Abstract:
A method for the simultaneous graphical display of paths of optical wavelength channels in a telecommunications network together with one or more channel attributes is provided. The graphical display of the network also shows the direction of data flow transported by the channels. An audible or visual alarm for an error condition for a channel attribute on a link in the network can be produced if requires. The operator can also obtain detailed information on a channel by positioning the mouse over a channel.

Description:
FIELD OF THE INVENTION  
         [0001]    The invention relates to optical networks, and in particular to visualization of the topology of an optical network.  
         BACKGROUND OF THE INVENTION  
         [0002]    As communications networks have grown in complexity, the task of effective network management has become increasingly important.  
           [0003]    An important aspect of network management is the topology of the network, which traditionally includes network connectivity. Equally important for effective network management and planning is information concerning configuration and performance characteristics, such as bandwidth and load.  
           [0004]    The visual representation of networks in traditional network management systems is limited to the topology and connectivity of the network, see, e.g. a publication by John Jamison et al “vBNS: not your father&#39;s Internet” at http://www.vbns.net/index.html?g=2&amp;t=97&amp;i=264&amp;URL=papers/notyour /notyourf.html; “Map of an Aggregated View of the MBGP Topology” ,http://www.caida.org/tools/measurement/Mantra/topology /topo-java/global-view.html; Ndn-map from NORDUnet, (Nordic Internet Highway to Research and Education Networks in Nordic Countries) http://www.nordu.net/stat-q/load-map/ndn-map,,traffic,busy; and promotional brochure “High Performance Nationwide IP Network” of WorldCom at http://www.vbns.net. Unfortunately, none of the current technologies provides adequate visualization for monitoring both network topology and network performance.  
           [0005]    Accordingly, there is a need for the development of an improved method for visualization of an optical network topology, which would be particularly applicable to wavelength channel visualization.  
         SUMMARY OF THE INVENTION  
         [0006]    It is therefore an object of the invention to provide a method for visualization of the topology of an optical network, which would avoid the afore-mentioned drawbacks.  
           [0007]    According to one aspect of the invention there is provided a computer-implemented method for visualization of the topology of optical network, comprising the steps of:  
           [0008]    determining a channel identifier for a channel travelling in the network;  
           [0009]    determining a path of the channel in the network by using the channel identifier;  
           [0010]    graphically displaying the path of the channel in the network including displaying a direction of propagation of the channel in the network.  
           [0011]    Advantageously, the method further comprises the step of determining an attribute of the channel along the path of the channel in the network, the step being performed before the step of displaying, wherein the step of graphically displaying the path of the channel in the network comprises graphically displaying the path of the channel in the network together with the evolution of the channel attribute along the path.  
           [0012]    Beneficially, the step of determining the channel identifier comprises determining the wavelength of the channel, and the step of determining the attribute of the channel comprises determining one or more of the following attributes of the channel: power, bit error rate, dispersion factor or optical return factor.  
           [0013]    Conveniently, the step of graphically displaying the path of the channel comprises graphically displaying the path of more than one channel simultaneously, and for each channel, displaying more than one channel attribute simultaneously.  
           [0014]    The step of graphically displaying the path of the channel, comprising displaying of the channel attributes, may be performed by using graphical display characteristics such as color, shading, pattern and/or geometrical shape.  
           [0015]    Conveniently, the step of displaying the path of the channel may comprise representing the path by a geometric shape, the geometrical shape being substantially a line, the thickness of the line representing the value of the channel attribute to be displayed. The step of displaying the path of the channel in the network may further comprise displaying one more channel attribute by using a filling of the thickness of the line, the filling being one of the pattern and shading, variations of the filling representing the evolution of the value of the channel attribute. If additional channel attributes have to be displayed, it may be done in the following manner: the geometrical shape representing the path of the channel in the network may be split into segments, each segment corresponding to the path of the channel between two nodes, and each segment may further be split into sections whose number is equal to the number of the attributes to be displayed, wherein each section uses a distinct graphical display characteristic and represents the value of the corresponding attribute between the two nodes.  
           [0016]    Conveniently, the step of graphically displaying the path of the channel in the network comprises displaying the path of the channel on a computer screen. The step of determining the attribute of the channel along the path of the channel in the network may comprise customized selection of the attribute from a menu. Similarly, the step of simultaneously displaying the path of more than one channel in the network may comprise the step of customized selection of the channels from a menu.  
           [0017]    Advantageously, the step of graphically displaying the path of the channel in the network comprises refreshing the graphical displaying of the channel path in response to a signal, the refreshed graphical display incorporating changes which occurred in the network since previous graphical displaying. The step of refreshing the graphical display comprises refreshing the graphical display in response to an external signal. Conveniently, the step of refreshing may comprise refreshing of the graphical display at discrete time intervals.  
           [0018]    If required, the step of graphically displaying the path of the channel in the network may further comprise displaying the value of the channel attributes in a text information box. The step of displaying the value of channel attributes in the text information box may comprise displaying the text information box in response to the movement of a screen pointing device over the path of the channel in the network, the text information box showing the value of the channel attributes at the position along the path of the channel in the network, indicated by the pointing device.  
           [0019]    Beneficially, the step of displaying the path of the channel in the network further comprises the step of generating one of the audible and visual alarm if an error condition along the path of the channel occurs.  
           [0020]    According to another aspect of the invention there is provided a computer program product for visualizing topology of an optical network, comprising:  
           [0021]    computer usable medium having computer readable program code means embodied in said medium for causing a computer to visualize the topology of the network, said computer program product having:  
           [0022]    computer readable program code means for causing said computer to determine a channel identifier for a channel travelling in the network;  
           [0023]    computer readable program code means for causing said computer to determine a path of the channel in the network by using the channel identifier; and  
           [0024]    computer readable program code means for causing said computer to graphically display the path of the channel in the network including displaying a direction of propagation of the channel in the network.  
           [0025]    According to yet another aspect of the invention there is provided a computer program for visualization of topology of an optical network, comprising:  
           [0026]    computer readable program code means for causing a computer to determine a channel identifier for a channel travelling in the network;  
           [0027]    computer readable program code means for causing said computer to determine a path of the channel in the network by using the channel identifier; and  
           [0028]    computer readable program code means for causing said computer to graphically display the path of the channel in the network including displaying a direction of propagation of the channel in the network.  
           [0029]    The described method of visualization of the network topology has the following advantages. It provides more effective monitoring of the network performance and ensures much easier and more reliable control of operation of the network. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0030]    The invention will be further understood from the following description, with reference to the accompanying drawings in which:  
         [0031]    [0031]FIG. 1 a  is a diagram illustrating the graphical display of an optical network topology according to a first embodiment of the invention;  
         [0032]    [0032]FIG. 1 b  is a diagram illustrating a user interface dialog box used to select channels and channel attributes for the graphical display of FIG. 1 a;    
         [0033]    [0033]FIG. 1 c  is a diagram illustrating a user interface dialog box used to select display preferences for the graphical display of FIG  1 `a;  
         [0034]    [0034]FIG. 2 a  is a diagram illustrating the graphical display of an optical network topology according to a second embodiment of the invention;  
         [0035]    [0035]FIG. 2 b  is a diagram illustrating a user interface dialog box used to select channels and channel attributes for the graphical display of FIG. 2 a;    
         [0036]    [0036]FIG. 3 a  is a diagram illustrating the graphical display of an optical network topology according to a third embodiment of the invention;  
         [0037]    [0037]FIG. 3 b  is a diagram illustrating a user interface dialog box used to select channels and channel attributes for the graphical display of FIG. 2 a;    
         [0038]    [0038]FIG. 4 a  is a diagram illustrating the graphical display of an optical network topology according to a fourth embodiment of the invention;  
         [0039]    [0039]FIG. 4 b  is a diagram illustrating a user interface dialog box used to select channels and channel attributes for the graphical display of FIG. 4 a;    
         [0040]    [0040]FIG. 5 is a table illustrating graphical representation of channel attributes used in the graphical display of FIG. 4 a;    
         [0041]    [0041]FIG. 6 a  is a diagram illustrating the graphical display of an optical network topology according to a fifth embodiment of the invention;  
         [0042]    [0042]FIG. 6 b  is a diagram illustrating a user interface dialog box used to select channels and channel attributes for the graphical display of FIG. 6 a;    
         [0043]    [0043]FIGS. 6 c  and  6   d  illustrate the graphical display of the network topology of FIG. 6 a  when several channel attributes are displayed simultaneously.  
         [0044]    [0044]FIG. 7 a  is a diagram illustrating the graphical display of an optical network topology according to a sixth embodiment of the invention; and  
         [0045]    [0045]FIG. 7 b  is a diagram illustrating a user interface dialog box used to select channels and channel attributes for the graphical display of FIG. 7 a.   
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0046]    [0046]FIG. 1 a  illustrates the visualization of an optical network by means of a graphical display  10 , according to a first embodiment of the invention. The network comprises four network elements called nodeA, nodeB, nodeC and nodeD, and labeled  12 ,  14 ,  16  and  18  respectively. An optical fiber link  20  connects NodeA to nodeB, another link  22  connects nodeB to nodeC, yet another link  24  connects nodeC to nodeD, and link  26  connects nodeD to nodeA. An optical wavelength channel  28 , hereinafter referred to as a channel, is shown being carried by the optical fiber  20  between the nodeA  12  and nodeB  14 . The same channel  28  is carried by optical fiber  22  between nodeB  14  and nodeC  16 , and again by optical fiber  24  between nodeC  16  and nodeD  18 . Thus, the channel  28  traverses a path between nodeA  12  and nodeD  18 , comprising three segments (fiber links  20 ,  22  and  24  respectively), each segment being highlighted with an identifying pattern, a long dash and two dots in FIG. 1 a . FIG. 1 b  illustrates an exemplary user interface dialog box  34  used by the operator to select the highlighting of the path of channel  28  in the graphical display  10 . In the dialog box  34 , the operator has chosen highlighting for channel  28  in the graphical display  10  by selecting checkbox  38 , with the channel identifier λ 1  labelled  40  and the line pattern  42 . A pop-up dialog box  50  for the attributes of the λ 1  channel is shown in FIG. 1 b , with four unselected checkboxes  52 ,  54 ,  56 ,  58  for the Power, Bit Error Rate (BER), Dispersion Factor, and the Optical Return Factor (ORF), respectively, indicating that attributes for the channel λ 1  are not to be indicated in the graphical display  10 . Another checkbox  44  is shown for a second channel λ 2 , but is not selected, indicating the operator has chosen neither the channel nor attributes for the second channel λ 2  to be highlighted in the graphical display  10 .  
         [0047]    [0047]FIG. 1 c  illustrates an exemplary user interface dialog box  59  used by the operator to select display preferences for the graphical display  10 . The operator selects the radio button  59   a  to refresh the graphical display continuously, so changes to the network are updated on the graphical display  10  in real-time. Alternatively, the operator may select the radio button  59   b  to refresh the graphical display  10  only when the operator requests, or yet alternatively the operator may select the radio button  59   c  to refresh the graphical display  10  at discrete intervals. In this case, the dialog box  59   d  is activated, allowing the user to change the number of seconds  59   e  between refreshing the graphical display  10 . If the radio button  59   a  or  59   b  is selected, the dialog box  59   d  is greyed out and is inactive.  
         [0048]    Thus, the automatic visualization of the topology of the optical network is provided, including a path of the wavelength channel in the network.  
         [0049]    [0049]FIGS. 2 a  and  2   b  illustrate the visualization of an optical network topology by a graphical display according to the second embodiment of the invention. The graphical display  100  is similar to that of the first embodiment, except the direction of the data carried by the optical channel  128  is indicated by an arrow  128   a . Similar elements in FIGS. 1 a  and  1   b  and FIGS. 2 a  and  2   b  are designated by the same reference numerals incremented by  100  respectively. FIG. 2 b  illustrates an exemplary user interface dialog box  134  used by the operator to select the highlighting of channels in the graphical display  100 . In the dialog box  134 , the operator has chosen highlighting for channels  128  with the channel identifiers λ 1  in the graphical display  100  by selecting checkbox  138 . The line pattern  142  is shown to identify the channel λ 1  in the graphical display  100 . Consequently, the direction of data carried by a channel is shown, providing a means for more effective management of optical wavelength channels in a network.  
         [0050]    [0050]FIGS. 3 a  and  3   b  illustrate graphical display of the third embodiment of the invention. The graphical display  200  is similar to that of the second embodiment, except a plurality of channels are selected for highlighting by the operator. Similar elements in FIGS. 2 a  and  2   b  and FIGS. 3 a  and  3   b  are designated by the same reference numerals, incremented by  100  respectively. In the exemplary user interface dialog box  234 , illustrated by FIG. 3 b , the operator has chosen to select the highlighting of channels λ 1 , λ 2  and λ 3  in the graphical display  200 .  
         [0051]    Thus, the automatic visualization of the topology of the optical network is provided, including simultaneous graphical display of paths and directions of propagation of several optical wavelength channels, thereby providing a means for more efficient monitoring of the network topology.  
         [0052]    [0052]FIGS. 4 a  and  4   b  further illustrate a graphical display of an optical network topology according to the fourth embodiment of the invention. The graphical display  300  is similar to that of the third embodiment, except the channel attributes for the channel λ 1  are selected for the display by the operator. Similar elements in FIGS. 3 a  and  3   b  and FIGS. 4 a  and  4   b  are designated by the same reference numerals, incremented by  100 . In the pop-up dialog box  350  for channel λ 1 , the operator has chosen to highlight only the power attribute  378  for the λ 1  channel by selecting only the power attribute checkbox  378 . This attribute indicates the average power level for the channel on the indicated optical fibre optic link between two network elements. The highlighting of the power in the graphical display  300  for channel λ 1  is shown by different widths of a set of rectangles  376   a ,  376   b  and  376   c  where the λ 1  channel is carried. The channel identification for channel λ 1  is indicated by the line pattern  342  on the edge of the rectangles  376   a ,  376   b  and  376   c , as indicated by the line pattern  342  for channel λ 1  in dialog box  334  in FIG. 4 b.    
         [0053]    Thus, the automatic visualization of the optical network topology is provided, including paths, directions of propagation and attributes for the optical channels in the network.  
         [0054]    [0054]FIG. 5 shows a table, which illustrates four exemplary attributes for a channel, namely, Power, Bit Error Rate, Dispersion Factor and Optical Return Factor. Each attribute has four 25% quartile percentage ranges, each range of each attribute using a unique graphical user interface characteristic to identify the range on the graphical display of the network. Each percentage range for each attribute has an associated meaning, i.e. the quantitative range of variation of the attribute. The power attribute indicates the average power level for a channel between two network elements, and each percentage quartile range is identified by different widths of a box for the optical fiber link between two network elements, where the lowest average power is indicated by the narrowest box, and the highest average power by the widest box. The percentage quartile range values for the Bit Error Rate (BER), Dispersion Factor and Optical Return Factor (ORF) attributes are indicated by unique monochromatic shading for each attribute, where the lowest value for an attribute is indicated by the most sparse shading, and the highest value for an attribute is indicated by the most dense shading. The meaning of each quartile range for each attribute is given, where applicable.  
         [0055]    [0055]FIGS. 6 a  and  6   b  illustrate graphical display  400  of the network topology according to the fifth embodiment of the invention. The graphical display  400  is similar to that of the fourth embodiment, except two channel attributes for the channel λ 1  are selected for the display by the operator, and one channel attribute for one of the λ 2  and λ 3  channels is selected. Similar elements in FIGS. 4 a  and  4   b  and FIGS. 6 a  and  6   b  are designated by the same reference numerals, incremented by  100 . In the dialog box  450   a , the operator has chosen to highlight the power attribute and the BER attribute for channel λ 1  by selecting the checkboxes  478 ,  480  respectively. The operator has also chosen to highlight the power attribute for channel λ 3  by selecting the checkbox  490  in dialog box  450   b . In FIG. 6 a , the power attribute for channel λ 3  is indicated by the width of the rectangles  484   a  and  484   b . For illustration purposes only, an additional nodeE designated by reference numeral  483  is also shown in the network.  
         [0056]    Thus, the topology of an optical network is provided, simultaneously showing paths, directions of propagation and attributes of several channels in the network, thereby providing a more immediate and effective visualization of the topology and performance of the network.  
         [0057]    If the paths of the channels selected for the graphical display overlap either partly or entirely, the paths and associated attributes for different channels may be displayed beside each other so that not to block each other.  
         [0058]    In a modification to the  5 th embodiment, if more than one channel attribute has to be simultaneously displayed, the segment of channel path between the two network elements can be split into a number of sections  401 ,  402 ,  403  either vertically as shown in FIG. 6 c  or horizontally as shown in FIG. 6 d , the number of sections being equal to the number of the attributes to be displayed. Then each attribute is graphically represented in the corresponding section of the path segment for the selected channel.  
         [0059]    Generalizing the approach explained with regard to FIGS. 6 c  and  6   d , the following approach may be used to display an additional number of channel attributes. The geometrical shape, representing the path of the channel in the network, may be split into segments so that each segment corresponds to the path of the channel between two nodes. Each segment may further be split into sections whose number is equal to the number of the attributes to be displayed wherein each section uses a distinct graphical display characteristic and represents the value of the corresponding attribute between the two nodes.  
         [0060]    [0060]FIGS. 7 a  and  7   b  illustrate a graphical display  500  of the optical network topology according to the sixth embodiment of the invention. The graphical display  500  is similar to that of the fourth embodiment, except a text information box  596  is displayed. Similar elements in FIGS. 4 a  and  4   b  and FIGS. 7 a  and  7   b  are designated by the same reference numerals, incremented by  200  respectively. In the example shown in FIG. 7 b , the operator has chosen to highlight channel λ 1  by selecting the checkbox  538  in dialog box  534 . The operator has also chosen to highlight the power attribute for channel λ 1  by selecting the checkbox  578  in dialog box  550 . In the graphical display  500 , the operator has moved the graphics input device cursor  594  over the channel attribute display  576   a  for channel λ 1 . As a result, a text information box  596  is displayed, containing the channel identifier, the fiber identifier and the value for the selected power attribute. This provides a means for both visualizing the topology and attributes of the network, and for monitoring the performance of an individual channel in more detail.  
         [0061]    In a modification to the above embodiments, an audible alarm and/or visual alarm, e.g. flashing, can be produced when an error condition occurs for a channel attribute on a link between the two nodes in the network, the error condition indicating, e.g. low power, high bit error rate, low dispersion factor or low optical return factor. Thus, a means is provided for alerting the operator when an error occurs anywhere in the network, permitting more effective monitoring of the health of the network.  
         [0062]    Various graphical display characteristics may be used for the graphical display in the embodiment of the invention, including shading, pattern, variations in geometrical shape and other techniques. While in the embodiments described above, a monochromatic graphical characteristics have been used for visualization of different channels and their attributes, it is contemplated that other graphical display characteristic tics may be also used, including color coded techniques, for unique identification of channels and associates attributes in the network.  
         [0063]    The embodiment of the invention has the following advantages. By providing graphical visualization of the path of the channel in the network accompanied by simultaneous graphical visualization of channel attributes, it guarantees more effective monitoring of the network performance and provides easier and more reliable control of operation of the network.  
         [0064]    Although specific embodiments of the invention have been described in detail, it will be apparent to one skilled in the art that variations and modifications to the embodiments may be made within the scope of the following claims.