Abstract:
An intelligent network physical layer management system is provided that includes hardware that tracks the connection of plugs of patch cords in interconnect or cross-connect patching environments. RFID signaling is combined with near-field communication techniques to provide a reliable physical layer management system. In interconnect configurations, RFID tags are associated with switch ports of an Ethernet switch, enabling the system of the present invention to detect patch cord insertion and removal at switch ports and to receive information about the switch ports. In cross-connect configurations, RFID signaling is used to track the connections of patch cords between two patch panels. Systems according to the present invention avoid the problems associated with traditional galvanic connections previously used for tracking patch cord connections. An alternative common-mode system is also described.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 12/911,796, filed Oct. 26, 2010, which claims priority to U.S. Provisional Application No. 61/254,800, filed Oct. 26, 2009, the subject matter of which is hereby incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present application relates to network physical layer management systems, and more particularly to a physical layer management system incorporating radio frequency identification (RFID) modules using near-field coupling techniques. 
       BACKGROUND 
       [0003]    Physical layer management (PLM) systems are of growing interest in the communications industry today due to the growing size and complexity of data centers and enterprise networks. A PLM system provides automatic documentation of the physical layer (for example, a system comprising the patch field and the horizontal cabling) and assists in providing patch cord guidance for moves, adds and changes (MAC&#39;s) to the patch connections within a network. The present invention offers a radio frequency identification (RFID) technique that can improve the physical layer management system. RFID technology can be used to eliminate the galvanic connection between the plug ends of a patch cord and the patch panel(s), as found in prior PLM systems, as well as to provide Ethernet switch connectivity information that reduces the need for additional special hardware on the patch panel, such as non-uniform, specialized ports for acquiring connectivity information. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0004]      FIG. 1  shows views of a physical layer management system for use in an interconnect configuration according to one embodiment of the present invention; 
           [0005]      FIG. 2  is a block diagram showing an embodiment of the present invention for use in a cross-connect deployment; 
           [0006]      FIG. 3   a  is a schematic diagram of a patch cord connection according to one embodiment of the present invention; 
           [0007]      FIG. 3   b  is a block diagram showing connection tracking hardware according to one embodiment of the invention; 
           [0008]      FIG. 3   c  is a side view of patch panel and plug hardware according to one embodiment of the present invention; 
           [0009]      FIG. 4  is a schematic diagram of a patch cord according to one embodiment of the invention; 
           [0010]      FIG. 5  is a schematic diagram of a patch cord according to another embodiment of the invention; 
           [0011]      FIG. 6  shows the result of a frequency domain simulation of two series resonant LC circuits for controlling LEDs; and 
           [0012]      FIG. 7  shows the results of a time domain simulation of LED drive circuitry. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    It is advantageous in the development of physical layer management equipment, to make the components that comprise the system to be as simple and unobtrusive as possible for the user. If the user is required to adopt new and complicated procedures to perform simple tasks such as patch cord moves, additions, or changes, the probability of success of the physical layer management system is decreased. RFID technology offers to reduce the complexity of MAC procedures as well as increase the reliability of the system by removing galvanic connections required by some PLM systems. 
         [0014]    Patch cord MAC procedures are generally performed within an area of the network, termed the patch field, which includes at least one patch panel. In general, there are two approaches to integrating patch panels into a network: interconnect and cross-connect. In an interconnect configuration, as shown in  FIG. 1 , a single patch panel is generally placed between the horizontal cabling of the network and another network element, such as a switch. In an interconnect configuration, the patch field is between the patch panel and the switch. A cross-connect configuration, in contrast, as shown in  FIG. 2 , uses two patch panels between the horizontal cabling and the switch. The patch field in a cross-connect configuration is located between the two patch panels. It is advantageous to design a PLM system that can be adapted for use in interconnect or cross-connect configurations. 
         [0015]    View (A) of  FIG. 1  shows the patch field portion of the physical layer management system  10  in an interconnect configuration, in which a patch panel  22  is located between horizontal cabling  11  and an Ethernet switch  14 . An RJ45 jack  12  within the Ethernet switch  14  (or equivalent managed equipment) is provided with an RFID tag  16 , includes an RFID ID chip and an antenna, embedded in it that can be read via an RFID reader system. A patch cord  18 , which is to provide a connection between the jack  12  in the switch and a jack  20  in the patch panel  22 , has antennas  24  and  26  provided in the plugs  28  and  30  on both ends of a cord  32 . The patch cord  18  allows communication between the RFID tag  16  in the Ethernet switch  14  and a reader  34  in the patch panel  22 . The RFID reader  34  communicates with the antenna  26  via an antenna  36  provided in a jack of the patch panel to which the patch cord  18  is connected. 
         [0016]    The two antennas  24  and  26  in the patch cord  18  are connected to each other via a 5 th  wire pair  38  within the cord  32 . Utilizing a 5 th  wire pair is termed an “out of band” communication technique, because it does not employ any of the “in-band” wire pairs commonly used for Ethernet signaling. In this manner the RFID reader  34  in the patch panel  22  can communicate with the RFID tag  16  embedded in the jacks  12  in Ethernet switch ports. Utilizing the 5 th  wire-pair  38  for communication of PLM information ensures the performance integrity of the remaining 4 wire pairs comprising the Ethernet signal in a copper network. This 5 wire-pair cable configuration strategy will work with unshielded twisted pair (UTP) and shielded twisted pair (STP) cabling systems. 
         [0017]    Preferably, the antennas employed in this scheme do not communicate by the use of electromagnetic waves but rather communicate to the receive antennas using a type of near-field coupling communication. 
         [0018]    The type of information that the RFID tag  16  associated with each switch port may contain includes: RFID number, switch port number, switch number, switch type, rack number, physical location description, provisioning time (which reflects the time that a patch connection between the patch panel and the switch port was completed), etc. When the patch panel  22  communicates with the RFID tags  16  provided in the Ethernet ports to which ports of the patch panel are connected, the panel will have the necessary information to completely document the patch field. Information regarding the patch field can then be transmitted via a management connection to a network management system. 
         [0019]    In order to support high density switch equipment (e.g., 48-port 1-rack-unit switches), the RFID tags should be mounted in such a way as to minimize crosstalk between neighboring RJ45 jacks  12  both horizontally and vertically. Proposed tag locations on the jacks and plugs are shown, respectively, in views (B) and (C) of  FIG. 1 . While embodiments of the present invention are shown with RFID tags  16  provided within Ethernet ports, the RFID tags associated with Ethernet ports may alternatively be provided outside of the ports, for example on a faceplate of the Ethernet switch  14 . 
         [0020]      FIG. 2  shows a plan view of a PLM system  39  according to the present invention for use in a cross-connect configuration. In this configuration, two patch panels  40  and  42  are provided between the horizontal cabling  44  and an Ethernet switch  46 , with the patch field being located between the two patch panels  40  and  42 . Ethernet cables  47  connect the Ethernet switch to the patch panel  40 . In  FIG. 2 , as in  FIG. 1 , only one link from the Ethernet switch  46  to the horizontal cabling  44  is shown, although it is to be understood that systems according to the present invention are applied to network environments having multiple links between pieces of network hardware. In this embodiment, RFID readers  34   a  and  34   b  provided in the patch panels  40  and  42  communicate with one another and resolve the physical connectivity of the patch cords  18  connected between ports of the patch panels  40  and  42 . Antennas  36   a  and  36   b  associated with the ports of the patch panels  40  and  42  communicate with one another via fifth wire pairs  38  provided in the patch cords  18 . The antennas  36   a  and  36   b  respectively communicate via signaling transmitted to and from antennas  24  and  26  in the plugs of the patch cord  18 . 
         [0021]    View (i) of  FIG. 3   a  is a schematic view showing in more detail the components of the patch cord  18 . It is preferable to incorporate light-emitting diodes (LEDs) into the plugs of the patch cord, to facilitate MACs. In the embodiment of  FIG. 3   a ( i ), LEDs  48   a,b  and  50   a,b  are provided within the plugs  28  and  30  of the patch cord  18 . Preferably, the LEDs  48   a  and  50   a  are red and the LEDs  48   b  and  50   b  are green. The LEDs can be illuminated individually or simultaneously, when a communication signal placed on the ninth and tenth wires operates at the resonant frequency associated with each LED. In one embodiment, both plugs&#39; LEDs on each end of the patch cord will illuminate in response to a particular signal, because the LEDs are effectively in parallel. In this embodiment, the patch cord is symmetrical. 
         [0022]    The two sets of LEDs  48   a,b  and  50   a,b  can be made to operate independently by providing multiple resonant frequencies for the LEDs to operate under. For example, the LEDs  48   a,b  in a first plug  28  of the patch cord  18  can illuminate at frequencies F 1  and F 2 , and the LEDs  50   a,b  in the second plug  30  of the patch cord  18  can illuminate at frequencies F 3  and F 4 , and hence the four independent frequencies can be used to control the illumination of the LEDs independently or in groups. Setting different resonant frequencies for the LEDs to respond to can be achieved by changing the values of capacitors  52   a,b  and  54   a,b  and/or inductors  56  and  58 . Reasonable LED frequencies include such values as 80 kHz and 3 MHz (as shown in  FIG. 6 ) while the RFID frequency of 900 MHz allows the adoption of standard components.  FIG. 3   a ( ii ) shows the assignment of different signaling frequencies to the two LEDs  48   a,b.    
         [0023]    The embodiment of  FIG. 3   a,  though described in connection with a copper communication network, can be adapted for use in fiber networks. 
         [0024]      FIG. 3   b  is a block diagram that shows in more detail the hardware used to track patch cords according to one embodiment of the present invention. The patch cord  18  is shown in a simplified view that does not point out the plugs. The antennas  24  and  26  are shown as coil antennas. On the patch panel side of the patch cord  18 , the antenna  26  magnetically couples to the antenna  36  associated with the patch panel port to which the patch cord is connected. Hardware within the patch panel, which comprises the RFID reader  34  as shown in  FIG. 1(A) , includes a reader integrated circuit (IC)  37 , and signal generators  41  and  43  that generate frequencies associated with, for example, red and green LEDs in plugs of the patch cord  18 . The reader IC  37  and the signal generators  41  and  43  are connected to a multiplexor or selector  45 , which provides the required signal to the antenna  36 . The signal then is transmitted down the length of the patch cord  18  to the antenna  24 . The signal is coupled from the antenna  24  to the RFID tag  16  associated with the switch port into which the patch cord  18  is plugged. The RFID tag  16  includes an antenna  17  and an RFID IC  19 . The antenna  17 , which is magnetically coupled to the antenna  24 , transfers information from the RFID IC  19  to the antenna  24 . The information signal then travels the length of the patch cord  18 , through the antennas  26  and  36 , to the reader IC  37 . At that point, the reader IC  37  has received the necessary information about the connection between the patch panel port and the switch port. 
         [0025]    RFID readers for use in patch panels according to some embodiments of the present invention may be RFID readers known in the industry and manufactured by companies such as Texas Instruments and Philips. RFID tags for use with embodiments of the present invention, for example in switch ports, include RFID tags known in the industry and manufactured by companies such as Impinj, Invengo, and Biode. RFID readers for use in embodiments of the present invention may operate at a number of different frequencies (for example, 900 MHz, 13 MHz, 125 kHz, or other RFID frequencies). 
         [0026]      FIG. 3   c  shows additional details of communications hardware used in one embodiment of the present invention. A jack  20  of the patch panel accepts a plug  30  of the patch cord  18 . The antenna  26  of the plug  30  is shown as a coil antenna, as is the antenna  36  associated with the jack  20 . The antenna  36  is connected via an antenna connection  35  to a printed circuit board  33  of the patch panel. This connection may be made independently, or it may be made via a printed circuit board  31  associated with the jack  20 . The RFID reader IC  37  shown in  FIG. 3   b  is preferably located on the patch panel PCB  33 . The antennas shown in  FIG. 3   c  are angled in the drawing for visibility. In a preferred embodiment they will oppose one another along a common centerline. 
         [0027]      FIGS. 4 and 5  show alternative embodiments of patch cords  60  and  62  that make use of common-mode signaling over the standard four wire pairs in copper-based Ethernet systems to provide communication between RFID readers and RFID tags, as well as to provide signaling to illuminate LEDs. In the patch cord  60  of  FIG. 4 , two wire pairs are used to transmit both RFID signals and LED illumination signals, in addition to the standard Ethernet communication signaling. In the patch cord  62  of  FIG. 5 , two wire pairs are used to transmit RFID signals, and two other pairs are used to transmit LED illumination signals. In the embodiment of  FIG. 5 , LED signaling connections (not shown) are provided between the contacts associated with pairs C and D of the patch cord  62  and the port contacts at the patch panel, so that the patch panel can provide signals and power to illuminate the LEDs  48   a,b  and  50   a,b  provided in the plugs of the patch cord  62 . 
         [0028]      FIGS. 6 and 7  show the results of simulations of series resonant LC circuits with their respective drive circuits.  FIG. 6  shows the results of a frequency-domain simulation of two series resonant LC circuits. This simulation indicates that two LEDs can be independently controlled by providing control signals at different frequencies.  FIG. 7  shows the results of a time-domain simulation of two resonant circuits for use in driving LEDs, and further indicates that the LEDs can be properly independently controlled.