Abstract:
An apparatus and method are disclosed for verifying that a description of a network corresponds to communication paths of the network. The verification is accomplished by accessing data that represents of a plurality of logical links of the network. A determination is made whether each of the logical links correspond to a communication path of the network. This determination utilizes criteria, which includes: link data; adapter data; and connection data. Thereafter, an indication of whether the logical links correspond to communication paths of the network is provided. If each logical link does not have a corresponding communication path, additional information related to the reason for the non-correspondence may be provided.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates generally to verifying a description of a network and, more particularly, to confirming that the description of the network is consistent with communication paths of the network.  
       BACKGROUND OF THE INVENTION  
       [0002]     Networks, such as communication networks, transmit various types of data concurrently, such as text, voice, video and other multimedia files. Communication networks are becoming increasingly complex, especially due to their increasing speeds of operation, the number of interconnected devices and the formation of large networks from sub-networks. Another factor increasing the complexity of communication networks is the layered nature in which a logical link at one technological level is provided as a service by a different technology level. For example, a web browser process might establish a TCP (Transmission Control Protocol) connection to a server process; the connection appears to the two processes as a link. In fact, data sent across the connection traverses an underlying connectionless IP (Internet Protocol) network; a link in the IP network might be provided by a complex hierarchy of connection-oriented ATM (Asynchronous Transfer Mode), SONET (Synchronous Optical Network), and DWDM (Dense Wavelength Division Multiplexing) networks. The layering complexity of networks can only be expected to increase in the future, with the advent of wireless links, virtual private networks and overlaid protocols, such as SIP (Session Initiation Protocol).  
         [0003]     Computer tools may be used to design, inventory, analyze, optimize and test networks. These computer tools need a language to describe networks, and fundamental to any such language is a model of network topology, which is a set of links and connections in the network. Conventional computer tools do not permit a uniform network description across multiple levels. Each specific network technology typically has an associated description provided by a standards document; these technology descriptions are usually very detailed and not easily abstracted. Conventional computer tools may use a specific model of network topology; however, the definition of a term in the model of one tool may not match the definition of the same term of another tool. This inconsistency requires a detailed analysis of the semantic model to transfer data between tools.  
         [0004]     Thus, conventional approaches do not provide models that can uniformly describe networks across multiple levels. Therefore, it would be an advancement in the art to be able to efficiently confirm that a network is operating according to its specifications.  
       SUMMARY OF THE INVENTION  
       [0005]     Generally, a method and system are disclosed for verifying a description of a network represented by network map data. Logical links of a network are accessed and a determination is made whether each logical link corresponds to a network communication path. The network communication path is represented by physical link data, connection data, and adapter data.  
         [0006]     If the logical links correspond to the communication paths, an affirmative indication is generated. If the logical links do not correspond to the communication paths, a negative indication is generated. These indications can be provided to an output module.  
         [0007]     A more complete understanding of the present invention, as well as further features and advantages of the present invention, will be obtained by reference to the following detailed description and drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  illustrates a network environment in which the present invention can operate;  
         [0009]      FIG. 2  is a schematic block diagram of the terminal of  FIG. 1 ;  
         [0010]      FIG. 3  shows an example of a schematic representation of logical map data and physical map data;  
         [0011]      FIG. 4  shows an example of a representation of physical link data;  
         [0012]      FIG. 5  shows an example of a representation of adapter data;  
         [0013]      FIG. 6  shows an example of a representation of connection data;  
         [0014]      FIG. 7  shows an example of a representation of binding data; and  
         [0015]      FIGS. 8A-8C  show a flowchart of steps for a verification algorithm according to the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0016]     The present invention provides an algorithm to verify a description of the topology of a network. This verification is a pre-condition for many algorithms that manipulate such descriptions, including algorithms that perform network optimization and reorganization, summarize traffic, compute reliability, detect recent changes and analyze alarms. As discussed further below, the topology of the network is described in a language, such as, for example, NetML, which is a language for recording the physical and logical topology of a communications network. NetML is an XML-based language that is applicable across multiple network levels and to a variety of network technologies. Fundamental to NetML is a formal topology model that includes network map data, which is, for example, an abstract computer representation of a network. The network map data includes: physical map data, which represents a set of communication paths; logical map data, which represents a plurality of logical links; and binding data, which represents an association, relationship or correlation between the physical map data and the logical map data.  
         [0017]     A verification algorithm, which may use NetML syntax, validates the network map data by establishing that each logical link of the logical map data corresponds to a communication path of the physical map data. The physical map data is analyzed to determine communication paths using physical link data, which is representative of an association of two physical end ports, adapter data, which is representative of adapter type and layer, and connection data, which is representative of an association of two physical ports of a physical link or a physical port of a physical link and a port of an adapter. An indication of whether each of the logical links corresponds to a communication path is provided to an output facility, such as a user interface or display device. If each logical link of the logical map data corresponds to a conductive path, the network map data is consistent, or valid; if not, the network map data is determined to be inconsistent, or invalid, and thus does not accurately represent the network it models.  
         [0018]      FIG. 1  illustrates a network environment  100  in which the present invention can operate. A user employing a terminal, or workstation  102 , accesses remote processing terminals, or facilities,  112 ( a ) through ( n ) (where n is any suitable number), customer premise equipment (CPE)  150 ( a ) through ( n ) (where n is any suitable number) and server terminal  106 , via a network  108 . Network  108  is a network of interconnected terminals or devices. Network  108  may be, for example, a LAN (local area network), a WAN (wide area network), Internet, a PSTN (public switched telephone network), a WLAN (wireless local area network), a PBX (private branch exchange) or combinations thereof, or other interconnection of processing or communication devices.  
         [0019]     Server  106  and facilities  112 ( a ) through ( n ) (generally referred to herein as facilities  112 ) are typically servers, or other computing devices, with memory and processing capability, coupled to network  108  via associated bi-directional transmission media  136  and  132 ( a ) through ( n ), respectively. The CPE  150 ( a ) through ( n ) (generally referred to herein as CPE  150 ) may be, for example, telephone devices, PBX (private branch exchange) equipment, facsimile machines, scanners, or any other equipment arranged to be connected to network  108 , via associated interconnection media  152 ( a ) through ( n ) (where n is any suitable number) (generally referred to herein as interconnection medium  152 ). The interconnection medium  152  are, for example, wired or wireless connections. The user may access remote server terminal  106 , facilities  112  and CPE  150  using software, such as an applet, operating among the terminal  102 , the network  108 , and the server terminal  106 , facilities  112  and CPE  150 .  
         [0020]     Terminal  102 , which is coupled to network  108  via interconnection medium  142 , may be, for example, a personal computer (PC), hand-held device (e.g. PDA), or other processing module, as discussed further below in conjunction with  FIG. 2 . The terminal  102  has adequate memory and adequate processing speed to retrieve network data from remote locations and process, store and output data.  
         [0021]     An abstraction, or description of the network topography, also referred to herein as network map data, or a network map, describes network connections, and may be stored at a remote location, such as server terminal  106  and accessed by terminal  102 . One way to process the network map data is to download it to terminal  102 , process the data and store an indication either at terminal  102  or at a remote location.  
         [0022]     The terminal  102  can access a verification algorithm that processes the network map data to determine whether it is valid. For example,  FIG. 1  shows connections between network  108  and facilities  112  and CPE  150 , which may be a source of the network map data, as well as the network used to provide the environment in which the present invention operates.  
         [0023]      FIG. 2  is a schematic block diagram of the terminal  102  shown in  FIG. 1 . Terminal  102  includes: a central processing unit (CPU)  226 ; a memory module  216 ; a display device (shown as element  118  in  FIG. 1 ); input device (shown as element  116  in  FIG. 1 ); and other peripheral devices (not shown). Terminal  102  may be embodied as a commercially available computing system such as a PC or workstation, and may include other conventional components and peripherals that are not shown in  FIG. 2 .  
         [0024]     The processor  226  may be used to access and process the data stored in memory  216 .  
         [0025]     The memory  216  typically includes read only memory (ROM) (not shown), random access memory (RAM) (not shown) and an operating system (not shown). Memory  216  stores the network map data  218  and verification algorithm  800 . Network map data  218  includes logical map data  301 , physical map data  302  and binding data  700 . Physical map data  302  includes physical link data  400 , adapter data  500  and connection data  600 . The components of memory  216  are discussed below in conjunction with  FIGS. 3-8 .  
         [0026]     While  FIG. 2  shows that the verification algorithm  800  is stored as program code in a single location, the verification algorithm  800  may also include sections of code stored in more than one location and accessed as necessary. The memory  216  may also store an output from the verification algorithm  800 .  
         [0027]     Although only one central processing unit (CPU)  226  is shown in  FIG. 2 , there may be a plurality of such units, depending on the application.  
         [0028]     In order to verify the network map data, it is necessary to describe the network topology. NetML is one language that can be used to describe the topology of a telecommunications network, which includes physical links, logical links, ports and internal cross-connects. NetML is an interchange language that can conform to a particular XML schema. To promote interoperability of tools, NetML is based on a model that is independent of any particular technology and applicable to most common technologies. NetML assigns physical links a type, or layer, which characterizes the format of the data. NetML identifies a link independent of network hierarchy and uniformly incorporates both circuit-switched networks, such as SONET, and packet-switched networks, such as IP and Ethernet, allowing descriptions of communications paths that traverse both packet and circuit switched networks. NetML also provides an XML representation that allows interchange of network descriptions among computer tools.  
         [0029]      FIG. 3  shows an example of a schematic representation  300  of logical map data  301  and physical map data  302 , which may be generated using NetML, stored in memory and analyzed, processed and manipulated by a processor.  
         [0030]     Logical map data  301  shows logical link  332 , which is a representation of a communication path from logical link port  330  to logical link port  331 . Typically, logical map data  301  includes a plurality of logical links; however,  FIG. 3  shows a single logical link  332  for explanation purposes. In order to confirm that the logical link  332  actually corresponds to a communication path between ports  330  and  331 , the physical map data  302  and binding data (shown as element  700  in  FIG. 2 ) are analyzed using the verification algorithm (shown as element  800  in  FIG. 2 ).  
         [0031]     Physical map data  302  includes physical link data, adapter elements and network elements. These components are discussed in more detail below.  
         [0032]     Physical Link Data  
         [0033]     Generally, physical link data includes one or more physical links. A physical link represents an ability to transmit data from one place to another and has two ports, one being a start port and the other being an end port.  
         [0034]     A physical link is characterized by its layer. A layer is an aggregate set of conventions required to interpret the information flowing on the link as a bit stream. The layer may include, for example, specifications for bandwidth, bit encoding scheme, error correction codes, signaling protocol, framing format and header information.  
         [0035]     As shown in  FIG. 3 , physical link  309  has start port  307  and end port  308 . Physical link  329  has start port  321  and end port  322 . Data injected into a start port traverses the associated physical link and is ejected at the end port of the link. A physical link is bi-directional, so data injected at either port will be ejected at the other port. Since start port  307  and end port  308  are connected to each other by physical link  309 , physical link  309  forms a communication path between start port  307  and end port  308 . Similarly, since start port  321  and end port  322  are connected by physical link  329 , physical link  329  forms a communication path between those ports.  
         [0036]     Physical links and ports may be interpreted concretely, as physical objects. Physical links  309  and  329  could be, for example, copper or fiber cables and ports  307 ,  308 ,  321  and  322  could be physical connectors at the end of the cable. Also, physical links  309 ,  329  could be wireless connections and the ports  307 ,  308 ,  321  and  322  could be connectors attached to antenna circuitry.  
         [0037]     A further discussion of physical link data is provided in relation to  FIG. 4 .  
         [0038]     Adapter Elements  
         [0039]     As shown in  FIG. 3 , adapter data is generated by analyzing adapter elements  311 ,  316   324  and  338 , also referred to as adapters herein. Adapters perform adaptation, or conversion between layers of a network. Adaptation represents both encapsulation, the encoding of one data stream with another, for example, by adding extra header information, and multiplexing, where several data streams are combined into a single stream. Each adapter has an indexed set of guest ports (user ports) and an indexed set of host ports (provider ports). For example, adapter  338  has guest ports  303 ,  304  and  305 . Guest port  303  has a label A, guest port  304  has a label B and guest port  305  has a label C. Adapter  311  has guest ports  312 ,  313  and  314 , with labels A, B and C, respectively. Adapter  316  has guest ports  317 ,  318  and  319  with labels A, B and C, respectively. Adapter  324  has guest ports  325 ,  326  and  327  with labels A, B and C, respectively. Adapters  302 ,  311 ,  316  and  324  have host ports  306 ,  315 ,  320  and  328 , respectively.  
         [0040]     The adapter elements are configured to perform adaptation or conversion between layers of a network. Each adapter has an associated adapter type. The adapter type determines the layer and label of a host port and a sequence of layers and labels for guest ports. An adapter is labeled with its type, and the layers and labels of its ports must agree with the corresponding layers and labels in the type for the adapter to perform adaptation operations.  
         [0041]     For example, an adapter that has a single guest port and a single host port causes any data stream of the appropriate layer to be injected into the guest port where it is adapted (converted) to the layer of the host port and then ejected. An adapter that has several guest ports and a single host port causes the data streams injected into the guest ports to be multiplexed together and ejected from the host port. Adapters are bi-directional, so they can be used to convert data back from the host layer to the guest layer or layers.  
         [0042]     A communication path can be established by injecting data into a guest port of an adapter, the adapted data is ejected from the host port, traverses a link (or, more generally, another communication path) to another adapter host port, where it is then de-multiplexed, or “unadapted,” and ejected from the guest port with the same label as the first guest port. The adapter types and guest port labels and layers must match in order to establish a communication path. The adapter type determines the layer of a host port and a sequence of layers for guest ports. An adapter is labeled with its type and the layers of its ports must agree with the corresponding layers in the type.  
         [0043]     A further discussion of adapter data is provided in relation to  FIG. 5 .  
         [0044]     Network Elements (Connection Data)  
         [0045]     Network elements,  310   323  and  336 , also referred to as nodes herein, show that connection data can be generated by compiling, or combining, a plurality of links and associated ports, and/or portions of a plurality of links and associated ports, together. Examples of connection data representing a communication path are: port  306  and port  307 ; port  308  and port  315 ; port  320  and port  321 ; and port  322  and port  328 .  
         [0046]     A further discussion of connection data is provided in relation to  FIG. 6 .  
         [0047]     The physical map data  302 , which may be represented as NetML, may include a plurality of network layers, such as, for example, SONET, SDH (Synchronous Digital Hierarchy), IP and ATM. As discussed above, a link or port is characterized by its layer, which is the relevant set of information required to characterize the data flowing on a link. The layer may include specifications for bandwidth, bit encoding scheme, error correcting codes, signaling protocol, framing format, header information or other information and may be viewed as an aggregate.  
         [0048]     For example, a sequence of adaptations allows a layered interpretation of the data actually transferred over a plurality of physical links. Data at a first port may be IP; at a second port the data can be interpreted as IP over ATM; and at a third port, the data can be interpreted as IP over ATM over SONET. The data at a fourth port can be interpreted as the direct encapsulation of IP over SONET.  
         [0049]      FIG. 4  shows an example of a representation of physical link data  400 , which is a component of the physical map data (shown in  FIG. 3  as  302 ). The representation of physical link data  400  is typically an abstraction of the physical link data, described in relation to  FIG. 3 , and represented in a form that can be stored in memory and analyzed, processed and manipulated by a processor, as described herein. The physical link data  400  is, for example, a data structure or matrix that has a field  402  that identifies each of a plurality of physical links, a field  404  that identifies a start port for each physical link, a field  406  that identifies an end port for each physical link and a field  408  that identifies links  309  and  329  as physical links.  
         [0050]     While the example of  FIG. 4  shows that field  402  identifies two physical links ( 309  and  329 ), it should be understood that the number of physical links is a function of the physical map data.  
         [0051]     As shown in  FIG. 4 , physical link  309  (field  402 ) has start port  307  (field  404 ), end port  308  (field  406 ). Physical link  309  is a physical link (field  408 ) because start port  307  is connected to end port  308 .  
         [0052]      FIG. 4  also shows that physical link  329  (field  402 ) has start port  321  (field  404 ) and end port  322  (field  406 ).  
         [0053]      FIG. 5  shows an example of a representation of adapter data  500 , which is a component of the physical map data (shown in  FIG. 3  as  302 ). The representation of adapter data  500  is typically an abstraction of the adapter data, described in relation to  FIG. 3 , and represented in a form that can be stored in memory and analyzed, processed and manipulated by a processor, as described herein. The adapter data  500  is, for example, a data structure or matrix that has a field  502  that stores adapter identification data, a field  504  that stores host port data and a field  506  that stores guest port data, in three sub-fields, A, B and C, that identify a label of the particular guest port.  
         [0054]     As shown in  FIG. 5 , adapter  302  (field  502 ) has a host port  306  (field  504 ) and three guest ports,  303 ,  304  and  305  (field  506 ). Guest port  303  has label A, guest port  304  has label B and guest port  305  has label C. Similarly, adapter  311  has a host port  315  and guest ports  312 ,  313  and  314 , having labels A, B and C, respectively. Adapter  316  has host port  320  and guest ports  317 ,  318  and  319 , having labels A, B and C, respectively. Finally, adapter  324  has host port  328  and guest ports  325 ,  326  and  327 , having labels A, B and C, respectively.  
         [0055]      FIG. 6  shows an example of a representation of connection data  600 , which is a component of the physical map data (shown in  FIG. 3  as  302 ). Connection data  600  represents an association of two physical ports of a physical link or a port of a physical link and a port of an adapter. A port may be connected to another port at the same layer and data ejected from one port is injected into a connected port. The representation of the connection data  600  is typically an abstraction of the connection data, described in relation to  FIG. 3 , and represented in a form that can be stored in memory and analyzed, processed and manipulated by a processor, as described herein. The connection data  600  is, for example, a data structure or matrix that has a field  602  that stores first port data and field  604  that stores second port data. As shown in  FIG. 6 , port  306  is connected to port  307 . Similarly, ports  308  and  315  are connected, ports  313  and  317  are connected, ports  320  and  321  are connected and ports  322  and  328  are connected. This connection data  600  is used to determine communication paths of the physical map data (shown in  FIG. 3  as  302 ).  
         [0056]      FIG. 7  shows an example of a representation of binding data  700 , which is a component of the network map data (shown in  FIG. 2  as  218 ). Binding data  700  is an association between the physical map data (shown in  FIG. 3  as  302 ) and the logical map data (shown in  FIG. 3  as  301 ). The representation of the binding data  700  is typically an abstraction of the binding data represented in a form that can be stored in memory and analyzed, processed and manipulated by a processor, as described herein. The binding data  700  is, for example, a data structure or matrix that has a field  702  that identifies link  332 , start port field  704 , end port field  706 , start port binding field  708  and end port binding field  710 . The binding data associates start port  330  (field  704 ) of logical link  332  to port  304  (field  708 ) and end port  331  (field  706 ) to port  325  (field  710 ). Therefore, in order to establish a communication path corresponding to logical link  332 , the physical map data (shown in  FIG. 3  as  302 ) is analyzed using a verification algorithm to verify that a path exists between port  304 , which is bound to port  330 , and port  325 , which is bound to port  331 .  
         [0057]     Binding data  700  shows that ports  330  and  304  and ports  331  and  325 , respectively, are bound. As shown in  FIG. 3 , data injected into guest port  304 , having label B, is multiplexed, via adapter  302 , with other data streams that are injected at guest ports  303  and  305  and ejected from host port  306 . Host port  306  and start port  307  are connected, as a result of connection data  600 , shown in  FIG. 6 , and the data ejected from host port  306  is injected into start port  307 , traverses physical link  309 , and is ejected from end port  308 . End port  308  and end port  315  are connected, as a result of connection data  600 , shown in  FIG. 6 , and the data is injected into host port  315 , where it is reverse multiplexed, or “unadapted,” by adapter  311  and ejected from guest port  313  (the label B of port  313  matches the label B of port  304 ). The connection data  600 , shown in  FIG. 6 , shows guest ports  313  and  317  are connected and the data is injected into guest port  317 .  
         [0058]     Data from port  317  is multiplexed by adapter  316  and ejected from host port  320 . Connection data  600 , shown in  FIG. 6 , shows that host port  320  is connected to start port  321 . The data traverses physical link  329  and is ejected from end port  322 . The connection data  600 , shown in  FIG. 6 , shows that end port  322  is connected to host port  328 . The data is reverse multiplexed, or “unadapted” by adapter  324  and ejected from guest port  325 . The binding data shows that guest port  325  is associated with port  331  of logical link  332 . Hence, logical link  332  is valid since it has a corresponding communication path through physical map data  302 .  
         [0059]      FIGS. 8A-8C , generally referred to herein as  FIG. 8 , are a flowchart of exemplary steps for a verification algorithm  800 . These steps, or functional features, are shown as blocks and are suitably stored on a computer-readable medium, which can be read by a computer, or other processing device, as described herein. The steps may be program code or a series of manipulations of data. While  FIG. 8  shows steps in a particular sequence, this is for explanation purposes, and it is within the scope of the invention that the specific sequence may be modified as a function of specific applications, program code and design considerations.  
         [0060]     Generally, verification algorithm  800 , which is described using examples used in  FIGS. 2-7 , shows steps to verify that the logical links of logical map data (shown in  FIG. 3  as  301 ) correspond to communication paths of the network using the physical map data (shown in  FIG. 3  as  302 ). The algorithm may function in a parallel processing environment wherein criteria are being analyzed substantially simultaneously or in a serial processing environment, in which the analysis is performed substantially sequentially. While  FIG. 8  shows an example of validating a single logical link it should be apparent to one skilled in the art that the algorithm can be used to verify a plurality of logical links.  
         [0061]     A communication path between two ports X ( 304  of  FIG. 3 ) and Y ( 325  of  FIG. 3 ) exists if: the two ports are the start and end ports of a link; or if ports X and Y are each guest ports of an adapter with identical labels, and there is a communication path between the host ports of the two adapters; or there are two intermediate connected ports, with a communication path from port X to one of the intermediate ports, and from another intermediate port to port Y.  
         [0062]     Step  802  begins the algorithm for verifying whether there is a communication path from a port X ( 304  of  FIG. 3 ) to a port Y ( 325  of  FIG. 3 ), which may be the start and end ports of physical map data that are bound to start and end ports of a logical link to be verified (link  332  of  FIG. 3 ). The physical map data ( 302  of  FIG. 2 ) includes ports, indicated as N, P, Q, R and S, (examples of ports are provided in  FIG. 3  as elements  303 ,  304 ,  305 ,  306 ,  307 ,  308 ,  312 ,  313 ,  314 ,  315   316 , etc.) and adapters T and U (examples of adapters are provided in  FIG. 3  as elements  338 ,  311 ,  316  and  324 ). Step  804  determines whether X (port  304  of  FIG. 3 ) is a start port or end port of a physical link. If so, “yes” line  808  leads to step  842 . Step  842  sets port N to be the other port of the physical link containing port X (port  304  of  FIG. 3 ). Step  846  determines if port N is the same port as port Y (port  325  of  FIG. 3 ). If so, “yes” line  848  leads to step  890 . Step  890  establishes that the logical link with link ports that are bound to ports X (port  304  of  FIG. 3 ) and Y (port  325  of  FIG. 3 ) corresponds to a communication path of the physical map data and the particular logical link is valid.  
         [0063]     If step  846  determines that port N is not port Y (port  325  of  FIG. 3 ), then “no” line  850  leads to step  852 . Step  852  determines whether another port is connected to port N. If so, “yes” line  856  leads to step  858 , which establishes P as the other port connected to port N. Line  860  leads to decision block  876 , which determines whether there is a path from port P to port Y (port  325  of  FIG. 3 ). If so, “yes” line  880  leads to step  890 , which determines that a path exists. If not, “no” line  878  leads back to decision step  852 .  
         [0064]     If decision step  852  determines that there is not another port connected to port N, “no” line  854  leads to step  862 , which determines that a path does not exist, and the logical link does not correspond to a communication path and, therefore, the network data is not valid. Line  864  leads to step  868 , which establishes a reason for the invalidity. The reason generated may identify one or more logical links that do not correspond to a communication path. This reason can identify whether the failure was attributed to link data, connection data, adapter data or a combination thereof. The step of generating a reason is optional and can be omitted.  
         [0065]     Step  870  stores reasons for the failure. Step  872  generates an accumulation of invalid logical links, such as a manifest, or record. This manifest may include the reasons for the invalidity. As a further embodiment, the manifest can optionally be transmitted to an output module or facility.  
         [0066]     Step  874  generates a response, or negative indication, or alert, reflecting the inconsistency. This negative indication may be output to a user device, or display device or may be stored in a remote or local memory. End step  892  ends the algorithm.  
         [0067]     Returning to step  804 , if port X (port  304  of  FIG. 3 ) is not a start port or an end port, “no” line  810  leads to decision step  812 , which determines whether X (port  304  of  FIG. 3 ) is a guest port. If not, “no” line  814  leads to leads to step  862 , which indicates that there is not a communication path from port X (port  304  of  FIG. 3 ) to port Y (port  325  of  FIG. 3 ). If decision block  812  determines that port X (port  304  of  FIG. 3 ) is a guest port, “yes” line  816  leads to step  818 . Step  818  establishes: T (adapter  338  of  FIG. 3 ) to be an adapter containing port X (port  304  of  FIG. 3 ); R (port  306  of  FIG. 3 ) is the host port of adapter T (adapter  338  of  FIG. 3 ); and L (label B of  FIG. 3 ) is the label of guest port X (port  304  of  FIG. 3 ). Decision step  820  determines whether there is another adapter different than adapter T (adapter  338  of  FIG. 3 ). If not, “no” line  822  leads to line  814 , discussed above. If decision step  820  determines that there is another adapter different from adapter T, “yes” line  824  leads to step  826 . Step  826  establishes: U (adapter  311  of  FIG. 3 ) as another adapter different from adapter T; and Q (port  315  of  FIG. 3 ) as the host port of adapter U (adapter  311  of  FIG. 3 ). Decision block  828  determines whether there is a path from host port R (port  306  of  FIG. 3 ) to host port Q (port  315  of  FIG. 3 ) of adapter U (adapter  311  of  FIG. 3 ). If not, “no” line  830  leads to step  826 . If so, “yes” line  832  leads to decision block  834 , which determines whether adapter U (adapter  311  of  FIG. 3 ) has a guest port (port  313  of  FIG. 3 ) with label L. If not, “no” line  836  leads to step  826 . If so, “yes” line  838  leads to step  840 , which establishes N as the guest port (port  313  of  FIG. 3 ) with label L. Step  846 , discussed previously, is reached from step  840 .  
         [0068]     When all of the logical links of a logical map have been validated, or verified, by establishing that each logical link represents a communication path, a match indication is generated. This affirmative indication may be output to a user device, or display device or may be stored in a remote or local memory. If each of the logical links is not valid, the network map data is not valid.  
         [0069]     While  FIG. 8  shows an example of the sequence of steps, it is also an embodiment of the present invention that the sequence may be varied. Various permutations of the algorithm are contemplated as alternate embodiments of the invention.  
         [0070]     As described above, layers and adapter types can be discriminated in the network and these layers and types may be preserved during the manipulations of the present invention.  
         [0071]     It is also a further embodiment of the present invention that the verification algorithm determines a communication path corresponding link as efficiently as possible. For example, as soon as a logical link is verified, processing terminates for that logical link.  
         [0072]     As is known in the art, the methods and apparatus discussed herein may be distributed as an article of manufacture that itself comprises a computer readable medium having computer readable code means embodied thereon. The computer readable program code means is operable, in conjunction with a computer system, to carry out all or some of the steps to perform the methods or create the apparatuses discussed herein. The computer readable medium may be a recordable medium (e.g., floppy disks, hard drives, compact disks, or memory cards) or may be a transmission medium (e.g., a network comprising fiber-optics, the world-wide web, cables, or a wireless channel using time-division multiple access, code-division multiple access, or other radio-frequency channel). Any medium known or developed that can store information suitable for use with a computer system may be used. The computer-readable code means is any mechanism for allowing a computer to read instructions and data, such as magnetic variations on a magnetic media or height variations on the surface of a compact disk.  
         [0073]     It is to be understood that the invention may be practiced with other computer system configurations, including, for example, hand-held devices, multiprocessor systems, microprocessor-based or programmable consumer electronic devices, network PC&#39;s, minicomputers, mainframe computers, and other devices with processing capabilities. The embodiment may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices.  
         [0074]     It is to be understood that the embodiments and variations shown and described herein are merely illustrative of the principles of this invention and that various modifications may be implemented by those skilled in the art without departing from the scope and spirit of the invention.