a third example embodiment of a wavelength availability determination apparatus  1600 , according to the disclosed determination tool. This example embodiment of an apparatus models a topology, such as the one shown in  FIG. 3 , and provides the availability of wavelengths in the topology. The apparatus  1600  includes a display module  1612 , an enabling module  1620 , a determination module  1630 , and a reporting module  1640 . The display module  1612  displays a representation of nodes and physical links of the topology; the enabling module  1620  enables selection of at least two nodes of the topology; the determination module  1630  determines paths connecting at least two nodes through the topology, as well as, the wavelength availability along the paths; and the reporting module  1640  reports available paths of the paths connecting at least two nodes and the wavelength availability along the available paths. 
         [0077]      FIG. 17  is a block diagram, similar to  FIG. 15 , which illustrates a fourth example embodiment of a wavelength determination apparatus  1700 , according to the disclosed determination tool. This example embodiment of an apparatus models a topology  1775 , such as the one shown in  FIG. 3 , and provides the availability of wavelengths, and other suitable elements as described above, in the topology  1775 . Like the example shown in  FIG. 16 , the apparatus  1700  includes the a display, an enabling, a determination, and a reporting module  1712 ,  1720 ,  1730 ,  1740 , which can be controlled by a central processing unit (CPU)  1708  operating in conjunction with random access memory (RAM)  1709 . 
         [0078]    In an embodiment of the present invention, in the apparatus  1700 , the display module  1712  displays to a user  1780  representations of nodes  1710  and physical links  1715  of the topology  1775 , where the nodes  1710  could include at least one ROADM  1750 . Next, the enabling module  1720 , enables the user  1780  to input information (viewed from the display module  1712 ) by selecting at least two nodes  1710  of the topology  1775 . The enabling module  1720  can further include physical links  1715  to form paths  1725 , which can be a protected path  1760  or an unprotected path  1765  through the topology  1775 . 
         [0079]    Next, the determination module  1730  determines paths  1725  that include connecting at least two nodes  1710  and determines the wavelength availability  1705  along the paths  1725 . The determination module  1730  can further determine the subrate availability  1745 . The determination module  1730  can further send the subrate availability  1745  information to the reporting module  1740 . The determination module  1730  can further include a wavelength interchange module  1755 , which determines alternative paths  1725  using wavelength interchange to reroute wavelengths, thereby changing the wavelength availability. 
         [0080]    Next, the reporting module  1740  enables the user  1780  to view the information that an embodiment of the present invention processes, by reporting the available paths  1725  of the paths that include connecting at least two nodes  1710  and of the available paths  1725 , having at least one available wavelength. The reporting module  1740  can further report the available paths  1725  and configure the display module  1712  to display the available paths,  1725  along with the topology  1775 , and display the wavelength availability  1705 . 
         [0081]    An embodiment of the present invention can include a reporting module  1740  that can further configure the display module  1712  to display the entire topology  1775  and the available paths  1725  in a base plane of a three-dimensional view  1770 . The display module  1712  further displays the wavelength availability  1705  in the three-dimensional view  1770 , with each available wavelength represented in a respective plane elevated above the base plane. The reporting module  1740  further reports any, all, or some appropriate combination of elements that are determined by an embodiment of the present invention, in a tabular format that can include highlighting the wavelength availability. In some embodiments of the present invention, the reporting module  1740  can display to the user  1780  a tabular, graphical, pictorial format, or a combination of these formats, in order for user  1780  to visualize or receive reports of wavelength availability or any other suitable elements. 
         [0082]    It should be understood that the examples presented herein can include more or fewer components, be partitioned into subunits, or be implemented in different combinations. Moreover, the flow and block diagrams of  FIGS. 10-17  may be implemented in at least hardware, firmware, or software. If implemented in software, the software may be written in any suitable software language. The software may be embodied on any form of computer readable medium, such Random Access Memory (RAM), Read-Only Memory (ROM), magnetic or optical disk, or any other tangible embodiment, and loaded and executed by generic or custom processor(s). 
         [0083]    While this invention has been particularly shown and described with references to example embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims. Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described specifically herein. Such equivalents are intended to be encompassed in the scope of the claims.