Abstract:
Method and system for acquiring and updating the topology of a modular scanning system, in which patch panels are scanned. The result of the scanning of each panel is forwarded to a memory cell of an expander. The output of each expander is forwarded to a cell of a successive expander, and so forth, until the output of a final expander is forwarded to a master. Each scanning unit forwards unique ID data to an expander, to which said scanning unit is connected. The unique ID data is relayed from the expander to higher level expanders, all of which are connected in series with respect to one another, until reaching a second level expander, from which the ID data is forwarded to the master where it is stored. This process is repeated while the ID data replaced with neighbors&#39; data, for allowing the master to know which scanning unit is connected to which scanning unit. Finally, the topology map is generated in the master from the collection of ID data and neighbors&#39; data stored therein.

Description:
RELATED APPLICATION  
       [0001]     This application is a continuation of International Application No. PCT/IL04/000864 filed Sep. 20, 2004, which is here incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to the field of cabling systems. More particularly, the present invention relates to a modular scanning system capable of handling small to large scale cabling systems). The present invention relates also to a method for automatically identifying each component within the aforesaid modular scanning system, including its relative location within the topology of the aforesaid modular scanning system.  
         [0004]     2. Prior Art  
         [0005]     The term ‘managing’ (i.e., in connection with ‘management of cabling systems’, or ‘communication panels’, or ‘patch panel’) encompasses operations such as obtaining actual or desired, and/or monitoring the, connectivity status, or map, of a cabling system, and using desired connectivity status for guiding an operator through desirable cabling changes and indicating to the operator erroneous and unauthorized connections and disconnections of patch cords.  
         [0006]     The term ‘Patch Panels’ refers to panels that include data and/or video/voice ports (hereinafter, briefly, “ports”), to which multiconductor cables (hereinafter referred to as ‘Patch Cords’) may be connected, for connecting between any two ports.  
         [0007]     ‘Connectivity Status’, or ‘Connectivity Map’, is an ensemble of data that indicates which patch cord&#39;s end is connected to which port in which patch panel. The connectivity status/map is normally contained within a storage array, for example, in a database.  
         [0008]     ‘Connectivity status indicator’ is an indicator, usually a light source (e.g., LED), that is located in proximity to a port. This indicator will be activated by a central management system in order to mark, or signal (to, e.g., a technician) the port in cases where that port is involved in wanted, or unwanted, connectivity changes.  
         [0009]     The term ‘Scanning System’ refers to a system for associating a first set of ends of patch cords to a corresponding second set of ends of patch cords. This could be obtained for example by transmitting Scanning Signals via the first set of ends of patch cords, and receiving the forwarded Scanning Signals via the second set of corresponding ends of patch cords. The scanning system may contain a database, the content of which is a data representing the connectivity status, or connectivity map, of the scanned cabling system, and updated according to the transmission of the Scanning Signals. A major component in a scanning system is a Scanner, which forwards the scanning signals, interprets the received scanning signals and generates a corresponding connectivity status. A scanning system is described, for example, in U.S. 60/251,444 (“System for automatically identifying the physical location of network end devices”), in co pending Israeli Patent application No. IL 152768 (“Retrofit kit for interconnect cabling system”), and in U.S. Pat. No. 5,483,467 (“Patching panel scanner”).  
         [0010]     By ‘structural change in a cabling system’ it is meant the addition or subtraction of ports to/from a cabling system.  
         [0011]     Big organizations usually have large information systems that are supported by large scale cabling systems. Large cabling systems could include thousands of patch cords that are connected to several dozen patch panels. Normally, a cabling system comprises a plurality of communication panels, each of which comprises several patch panels, preferably structurally connected to form vertical structures, a plurality of patch cords, which carry information (e.g., data, audio, TV signals, etc.), being connected to patch panels. The communication panels allow flexibility in routing information from signals sources to different final users.  
         [0012]     Some organizations might be very small, medium sized, large sized, etc., and so are their cabling systems. Therefore, it is a purpose of this invention to provide a scanning system that allows managing and controlling a cabling system of essentially any size. Other organizations are dynamic in the sense that they are subjected to changes, which changes could be accompanied by corresponding structural changes in their cabling systems. Therefore, it is another purpose of this invention to provide a scanning system that could be easily and conveniently adapted to cope with structural changes in a cabling system.  
         [0013]     Other objects and advantages of the invention will become apparent as the description proceeds.  
       SUMMARY OF THE INVENTION  
       [0014]     The present invention provides a modular scanning system that is capable of being adapted to a cabling system of essentially any size. The present invention provides also a modular scanning system that is scalable, for allowing coping with any structural changes in a cabling system. The present invention relates also to a method for automatically identifying each component within the aforesaid modular scanning system, including its relative location in the topology of the aforesaid modular scanning system, which topology is automatically updated whenever a new/existing component is connected/disconnected to/from the modular scanning system.  
         [0015]     Several additional terms, useful for understanding the invention, will now be defined.  
         [0016]     The term ‘cabling site’ (or, briefly, ‘site’) used herein is an administrative term referring to one patching area, meaning that any port in a specific site could be interconnected with any other port belonging to the same specific site, but not with a port belonging to a an other site.  
         [0017]     By ‘Master’ it is meant hereinafter a component of the modular system, the function of which is coordinating exchange of connectivity data between one or more scanners and a central management system. The master communicates data from the central management system to scanners, for signaling to an operator which ports are involved in wanted connectivity changes and for causing the scanners, whenever required, to initiate scanning sessions, for obtaining current connectivity status of the cabling system. The master also communicates data in the opposite direction, as it communicates the connectivity status from the scanners to the central management system, where the connectivity status is interpreted and a connectivity map is updated, or regenerated. The Master also communicates other types of control messages and responses between scanners and the central management system. Each Master includes one input port, which could be connected to the central management system either directly or via a data network, such as the Internet. The Master provides substantially any required number of output ports, for allowing handling as many as required cabling sites (i.e., one port being dedicated for one site). The master can communicate with the central management system, for example, via a LAN (Local Area Network), using SNMP (Simple Network Management Protocol) protocol. However, other communication arrangements and protocols could be utilized as well.  
         [0018]     By ‘Expander’ it is meant hereinafter a component of the modular system, the function of which is to allow enlarging the number of ports in a cabling site, by cascading Expanders from the corresponding Master, in a manner that is basically hierarchical. One Expander might be connected to one or more Scanners, to one or more Expanders, or to a combination of Expanders and Scanners.  
         [0019]     A large scale cabling system could be administratively (i.e., for management convenience reasons) divided into several sites, in which case the modular scanning system might include one Master, as many Expanders as sites (i.e., one Expander per site), and corresponding number of scanners, for scanning ports in patch panels that are connected to the respective scanners. Alternatively, the large scale cabling system can be handled as one cabling site, in which case only one Master-Expander is to be utilized.  
         [0020]     By ‘scanning unit’ it is meant hereinafter any expander, scanner, indicator controller, and possibly other element that is part of the modular scanning system. Each scanning unit includes means, such as a silicon serial number chip manufactured by Dallas Semiconductors, for making it uniquely identifiable by another Expander. By ‘indicator controller’ is meant a controller that forwards signals to master indicators, the function of which is to indicate to, e.g., a technician, the communication panel(s) in which one or more connectivity status indicators, related to ports of patch panels, are in active mode.  
         [0021]     The term ‘level’ refers to the relative location of each scanning unit in the topology of the modular scanning system. More specifically, by ‘level’ is meant hereinafter the location of each one of the Expanders relative to one another and relative to the Master that monitors and controls their operation. An Expander that is connected to an output port of the Master, is regarded as first level expander. If several Expanders are connected to respective output ports of the same Master, all of these Expanders are referred to as “first-level Expanders”. Likewise, an expander is regarded as a second level expander if it is connected to a first level expander. An Expander may communicate with the Master, via one or more Expanders belonging to higher levels (‘more’—two or more Expanders connected to each other in series). Each Scanner that is connected to an Expander belongs to the level of this Expander.  
         [0022]     By ‘Dallas Chip’ it is meant herein a general name for silicon serial number integrated circuit made by Dallas Semiconductor or other companies. Each chip has a unique factory etched serial number, which allows its unique identification, and, after having such chips incorporated into scanning units and possibly into Patch panels, it allows to distinguish between the scanning units and to uniquely identify each element and patch panel. Utilizing a silicon serial number chip is an option, as the unique ID can be generated by utilizing alternative methods as well, for example, by using unique resistive combinations as identifiers.  
         [0023]     The present invention provides a method for automatically generating a map in the Master that represents the topology of a modular scanning system monitored and controlled by the master, and updating the aforesaid map.  
         [0024]     The apparatus of the invention is a modular scanning system comprising at least one site and preferably a plurality of sites, each site comprising 
        a) a plurality of scanners, each for scanning a plurality “x” of patch panels;     b) a plurality of first expanders, each receiving the output of “y” scanners;     c) optionally, a succession of pluralities of expanders, each receiving the output of expanders of the preceding succession;     d) a final expander, receiving the output of the expanders of the last of said succession, the output of said last expander being the output of the site;        
 
         [0029]     The modular scanning system further comprising a master, receiving in succession the output of all the sites and being capable of drawing a map of the system and of updating it.  
         [0030]     Typically, the expanders of each of said succession are in the number of 8, “y” is 8, and “x” is 24.  
         [0031]     If, for example, the succession of pluralities of expanders comprises 3 pluralities, the expanders of each of said succession are 8, and “x” is 24, the master will receive from each site 3×8×24=576 input values, and the hardware of the corresponding master will be moderate. If each output will be received and registered in, say, 3 seconds, 11520 values will be received and registered by the master in one minute and 100,000 in less than 10 minutes, and in a shorter time if the pluralities of expanders in each site are more than 3. The economy of hardware compared to a master receiving the data concurrently from all panels, is obvious.  
         [0032]     The modular scanning system of the invention, therefore, can be defined more synthetically as comprising, in addition to a number of patch panels and to a master, as hereinbefore defined, a number of sites each comprising a cascade of expanders divided in a plurality of successive levels, the output of a number of expanders in each level being the input of a single expander in the successive level. It is noted that in this definition the succession of levels goes from a first level that is closest to the scanners to a final level that is closest to the master. A succession that is verbally opposite, but substantially the same, in which the level that is closest to the master is called the first and the final level that is closest to the scanners is called the final one, may be used for descriptive purposes, and will be used in an example.  
         [0033]     The invention also provides a method of managing a modular scanning system, in which patch panels are scanned, the result of the scanning of each panel is forwarded to a memory cell of an expander, the output of each expander is forwarded to a cell of a successive expander, and so on, until the output of a final expander is forwarded to a master.  
         [0034]     The modular scanning system comprises the Master, one or more scanning units and patch panels, each of which has a unique ID for distinguishing between the scanning units/patch panels. Knowing the topology map of the scanning system allows the Master to cooperate with the scanning units and patch panel belonging to the site(s) monitored and controlled by this Master, and an updated topology allows the Master to know if one or more new scanning units have been connected, or existing scanning units disconnected, to/from the modular scanning system. The method allows also identifying changes (i.e., connection/disconnection of scanning units) in the topology map.  
         [0035]     Preferably, generating the map of the topology of a modular scanning system is performed by: (a) forwarding, by each scanning unit, unique ID data to the expander to which the scanning unit is connected; (b) relaying the unique ID data from this expander to higher level expanders, all of which are connected in series with respect to one another, until reaching the second level expander, from which the ID data is forwarded to the master where it is stored; (c) repeating steps (a) and (b), with the ID data replaced with neighbors&#39; data, for allowing the master to know which scanning unit is connected to which scanning unit; and (d) generating the topology map from the collection of ID data and neighbors&#39; data stored in the master.  
         [0036]     Preferably, each patch panel in the modular scanning system forwards its unique ID data to the scanner to which it is connected, for notifying the scanner of its existence. Then, the ID data of the patch panel is forwarded from the scanner to the expander to which it is connected, from which expander the ID data is relayed to higher level expanders, until reaching the master, where the ID data is stored.  
         [0037]     Preferably, in each expander there is stored a copy of the ID data of only scanning units that are connected to its output ports. Optionally, each expander keeps a copy of every ID data that is relayed by it to a higher level expander, or to the master.  
         [0038]     The topology map can be updated in two ways: (a) every time a new scanning unit is connected to an existing expander, or to the master, the new scanning unit forwards its ID data to the expander or to the master, in the way describe before; and (b) whenever a scanning unit is disconnected or in inactive mode of operation (i.e., switched to “OFF”) its disconnection, or inactivation, is identified by performing verification process, which comprise: 
        forwarding verification signals from the master to each one of its output ports, each of which is assumed to be connected directly to respective scanning unit. The connected scanning units respond to the verification signals by forwarding acknowledgement signals to the master, thereby notifying the master of their being connected to the master and in active mode of operation; and     for each expander, forwarding verification signals to its output ports, each output port is assumed to be connected to respective lower level scanning unit. Scanning units, which are connected to respective output ports, respond to the verification signals by returning acknowledgement signals to the expander, thereby notifying the expander of their being connected to the expander and in active mode of operation.        
 
         [0041]     Preferably, each scanning unit forwards to an Expander of higher level, or to the master (depending to which the scanning unit is directly connected), to which the scanning unit is directly connected, a data that indicates, to the higher level expander or to the master, which of the lower level scanning units that are assumed to be connected to it, are still connected to it, and which have been disconnected (‘assumed’—according to the topology map that was known from the previous verification session).  
         [0042]     According to one aspect of the present invention, the Master communicates with the scanning units that are connected thereto every predetermined time interval, for making sure that none of them had been switched to inactive mode, or disconnected from the modular scanning system. Failing to receive response, with respect to one or more scanning units, will cause the Master to forward corresponding alert message to the central management system.  
         [0043]     Likewise, each Expander communicates with the scanning units (i.e., Expanders, Scanners), which are directly connected thereto, every predetermined time interval, for making sure that none of them had been switched to inactive mode, or disconnected from the modular scanning system. Failing to receive response, with respect to one or more scanning units, will cause the Expander to forward corresponding alert message to the Master, which will, in turn forward a corresponding message to the central management.  
         [0044]     Likewise, each Scanner communicates with the patch panels, which are directly connected thereto, every predetermined time interval, for making sure of their existence prior to transmission of scanning signals to their ports. Upon identification of mismatches by a Scanner, with respect to one or more patch panels, the Scanner will forward corresponding alert message to the Master, via one or more Expanders or directly, which will, in turn, forward a corresponding message to the central management.  
         [0045]     According to an aspect of the present invention, whenever a new scanning unit is connected to an Expander of an already working modular scanning system, the new scanning unit forwards to the expander data relating to its type and unique ID. The scanning unit keeps forwarding this data every predetermined time interval in order to allow detecting mismatches with respect to the data previously stored in the Expander.  
         [0046]     The present invention provides also a modular scanning system for managing ports of patch panels belonging to a cabling system. The modular scanning system is manageable by a central management system, and it comprises, per cabling site: 
        a) One or more Scanners, to each one of them is connected a patch panel, for obtaining the connectivity status of the ports in each patch panel and controlling these ports continuously, whereby to signal, among other things, by utilizing connectivity status indicators and master indicators, wanted and unauthorized changes in said map, and if a mistake has occurred in changing said status. The Scanners are uniquely identifiable by the central management system, for allowing bidirectional communication between the central management system and the Scanners; and     b) A Master, which intermediates between the Scanners and the central management system. The Master communicates control messages, and optionally other types of data, from the central management system to the Scanners, and connectivity data relating to connectivity status from the Scanners to the central management system, where the connectivity data is interpreted and the connectivity map is updated accordingly, and, whenever an erroneous or unauthorized connection is detected by the central management system, alarm messages are generated and communicated to the Scanners via the Master, and, optionally to other means.        
 
         [0049]     According to one aspect of the present invention, the modular scanning system further comprises an Expander, being a first, or highest, level Expander, that intermediates between the Master and one or more Scanners to which patch panels are connected, and allows, there through, bidirectional communication between the central management system and Scanners, for expanding the monitoring and controlling capabilities of the central management system to a larger number of ports. The first level expander could be connected to additional Expanders that form a second and lower level, etc.  
         [0050]     According to another aspect of the present invention, the modular scanning system further comprises additional one or more Expanders, one of which is connected to the first level Expander and all of which are connected to one another, essentially in hierarchical manner to form essentially two or more levels, wherein one or more Expanders at each level are connected to one or more Expanders at a higher level, and to Scanners to which patch panels are connected, and/or to Expanders at a lower level. Each one of the Expanders is capable of bidirectional communication with, and is uniquely identifiable by, the central management system.  
         [0051]     Preferably, the Master communicates with the central management system via a data network. Alternatively, the Master communicates with the central management system directly; that is, by directly connecting the Master to the central management system.  
         [0052]     According to an aspect of the present invention, the functionalities of the Master and the Expander are combined in a Master-Expander, which Master-Expander is capable of handling one Site that could be as large as required.  
         [0053]     Preferably, each one of the patch panels includes a ‘Dallas chip’ that allows the central management system to uniquely identify individual patch panels, and, thereby, to identify the type and model of each patch panel, in order for the central management system and/or Master to know in addition to the number and order of ports that are included in each one of the patch panels, the exact type of the patch panel (e.g. UTP/STP, etc) and preferably the unique ID of the panel for maintenance capabilities and for generating the topology.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0054]     The above and other characteristics and advantages of the invention will be better understood through the following illustrative and non-limitative detailed description of preferred embodiments thereof, with reference to the appended drawings, wherein:  
         [0055]      FIG. 1  schematically illustrates an exemplary topology of a modular scanning system, according to the present invention;  
         [0056]      FIG. 2  schematically illustrates typical arrangements of scanning units for coping with different requirements of different cabling sites, according to the present invention;  
         [0057]      FIG. 3  illustrates the levels of an exemplary topology, according to the present invention; and  
         [0058]      FIG. 4  schematically illustrates the auto-recognition process, according to a preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0059]      FIG. 1  schematically illustrates a general layout and functionality of the modular scanning system, according to the present invention. Central management system  10  cooperates with one master unit ( 11 ) via data network  10 / 1 . Central management system  10  may communicate with Scanner  17  via Master  11  and Expander  12 , and the communication may include forwarding control messages from the central management system  10  to Scanner  17 , causing Scanner  17 , among other things, to initiate scanning sessions. Each scanning session includes emission of scanning signals from Scanner  17  to ports residing within one communication panel, and receiving scanning signals from corresponding ports in the same, or different, communication panel(s). For example, Scanner  17  may forward scanning signals via channel  17 / 1  (normally a flat cable that connects outputs of a Scanner to patch panels) to the ports of patch panels  14  and  15  that reside within communication panel  16 , and receive scanning signals via the same channel (i.e.,  17 / 1 ) and/or via; e.g., channel  17 / 11  that could be connected to ports residing in the same communication panel (i.e.,  16 ) or in different communication panel(s).  
         [0060]     By utilizing scanning signals, Scanner  17  detects the connectivity status of the ports that are monitored by Scanner  17 , and forwards a data relating to the connectivity status to Master unit  11 , via expander  12 , which, in turn, forwards that data to central management system  10 . Next, central management system  10  updates a connectivity map that is contained in, e.g., a database according to the last connectivity status that was forwarded to central management system  10  by Scanner  17 .  
         [0061]     Scanner  17  is normally capable of monitoring twenty four patch panels, such as patch panels  14  or  15 , each of which having normally  24  ports. However, a Scanner could be designed to monitor different numbers of patch panels/ports. In general, the more patch panels there are in a cabling system, the more Scanners are required. Accordingly, other Scanners, such as Scanner  17 , could be added to the modular scanning system. Reference numeral  18  denotes optional connections of additional Scanners to Expander  12 .  
         [0062]     Optionally, Master unit  11  might distribute control messages, via Expander  12 , to indicator controllers such as indicator controller  13 , for signaling to an operator which communication panels are involved in wanted, or unwanted, connectivity changes. For example, Master  11  may forward a control message for causing indicator controller  13  to forward a signal to master indicator  13 / 1  for signaling to an operator (not shown) that wanted or unwanted connectivity changes were/are made in communication panel  16 .  
         [0063]     More than one Master could communicate with central management system  10 , though only one is shown (i.e.,  11 ). Master unit  11  could be connected to four Expanders (only one is shown,  12 ). Each one of the Expanders could be further connected to eight devices, which could be Scanners, other Expanders, indicator controllers, or some combination thereof.  
         [0064]     Each one of the scanning units (i.e., Masters, Expanders, Scanners and patch panels) includes a “Dallas chip”, for making them uniquely identifiable by central management system  10 . This way, central management system  10  knows the number of the scanning units and the type of each scanning unit in the modular scanning system and the relative location of each scanning unit in the modular scanning system. The latter feature allows central management system  10  to address, on selective basis, specific scanning units.  
         [0065]     Some of the functionality of central management system  10  and Master  11  could be manually and locally (i.e., at close proximity to the Scanner) performed by an operator, by operating a control pad, such as control pad  19 , which is connected to a Scanner such as Scanner  17 . Control pad  19  allows an operator (not shown) to locally interact with the modular scanning system and patch panels. For example, control panel  19  allows an operator to carry out test, maintenance and configuration procedures, with respect to every scanning unit and patch port in the site, including checking the connectivity status indicator of every port in every patch panel. In addition, control pad  19  allows an operator to perform connectivity changes. If the actual modular scanning system includes more than one Scanner, such as Scanner  17 , control pad  19  could be moved from one Scanner to another Scanner, or, alternatively, several control pads could be simultaneously connected to several Scanners, for allowing several operators to independently perform various interactions with the modular scanning system and patch panels (see a description relating to  FIG. 5 ).  
         [0066]     The modular scanning system is scalable, because additional scanners and, if required expanders, can be conveniently added to an existing modular scanning system, to allow the master to handle additional patch panels. Every addition, removing or relocation, of a scanning unit results in automatic updating of the topology in the master.  
         [0067]      FIG. 2  schematically illustrates typical arrangements of scanning units for coping with different requirements of different cabling sites, according to the present invention. Exemplary modular scanning system  20  comprises several scanning units; that is, Master  21 , several Expanders, such as Expander  22 , and several Scanners, such as Scanner  28 , which are arranged for handling several sites, such as Site- 1 . Master  21  includes eight ports (i.e.,  21 / 1  to  21 / 8 ) for allowing it to handle up to eight sites. Only exemplary sites  1 ,  3  and  4  are shown, for illustrating typical modular scanning solutions for different cabling requirements. Site- 4  is the simplest case, because it involves a relatively small cabling system, which requires only one Scanner (i.e.,  28 ). Since exemplary cabling Site- 4  is not likely to have more than 576 ports, there is no need for an Expander, and Scanner  28 , which is capable of handling up to 576 ports, is connected directly to (exemplary port  21 / 4  of) Master  21 . If there is a need to extend the cabling system of Site- 4  (i.e., adding additional ports), one Expander, or several Expanders, could be easily added, as shown in the configuration of Site- 1  or Site- 3 , respectively (i.e., Expander  22 , or  24  and  25 , respectively). Of course, the actual number of the Expanders depends on the actual number of the total ports of the extended cabling site.  
         [0068]     Site- 2 , which is a medium-sized cabling system (i.e., in comparison to Sites- 4  and  3 ), requires one Expander (i.e.,  22 ), to which a maximum of eight Scanners (i.e.,  23 / 1  to  23 / 8 ) could be connected, for allowing handling up to 4,416 ports (i.e., in a case that each Scanner handles  24  patch panel, each including 24 ports).  
         [0069]     Site- 3 , which is the largest cabling system (i.e., in comparison to Sites- 4  and  1 ), requires several Expanders that are arranged in levels. The first, and highest, level Expander (i.e., Expander  24 ) is connected to exemplary port  12 / 3  of Master  21 . Expander  24  includes eight ports to which up to eight additional Expanders (i.e.,  25 / 1  to  25 / 8 ), which form a second level of Expanders, could be connected. To each one of the second level Expanders  25 / 1  to  25 / 8  could be connected up to eight Scanners. For example, to Expander  25 / 1  could be connected Scanners  26 / 1  to  26 / 8 . Likewise, to Expander  25 / 8  could be connected Scanners  27 / 1  to  27 / 8 .  
         [0070]     Master  21  communicate with a central management system, directly or via a data network. Both the central management system and data network are not shown in  FIG. 2 .  
         [0071]      FIG. 3  illustrates the principle of establishment of Expanders&#39; levels, according to the present invention. In order to simplify the description, only scanning units of Site- 1  (i.e., reference numeral  32 ) will be referred to herein below. Exemplary port  31 / 1  of Master  31  is connected to a first level (i.e., the highest level) Expander  33 . Next, to the outputs of Expander  33  could be connected second-level (i.e., lower level) Expanders, such as second-level Expander  34 . To the outputs of second level Expander  34  could be connected as many as eight third-level (i.e., more lower level) Expanders, such as third-level Expanders  35 / 1  to  35 / 8 , which could be eventually connected to corresponding Scanners. Of course, if the size of the cabling system so requires, or there is a need to extend an existing cabling system, additional lower levels of Expanders could be easily and conveniently added to modular scanning system  30 . For example, one or more of the eight Scanners  96  (only one shown,  96 / 8 ), and/or one or more of the eight Scanners  97  (only one shown,  97 / 8 ), and/or one or more of the eight Scanners  98  (only one shown,  98 / 8 ), could be replaced by Expanders, in which case the added Expanders will form a forth-level of Expanders. A level could be considered as a ‘level’ only if it includes at least one Expander. A level may include only Expanders, as is shown with respect to levels 1 and 2 of Site- 1  ( 32 ), or a combination of Expanders and Scanners, as shown with respect to level 3 of Site- 1  ( 32 ).  
         [0072]      FIG. 4  schematically illustrates the auto-recognition principles, according to a preferred embodiment of the present invention.  FIG. 4  shows a simple exemplary topology that will facilitate the understanding of the auto-recognition principles. The exemplary topology includes master  41  and four scanning units  42  to  45 . Scanning units  42  and  44  are expanders, and scanning units  43  and  45  are scanners, to which one or more patch panels can be connected, whose connectivity status is to be monitored and controlled by master  41 , or by a central managing unit that is directly or indirectly connected to master  41  in the way described in connection with  FIG. 1 . As described before, any combination of scanning units can be connected to master  41 . For example, the scanning units can be an expander, such as expander  42 , and a scanner, such as scanner  43 . Master  41  is regarded as the first, and highest, level. Being connected to master  41 , scanner  43  belongs to the first level of master  41 . Expander  42  forms the second level, which is regarded as a lower level with respect to master  41 . Being connected to second level expander  42 , scanner  45  also belongs to the second level. Expander  44  forms the third level because it is connected to the output port (not shown) of a second level expander ( 42 ). Being connected to expander  44 , scanner  46  belongs to the third level expander  44 .  
         [0073]     Each one of the exemplary scanning units  42  to  46  includes a unique ID data that allows, among other things, distinguishing one scanning unit from the other scanning units. The ID data of every scanning unit is forwarded to master  41 , where it stored.  
         [0074]     Each scanning unit forwards its ID data to the expander to which it is connected. This expander relays the ID data to a higher level expander, to which it is connected, and the latter expander relays the ID data to a higher level expander, and so on, until the ID data reaches the second level expander, which forwards the ID data to master  41 . Referring to  FIG. 6 , scanner  45  forwards ( 45 / 1 ) its ID data to second level expander  42 , which relays ( 42 / 1 ) this ID data, and also its own ID data, to master  41 . Scanner  46  forwards ( 46 / 1 ) its ID data to third level expander  44 , to which it is connected, and third level expander  44  relays ( 44 / 1 ) this ID data, and also its own ID data, to second level expander  42 , which forwards ( 42 / 1 ) the ID data of scanner  46  and the ID data of expander  44  and its own ID to master  41 . Scanner  43  forwards ( 43 / 1 ) its ID data directly to master  41 .  
         [0075]     The identification (ID) data contains information such as: (1) Serial number of the scanning unit, (2) operation mode (3) Type of scanning unit, (4) software version, etc.  
         [0076]     Each one of the output ports of each scanning unit might be potentially connected to a lower level scanning unit, and each scanning unit includes a data (herein ‘neighbors’ data’) that specifies if there is any scanning unit that is connected to one of its output ports. The neighbors&#39; data can be obtained automatically, for example, by forwarding, by each scanning unit corresponding inquiry signals to its output ports. Each one of the scanning units then forwards its neighbors&#39; data to master  41 , essentially in the same way it forwards its, and potentially others, ID data to master  41 .  
         [0077]     Based on the collection of ID data and neighbors&#39; data, which are stored in master  41 , master  41  generates topology map of the modular scanning system, after which master  41  ‘knows’ which scanning unit is connected to which scanning unit, how many branches there are in the cabling site, what are the types and serial numbers of the scanning units, etc.  
         [0078]     After the generation of the topology map of the modular scanning system, master  41  is updated with every new scanning unit that is connected to modular scanning system. The new scanning unit (not shown) forwards its ID data to the expander to which it is connected, and this ID data reaches master  41  in the same manner as described before. The topology map is updated by master  41  accordingly.  
         [0079]     If a scanning unit is disconnected, or inactivated, the fact of its disconnection, or inactivation, is forwarded to master  41  as will be described now. Each one of the scanning units  42  to  46  forwards to its output ports inquiry signals, for identifying whether scanning unit, which are assumed to be connected to one of its output ports (‘assumed’ according to last known topology map), are still connected, or, if they are, if they are in inactive mode of operation. For example, expander  42  forwards ( 44 / 2 ) inquiry signal to expander  44 , and also ( 45 / 2 ) to scanner  45 . Likewise, expander  44  forwards ( 46 / 2 ) inquiry signal to scanner  46 . If a scanning unit fails to receive a response at one, or more, of its output ports, the scanning unit notifies that fact to master  41  by relaying to master  41  a corresponding data, via the corresponding expanders, from a lower level expander to a higher level expander. For example, if, for some reason, scanner  46  is disconnected, or switched to inactive mode of operation, expander  44  will not receive a response after forwarding ( 46 / 2 ) the inquiry signal, and will update its neighbors&#39; data. Expander  44  will, then, forwards its updated neighbors&#39; data to master  41 , which can respond by updating the topology map, or by generating alert signal, or both updating the topology map and generating alert signal. As a result of the disconnection/inactivation of scanner  46 , master  41  excludes the (disconnected/inactivated) branch, which includes scanner  46  and patch panels that can be potentially connected to it (not shown), for optimizing the scanning procedure.  
         [0080]     The neighbors&#39; data of each scanning unit can be updated by forwarding the corresponding inquiry signals each predetermined time interval, or according to any preferable criteria.  
         [0081]     The principle of using ID data for obtaining the topology of a modular scanning system can be adapted to modular scanning systems having their scanning units connected in series, in parallel, or alternatively, some of the scanning units of a modular scanning might be connected in series, and the other scanning units might be connected in parallel.  
         [0082]     While some embodiments of the invention have been described by way of illustration, it will be apparent that the invention can be carried into practice with many modifications, variations and adaptations, and with the use of numerous equivalents or alternative solutions that are within the scope of persons skilled in the art, without departing from the spirit of the invention or exceeding the scope of the claims.