Abstract:
Current approaches for determining and identifying whether a correct length of fiber cable is installed between network elements configured to communicate using specific lengths of cable require manual inspection. Such manual inspection may include the use of markers used for visual inspection of cables matching corresponding network elements. An embodiment of the present invention utilizes identifiers unique to cables of various lengths to determine whether a correct length of cable has been installed. Further, embodiments of the present invention determine whether the unique identifier is received by a network device according to a channel mapping corresponding to a unique physical mapping associated with cables of various lengths. The use of the identifiers and channel mappings enable automatic discovery of lengths of cable that are installed between network devices.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Fiber-optic communication is a method of transmitting information from one place to another by sending pulses of light through an optical fiber. The light forms an electromagnetic carrier wave that is modulated to carry information. Because of its advantages over electrical transmission, optical fibers have largely replaced copper wire communications in core networks. 
         [0002]    The process of communicating using fiber-optics involves the following basic steps: creating the optical signal involving the use of a transmitter, relaying the signal along the fiber, ensuring that the signal does not become too distorted or weak, receiving the optical signal, and converting it into an electrical signal. 
         [0003]    Some optical paths include a working path and protection path, and having both paths operational is useful for integrity and reliability of a network. 
       SUMMARY OF THE INVENTION 
       [0004]    An embodiment of the present invention is a method, corresponding apparatus, or corresponding communications system for identifying a length of an installed cable. The embodiment enables a signaling interface to receive an identifier unique for a multi-channel cable of a given length. The embodiment also determines whether an identifier received by the signaling interface matches an identifier expected to be received and reports whether the identifier received matches the identifier expected to be received. 
         [0005]    Another embodiment of the present invention is a method, corresponding apparatus, or corresponding communications system for identifying a length of an installed cable. The embodiment includes a multi-channel cable having a given length. The multi-channel cable is selected from among multiple predefined lengths and has at least two channels with unique physical mapping corresponding to the given length. In addition, the embodiment includes a transmitter module that transmits an identifier on the at least two channels according to a channel mapping. The channel mapping corresponds to the physical mapping for the given length. Further, the embodiment includes a receiver module configured to receive the identifier and determine whether the identifier received matches an identifier expected to be received on the at least two channels according to the channel mapping. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The foregoing will be apparent from the following more particular description of example embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating embodiments of the present invention. 
           [0007]      FIG. 1  is a network diagram of an example embodiment of the invention that illustrates operably interconnected network elements. 
           [0008]      FIGS. 2A-2C  are architectural diagrams of example embodiments of the invention that illustrates multi-channel cables of varied length having a unique physical mapping corresponding to the length of the multi-channel cables. 
           [0009]      FIG. 3  is a network diagram of an embodiment of the present invention that illustrates connection paths between interconnected network elements. 
           [0010]      FIG. 4  is a flow diagram of an embodiment of the present invention that illustrates a method for identifying a length of an installed fiber cable. 
           [0011]      FIG. 5  is a flow diagram of an embodiment of the present invention that illustrates a method for determining whether an installed fiber cable is of correct length. 
           [0012]      FIG. 6  is a flow diagram illustrating a method for reporting the length of an installed fiber cable. 
           [0013]      FIG. 7  is a block diagram of an example embodiment of the present invention that illustrates elements a network device for identifying a length of an installed fiber cable. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    A description of example embodiments of the invention follows. 
         [0015]    Example embodiments of the present invention include methods, apparatuses, and communications system for identifying a length of an installed fiber cable. Fiber optic networks, like any other network, have network latency when delivering traffic from a source to a destination. Network latency is herein defined as a time delay for a signal, such as an optical signal carrying data, to transmit from one network node to another. Usually, to determine network latency, origin and destination points in the network are used to define a network communications path over which the signal traverses. In some cases, network latency may be defined herein as the time it takes a signal to make a full circuit back to an originating point, such as a given node in a ring configuration network of nodes. 
         [0016]    The main premise in network latency is that the time of transmission between an origin and destination should be instantaneous. Of course, there will always be some delay. Even transmission at the speed of light is not instantaneous and can be measured with very precise instruments. 
         [0017]    There are a number of factors that contribute to network latency. These include transmission, propagation, switches or routers, and computer hardware delays. All of these factors are relevant to the overall determination of network latency. In some cases, there may not be a delay the user can notice. However, if network latency increases to an extent it becomes a problem, there are typically options available to adjust the source of the delay. 
         [0018]    In network latency, a transmission medium refers to the medium used to convey transmitted signals. Examples include a phone line, fiber optic lines or wireless connection, and each contributes to the delay, though some contribute more (or less) than others. To help reduce network latency, it may be possible to change the medium to a faster (i.e., less delay-causing) type. 
         [0019]    Propagation delay is difficult to control in network latency. Propagation delay is simply the amount of time it takes for a signal to travel from a source node to a destination node over a medium. Propagation delay may be computed as the ratio between a link length (length of the medium) and the propagation speed over the specific medium. Naturally, the greater the distance, the more delayed the transmission will be from source to destination node. 
         [0020]    In addition, latency in optical networks may occur due to skew between or among optical fibers. Skew in optical fibers may be caused by a number of different reasons. For example, one source of skew in optical fibers is caused by an index of refraction variation from fiber to fiber. Another cause of skew in some optical links is due to the physical length difference in fibers in the cable or due to an incorrect cable length. 
         [0021]    Certain switches in an optical network are configured to operate with specific lengths of optical cables, and, thus, specific lengths of fiber. Incorrect installation of an optical cable may cause network transmission problems. For example, the network may drop traffic due to congestion caused by the incorrect installation. However, when attempting to correct the transmission problems, network administrators often first look to errors that are traffic-related on the physical layer, such as errors in transmitting, receiving, buffer settings, and other well known traffic-related errors found through readily available trouble-shooting procedures. In contrast, network administrators currently have no way of automatically determining whether a correct length optical cable has been installed. Thus, network administrators rarely check for such an error, which can lead to days, weeks, or months of trouble shooting from a system level investigation, which means that personnel and path availability are not handling other, more profitable, activities during the troubleshooting. 
         [0022]    One naïve approach to prevent incorrect cable installation is to color code interconnect elements (e.g., network switches and transceivers) and their associated cables. For example, a 10 meter cable may be manufactured with a red color band to match a 10 meter transceiver manufactured with a red color band. However, this approach requires logical coordination of resources, such as internal or external cable manufacturing groups. For instance, color coding requires greater management of piece-part inventory. In addition, the cost of the inventory increases. Further, incorrect installation may still occur due to human error, during installation or incorrect color coding during system or cable assembly processes. 
         [0023]    Embodiments of the present invention relate to automatically identifying a length of an installed fiber cable. An embodiment of the present invention is a method, corresponding apparatus, or corresponding communications system for identifying a length of an installed cable. The method includes enabling a signaling interface to receive an identifier unique for a multi-channel cable of a given length. The method further includes: determining whether an identifier received by the signaling interface matches an identifier expected to be received, and reporting whether the identifier received matches the identifier expected to be received. 
         [0024]    The multi-channel cable with the given length may be selected from among multiple predefined lengths and may include at least two channels with unique physical mapping corresponding to the given length. 
         [0025]    The method may further include enabling a physical interface configured to couple with the multi-channel cable and transmitting an identifier on the at least two channels via the physical interface according to a channel mapping, the channel mapping corresponding to the physical mapping for the given length. The channel mapping may also correspond to the physical interface, signaling interface, or a combination thereof. 
         [0026]    Further, the method may also include enabling the signaling interface to employ a unique identifier for each channel of the multi-channel cable. In addition, transmitting an identifier may further include employing a unique identifier for each channel of the multi-channel cable. 
         [0027]    The method may include enabling the signaling interface to receive a unique identifier for the at least two channels and to receive a common identifier for at least a subset of additional channels. In addition, transmitting an identifier may further include transmitting a unique identifier for the at least two channels and transmitting a common identifier for at least a subset of additional channels. 
         [0028]    The signaling interface may be enabled to receive the identifier via a logical signal. In addition, transmitting the unique identifier may further include transmitting the unique identifier via a logical signal. 
         [0029]    Determining whether the identifier received matches the identifier expected to be received may include determining whether the identifier received on the at least two channels of the multi-channel cable matches a channel mapping, wherein the channel mapping corresponds to the physical mapping for the given length. In addition, a table of channel mappings corresponding to respective predefined lengths may be accessed to determine whether the identifier received matches the identifier expected to be received. Further, the multi-channel cable may be an optical cable. 
         [0030]    The method may also include identifying a discrepancy between the identifier received and the identifier expected to be received and reporting to a craftsperson that the multi-channel cable is an incorrect length, a correct length of cable to install, or that a port to which the cable is coupled is an incorrect port. In addition, upon identifying a discrepancy between the identifier received and the identifier expected to be received, the method may disable initialization of communications traffic via the multi-channel cable. 
         [0031]    An apparatus and communications system corresponding to the above-described embodiments of an example method are contemplated within the scope of embodiments of the present invention. 
         [0032]      FIG. 1  is a network diagram of an example embodiment of the invention that illustrates operably interconnected network elements. The network elements include a transmit module  110  and a receive module  120  interconnected by a bi-directional multi-channel cable  140  via a physical interface  113  of the transmit module  110  and a physical interface  123  of the receive module  120 . Both the transmit module  110  and the receive module  120  are configured to communicate via a bi-directional multi-channel cable  140  of a given length. The bi-directional multi-channel cable  140  may be an optical cable. 
         [0033]    Further, the receive module  120  is also connected to a reporting module  130 . The connection between the receive module  120  and the reporting module may be a wired or wireless connection. Although the reporting module  130  is illustrated as a separate apparatus, the reporting module  130  may be implemented in either the transmit module  110  or receive module  120  via hardwired circuitry or logical interface. 
         [0034]    The reporting module  130  is configured to communicate a reporting message  149  using a local wireless (or wired) protocol, such as Bluetooth®, to a computer  160 . In addition, the reporting module  130  is also configured to communicate the report message  149  using a remote access protocol, such as a Wireless Fidelity (WiFi) protocol using IEEE 802.11, for example, via a base transceiver station (not shown) in accordance with an example embodiment of the present invention. The reporting module may communicate the report message  149  to the base transceiver station or to other wired or wireless devices via the base transceiver station. Wireless devices may include cell phones, smart phones, and personal digital assistants (PDAs). 
         [0035]    In this example, the transmit module  110  includes a signaling interface  170  operably connected to the physical interface  113 . The signaling interface  170  may be a logical interface. Further, the transmit module includes a data store  115 , processor  118 , and a determination module  180 . The transmit module is configured to interconnect with the receive module  120  via the bi-directional cable  140  of a given length. Further, the bi-directional cable  140  of the given length is configured to have a physical mapping corresponding to the given length. The physical mapping of the bi-directional cable  140  may be a unique configuration of channels within the cable. For example, the cable may have multiple channels or optical fibers organized in a manner unique to the given length. For instance, several channels of the cable may be swapped as described below in reference to  FIGS. 2A-2C . 
         [0036]    As stated above, the transmit module  110  is configured to operate with a cable of specific length. Upon installation of the bi-directional cable  140 , the transmit module  110  begins initialization procedures by first determining whether a correct bi-directional multi-channel cable  140  has been installed. The signaling interface  170  accesses the data store  115  via processor  118  to obtain an identifier unique to the bi-directional cable  140  of a given length that should be installed. In addition the identifier, the signaling interface  170  obtains a channel mapping corresponding the physical mapping of the bi-directional cable  140  of a given length that should be installed. The data store  112  includes a table that associates cable lengths with the identifier unique to the cable length and associated channel mappings. 
         [0037]    Upon retrieving the identifier associated with the bi-directional cable  140  that should be installed and the channel mapping, the signaling interface  170  transmits the identifier via a communications message  145  to the receive module  120 . The signaling interface  170  transmits the identifier on at least two channels of the multi-channel bi-directional cable  140  according to the channel mapping that corresponds to a physical mapping for the given length of the multi-channel bi-directional cable that should be installed. For example, the identifier unique to the bi-directional cable  140  of a given length that should be installed in transmitted via the communication message  145  over selected channels of the bi-directional cable according to the channel mapping. 
         [0038]    As stated above, the receive module  120  is also configured to operate with the same bi-directional cable  140  of a given length as the transmit module  110 . Upon receiving the identifier via the communications message  145 , the signaling interface  175  of the receive module  120  monitors the channels on which the communication message  145  is received. 
         [0039]    The determination module  185  receives the communication message  145  and information related to the channels on which the communication message  145  is received from the signaling interface  175 . The determination module  185  then accesses the data store  125  having a table of identifiers unique to cables of a given length associated with the cables of a given length and the channel mapping associated with a physical mapping of the cables of a given length. In addition, the data store  125  includes information regarding the specifications of the transmit module  110  and receive module  120  including an identifier that is expected to be received. The identifier expected to be received is based on a given length of cable the modules are configured to operate with. The determination module  185  determines whether the received identifier matches the identifier expected to be received. In addition, the determination module  185  determines whether the received identifier is received via channels of the cable corresponding to a channel mapping of a multi-channel cable that should be installed. If both math, then the determination module determines that the correct length of cable has been installed and reporting module  130  sends a reporting message  149  to a local computer  160  and/or a remote station via a base transceiver station. 
         [0040]    Alternatively, if the identifier is not received on the correct channels according to the channel mapping corresponding to the cable of a given length, then the determination module  185  determines that an incorrect length of cable has been installed and reporting module  130  reports the incorrect installation. In addition, determination module may also identify the incorrect length of cable that is installed by matching the channels on which the communication message  145  is received to a table held in the data store  125  that associated channel mappings to cables of given length. The reporting module  130  may also report the length of incorrect cable that is installed. 
         [0041]    It should be noted, that an identifier unique for a multi-channel of a given length may not be used. The transmit module  110  and receive module  120  may match the channels communication messages  145  are transmitted and received on and match the data to a channel mapping corresponding to the physical mapping of cables of a given length. Thus, if the channels on which the communication messages  145  are transmitted and received on match the channel mapping, the determination module  185  determines a correct length of cable is installed. Conversely, if it does not match, then the determination module  185  determines that in incorrect length of cable is installed and may determine the length of cable that has been installed by referring to a table of channel mappings associated with cables of given lengths in data store  125 . 
         [0042]    Further, it should be noted that although  FIG. 1  illustrates the use of a multi-channel bi-directional cable, cables of any type may be implemented. For example, if the cable does not have multiple channels with unique physical mappings corresponding to different lengths of cable, the transmit module  110  and receive module  120  may identify the length of cable using only the identifier unique to a cable length. For example, as stated above, different transmission mediums (e.g., copper wire and optical fibers) transmit data at varying speeds. The transmit module  110  and receive module  120  may be configured to determine the speeds at which the identifier is received. For example, the identifier unique to a cable of given length is assigned a constant time of travel associated with the cable of given length. 
         [0043]    Upon transmitting the identifier, the transmit module  110  may attach a transmit time stamp to the identifier. Further, upon receiving the identifier, the receive module  120  may attach a receive time stamp to the identifier. The determination module  185  then calculates the time of travel (i.e., latency) of the identifier as a difference between the receive time stamp and transmit time stamp and matches the time of travel to the constant time of travel. If the travel times match the determination module  185  determines that a correct length of cable is installed. If the travel times do not match, the determination module  185  determines that an incorrect cable has been installed. In addition, the determination module  185  may also match the time of travel to a table of constant time of travels associated with given lengths of cable to determine the length of cable that is installed. 
         [0044]      FIGS. 2A-2C  are schematic diagrams of an example embodiment of the invention that illustrates multi-channel cables of varied length having a unique physical mapping corresponding to the length of the multi-channel cables. 
         [0045]      FIG. 2A  illustrates a 10 meter bi-directional multi-channel cable according to an example embodiment of the present invention. The cable has 24 channels of which 12 of the channels are transmit channels  205   a  and 12 of the channels of receive channels  205   b . As illustrated, the 10 meter cable has a unique physical mapping wherein channel  2   212  and channel  3   213  of the transmit channels  205   a  are swapped. In addition, channels  2   212  and channels  2   213  of the receive channels  205   b  are swapped. Thus, referring to the description of  FIG. 1 , if communication messages  145  are transmitted from transmit module  110  via channel  2   212  from the transmit channels  205   a  of the 10 meter bi-directional cable, the communication messages  145  should be received by receive module  120  on channel  3   213  of the bi-directional cable  140 . 
         [0046]      FIG. 2B  illustrates a 20 meter bi-directional multi-channel cable according to an example embodiment of the present invention. The 20 meter cable has 24 channels of which 12 of the channels are transmit channels  205   c  and 12 of the channels of receive channels  205   d . As illustrated, the 20 meter cable has a unique physical mapping wherein channel  4   214  and channel  5   215  of the transmit channels  205   c  are swapped. In addition, channels  4   214  and channels  5   215  of the receive channels  205   d  are swapped. 
         [0047]      FIG. 2C  illustrates an 80 meter bi-directional multi-channel cable according to an example embodiment of the present invention. The 80 meter cable has 24 channels of which 12 of the channels are transmit channels  205   e  and 12 of the channels of receive channels  205   f . As illustrated, the 20 meter cable has a unique physical mapping wherein channel  5   215  and channel  6   216  of the transmit channels  205   e  are swapped. In addition, channels  5   215  and channels  6   216  of the receive channels  205   f  are swapped. 
         [0048]    It should be noted that any of the channels illustrated in  FIGS. 2A-2C  may swapped to create a unique physical mapping for cables of a given length. In addition, any length of cable may used, with each length of cable having a unique physical mapping. 
         [0049]      FIG. 3  is a network diagram of an embodiment of the present invention that illustrates connection paths between interconnected network elements. A network element  300  includes multiple Universal Fabric Packet High Capacity Switch Shelves (HCSS)  360   a - c . Each shelve may be configured for optical communications via optical shelf interconnects and optical fibers. Further, each shelf  360   a - c  includes transmit modules  310   a - b . The transmit modules  310   a - b  may be fabric element switches. Each transmit module  310   a - b  is operably connected to optical shelf interconnects (OSI)  380 . Further, each transmit module  310   a - b  terminates at three OSIs. Each OSI  380  may have 24 channels that include 12 transmit channels and 12 receive channels, with each channel mapped to the same transmit module  310   a - b . The OSIs  380  are linked to OSIs  385  of an HCSS mate  370  that is configured to communicate with the HCSS  360   a - c . The OSIs  380  are linked to OSIs  385  via bi-directional multi-channel cables  340   a - c . Each cable may be of varying length based on the operating parameters of respective transmit modules  310   a - b  and receive modules  330   a - d  as discussed above in reference to  FIG. 1 . For example, cables  340   a - c  may be 10 meters, 20 meters, or 80 meters in length. Further, the HCSS mate  370  includes receive modules  320   a - d . The receive modules  320   a - d  are operably connected to OSIs  385 . In this example embodiment. The HCSS mate  370  has four receive modules  320   a - d , which employ a mesh connection to the OSI devices  385 . Each of the OSI devices has 12 bi-directional channels split between the four receive modules  320   a - d . Thus, each OSI device  358  is connected to the four receive modules via three bi-directional channels per receive module  320   a - d.    
         [0050]    The transmit modules  310   a - b  and receive modules  330   a - d  are configured to validate the link connections (i.e., cable length) of the link between OSIs  380  and OSIs  385 . The bi-directional cables  340  are configured to have a physical mapping corresponding to the length of the cable. The physical mapping of the bi-directional cables  340  may be a unique configuration of channels within the cable. For example, the cable may have multiple channels or optical fibers organized in a manner unique to the given length. For instance, several channels of the cable may be swapped as described above in reference to  FIGS. 2A-2C . 
         [0051]    As stated above, the transmit modules  310   a - b  are configured to operate with a cable of specific length. Upon installation of the bi-directional cables  340   a - c , the transmit module  110  begins initialization procedures by first determining whether a correct bi-directional multi-channel cables  340   a - c  have been installed. The transmit modules  310 -B obtain an identifier unique to the bi-directional cable  340   a - c  of a given length that should be installed. The length of cable that should be installed is based on operating parameters of the transmit modules  310   a - b  and corresponding receive modules  320   a - d . In addition to the identifier, the transmit modules  310   a - b  obtain channel mappings corresponding to physical mappings of the bi-directional cables  340   a - c  of a given length that should be installed. The identifier and channel mappings may be obtained via a data store operably connected to the transmit modules  310   a - b  or receive modules  320   a - d.    
         [0052]    Upon retrieving the identifiers associated with the bi-directional cables  340   a - c  that should be installed and the channel mappings, the transmit modules  310   a - b  transmit the identifier via a communications message to the receive module  320   a - d . The communication message is first sent to OSIs  380  via links  355   a - f . The OSIs  380  then transmit the communication message over the bi-directional cables  340   a - c  corresponding to channel mappings corresponding to each cable of a given length that should be installed. For example, the communication message with the identifier is transmitted on at least two channels of the multi-channel bi-directional cables  340   a - c  according to the channel mapping that corresponds to a physical mapping for the given length of the multi-channel bi-directional cables  340   a - c  that should be installed. 
         [0053]    As stated above, the receive module  120  is also configured to operate with the same bi-directional cable  140  of a given length as the transmit module  110 . Upon receiving the identifier via the communications message  145 , the receive modules  320   a - c  monitor the channels on which the communication message  145  is received and determine, based on the identifier and channel mappings, whether a correct cable has been installed. 
         [0054]      FIG. 4  is a flow diagram of an embodiment of the present invention that illustrates a method  400  for identifying a length of an installed fiber cable. At  405  the method begins. At  410 , a multi-channel cable if a given length is selected and installed. At  415 , an identifier unique to a multi-channel cable of a given length that should be installed is transmitted across two channels of the multi-channel cable according to a channel mapping corresponding to a physical mapping of a multi-channel cable of the given length. At  420 , the identifier is received, and a determination is made as to whether the identifier matches an identifier expected to be received according to the channel mapping. At  425 , the method ends. 
         [0055]      FIG. 5  is a flow diagram of an embodiment of the present invention that illustrates a method  500  for determining whether an installed fiber cable is of correct length. At  505 , the method  500  begins. At  510 , a multi-channel cable of a given length having at least two channels with a unique mapping corresponding to the length of cable is selected and installed. At  515 , an identifier is transmitted on at least two of the channels according to the channel mapping. At  520 , a determination is made as to whether the received identifier matches an identifier expected to be received according to the channel mapping. If the identifier matches the expected identifier, at  525 , it is reported that a correct length of cable has selected and installed. At  545 , the method ends. 
         [0056]    If, however, the received identifier does not match with the expected identifier, at  530 , a discrepancy between the received and expected identifiers is identified. At  535 , it is reported that the multi-channel cable that was selected and installed is incorrect. The report may include information including at least one of the following: length of the incorrect cable, correct length but incorrectly installed, and a correct length of cable to install. At  540 , initialization of communications via the multi-channel cable is disabled. At  545 , the method ends. 
         [0057]      FIG. 6  is a flow diagram illustrating a method  600  for reporting the length of an installed fiber cable. At  610 , the method  600  begins. At  620 , an identifier is received. At  630 , it is determined whether the received identifier matches an identifier expected to be received. At  640 , it is reported whether the received identifier matches the identifier expected to be received. At  650 , the method  600  ends. 
         [0058]      FIG. 7  is a block diagram of an example embodiment of the present invention that illustrates elements a network device  720  for identifying a length of an installed fiber cable. 
         [0059]    A network device  720  is configured to receive communications via a bi-directional cable  740  of a given length based on the operating parameters of the network device. Before communications may begin, the network device  720  determines whether a correct bi-directional multi-channel cable  740  of a given length is installed to a physical interface  723 . The network device  720  makes this determination based on a communication message  745  including an identifier. The identifier is unique for a multi-channel cable of a given length. 
         [0060]    Upon receiving the identifier via the communications message  745 , a signaling interface  775  of the network device  720  monitors the channels on which the communication message  745  is received. A determination module  785  receives the communication message  745  and information related to the channels on which the communication message  745  is received from the signaling interface  175 . The determination module  785  then accesses the data store  725  having a table  745  of identifiers unique to cables of a given length associated with the cables of a given length and the channel mapping associated with a physical mapping of the cables of a given length. In addition, the data store  725  may include information regarding the specifications of the network device  720  including an identifier that is expected to be received. The identifier expected to be received is based on a given length of cable the network device  720  is configured to operate with. The determination module  785  determines whether the received identifier matches the identifier expected to be received. In addition, the determination module  785  determines whether the received identifier is received via channels of the cable corresponding to a channel mapping of a multi-channel cable that should be installed. If both math, then the determination module determines that the correct length of cable has been installed and reporting module  730  sends a reporting message of the correct installation. 
         [0061]    Alternatively, if the identifier is not received on the correct channels according to the channel mapping corresponding to the cable of a given length, then the determination module  785  determines that an incorrect length of cable has been installed and reporting module  730  reports the incorrect installation. In addition, determination module  785  may also identify the incorrect length of cable that is installed by matching the channels on which the communication message  745  is received to the table  745  that associates channel mappings to cables of given length. The reporting module  730  may also report the length of incorrect cable that is installed. 
         [0062]    Embodiments or aspects of the invention may be implemented in hardware, firmware, or software. If implemented in software, the software may be implemented in any software language capable of performing the embodiment(s) of the invention. The software may be stored on any computer-readable medium, such as RAM, ROM, CD-ROM, and so forth. The software includes instructions that can be loaded and executed by a general purpose or application specific processor capable of supporting embodiment(s) of the invention. 
         [0063]    While this invention has been particularly shown and described with references to example embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.