Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority to U.S. Provisional Application Ser. No. 60/721,131, entitled “Powered Patch Panel,” filed on Sep. 28, 2005. 
    
    
     BACKGROUND 
     Networks that provide power over network cables are attractive because installing a separate power grid is not required when installing equipment having power requirements that may be met by the network connection. Improvements in inserting power into network cables are needed. 
     SUMMARY 
     A powered patch panel (PPP) is disclosed that is Telecommunication Industry Association (TIA) category 5e and 6 compatible (i.e., supports communications in the gigahertz range), that is compatible with corresponding international standard categories, and that supports power-over-network (PoN) such as power-over-Ethernet (PoE). For example, a PPP may be used in mid-span regions of a network in both cross-connect and interconnect configurations. Thus, the PPP may be incorporated as part of a building permanent link by being directly connected to horizontal cabling. When so incorporated, the building permanent link is category 5e and 6 compliant and may support power-over-network (PoN) such as power-over-Ethernet (PoE). 
     In cross-connect and interconnect configurations that include a patch panel, the PPP may replace the patch panel without requiring additional rack space, provide identical patching flexibility, insert power into network cables, and provide intelligent processing to perform local control and monitoring functions as well as enforcement of network policies. 
     The PPP may include two power supply input ports so that two power supplies may be used in a fault-tolerant manner to power each PPP. Further, PPP electronics may be separated into at least two power-independent portions, each powered by a separately supplied power-plane. Combined power from the power supply inputs may be converted into at least two independent power outputs that supply power to the two power-planes. One of the power-planes may provide power to a common circuit that includes a processor and supporting hardware while the other power-plane may provide power for a port circuit. 
     All communications between circuits of the common circuit and port circuit may be power-isolated by either or both optical couplers or capacitors (power isolators), for example, so that power failure in one power-plane does not result in power failure in the other power-plane. In this way, the port circuit and/or common circuit may perform its functions even in the event of power failure in the other circuit. Thus, fault-tolerance may be achieved at the power-plane level. 
     The PPP may provide powered device (PD) interrogation and power management capabilities. For example, the PPP may detect connection or disconnection of a PD, automatically determine power requirements, and supply power to the PD. Each port may be periodically checked for legacy devices (devices having PoN functionality incompatible with IEEE 802.3af) and accommodated accordingly. In addition, current limiting may be provided for each port. 
     The PPP may provide LED indicators corresponding to each of the ports. LED functionality may include indication of a PD connection, whether a PD is either an IEEE 802.3af compliant device or a legacy device, and a current limiting condition. Further, LEDs may be controlled to assist in moves, additions, and changes of network cable connections by changing color, turning on or off, and/or adjusting blinking rate. 
     Other LEDs may be provided to indicate a PPP status and/or a PPP network connection status. For example, an in-line current manager may determine voltage and current input from one or more power supplies and control a PPP LED to indicate conditions such as that the power consumption threshold has been exceeded, the voltage level input is above or below a particular threshold, or the total current output threshold has been exceeded. LED indicators may be provided for an input and an output network connection port. 
     The input and output network connection ports may support connection of multiple PPPs in a daisy chain configuration. Each of the network ports may be provided with an LED to indicate port status such as connection failure, for example. The daisy chain configuration may provide network connections for devices other than PPPs (such as power supplies) and assist conserving switch port utilization. 
     Each PPP may include a processor to provide local intelligence for monitoring and controlling PPP ports and to interface with one or more network management systems (NMSs) and/or element management systems (EMSs). On installation, local physical address information such as room number, rack number and/or position in the rack may be entered and saved in a non-volatile memory. Physical address information may also be re-entered when a PPP is reconfigured by changing horizontal cable connections, for example. The processor may upload the local physical address information to the NMS/EMS. Additionally, when PDs are either connected or disconnected, the port status in the non-volatile memory may change. These changes, together with any identifying information, may be automatically reported to the NMS/EMS or stored for later retrieval when requested by the NMS/EMS. 
     The NMS may provide overall network control and encompass many network devices, while the EMS may be more locally focused. For example, the EMS may be directed to a single PPP, even though it may have access to all network-connected devices. The NMS/EMS may perform functions such as:
         1. monitoring:
           a. connectivity of the network or a subnet of the network,   b. power consumption status of a PPP,   c. connection status of a particular port of a PPP,   d. power supply status at the PPP and/or at the power supply, and   e. PPP network connection failure,   
           2. transmitting control parameters to the PPP to control:
           a. setting PPP power consumption level,   b. prioritize power for each port with low, medium or high priorities,   c. selectively turning ports on or off based on priorities during power outages or for testing, for example,   d. activating port LEDs to support moves, additions, and changes of connections,   e. download software to a PPP for software update; and   
           3. network policy deployment:
           a. security policy,   b. power consumption and distribution.   
               

     The NMS/EMS may include a graphical user interface (GUI) to assist an operator to control and monitor the network. For example, the GUI may display a topology of the complete network, a portion of the network (subnet), or particular unit types such as PPPs of a subnet, for example. The GUI may display all the PPPs of a particular rack and provide information such as location address, MAC address, power consumption, and/or current limiting status of each port of any of the PPPs. In this way, the operator may view one or more statuses only of devices of interest and can efficiently determine the condition of the network or a subnet of the network. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is described in detail with reference to the following figures wherein like numerals reference like elements, and wherein: 
         FIG. 1  shows an exemplary network system; 
         FIG. 2  shows an exemplary building floor plan; 
         FIG. 3A  shows a first conventional LAN cross-connect configuration; 
         FIG. 3B  shows a second conventional LAN cross-connect configuration; 
         FIG. 4A  shows an exemplary PPP LAN cross-connect configuration; 
         FIG. 4B  shows an exemplary PPP LAN interconnect configuration; 
         FIG. 5  shows an exemplary front perspective view of a PPP; 
         FIG. 6  shown an exemplary rear perspective view of a PPP; 
         FIG. 7  shows an exemplary perspective view of a punch-down block; 
         FIG. 8  shows an exemplary ground strap; 
         FIG. 9  shows an exemplary rear plan view of three PPPs and a power supply installed within an equipment rack; 
         FIG. 10  shows an exemplary PPP input power diode circuit; 
         FIG. 11  shows an exemplary PPP internal Ethernet switch; 
         FIG. 12  shows an exemplary hardware block diagram of a PPP; 
         FIG. 13  shows an exemplary block diagram of a current manager; 
         FIG. 14  shows an exemplary block diagram of a PoE manager; 
         FIG. 15  shows an exemplary block diagram of an LED manager; 
         FIG. 16  shows an exemplary PD detection flow chart; 
         FIG. 17  shows an exemplary legacy device detection flow chart; 
         FIG. 18A  shows an exemplary legacy powered device detector and connected legacy device; and 
         FIG. 18B  shows an exemplary polarity reverse switch. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       FIG. 1  shows an exemplary network system  100  that supports PoN, such as PoE, and provides network connectivity to end-user devices  116 - 126  (e.g., Voice over IP telephones, computers, etc.), one or more element management systems (EMSs)  112  and  114 , and a network management system (NMS)  110  via a network  104  and local area networks (LANs)  106  and  108 . LANs  106  and  108  may be connected to network  104  via links  134  and  136 , respectively; EMSs  112  and  114  may be connected to LANs  106  and  108  via links  130  and  132 , respectively; and NMS  110  may be connected to network  104  via link  128 . 
     PoN may be implemented by providing power insertion units such as PPPs in LANs  106  and  108 , for example. In a building installation, PPPs may be disposed in racks such as 19″ racks together with other LAN equipment such as switches, hubs, patch panels, etc. The racks may be placed in an equipment closet where an external network feed enters a building, and LAN switches may be connected to the network feed via a network switch, for example. 
       FIG. 2  shows an exemplary equipment closet  206  of a building floor plan  200  of building  202  for floor area  204 . In this example, LAN  106  serves floor  2  of building  202  and LAN  108  serves floor  3  which includes work areas  210 - 214 . LAN  108  may be connected to network  104  via a network switch  208  that may provide connections to network  104  for all LANs of building  202 . LAN  108  may be coupled to end-user devices  122 - 126  by horizontal cabling  216  via wall jacks  218 - 222  and may deliver power to end-user devices  122 - 126  through jacks  218 - 222 . 
     LANs may have many configurations such as an Ethernet star configuration, for example, that includes an Ethernet switch (switch) that permits communication between end-user devices and/or other networks. In the star configuration, end-user devices may be connected to the switch in a cross-connect configuration or an interconnect configuration.  FIG. 3A  shows a first conventional LAN cross-connect configuration that uses two conventional patch panels. As shown in  FIG. 3A , using LAN  106  as an example, all ports of a switch  230  are connected to a conventional patch panel  232  via cables connected from switch ports on switch  230  to punch-down blocks on the back side of conventional patch panel  232 . End-user devices  116 - 120  may be directly or indirectly connected to the patch panel  234  via horizontal cabling and punch-down blocks (not shown) on the rear face of patch panel  234 . Connections between patch panel  232  and patch panel  234  may be easily established and/or modified by changing patch cord connections between the front face ports of patch panel  232  and the front face ports of patch panel  234 . Such a cross-connect configuration optimizes the ease and flexibility with which connections between the horizontal cable plant may be established, rerouted, or removed. 
       FIG. 3B  shows a second conventional LAN cross-connect configuration that uses a power hub and a conventional patch panel. As shown in  FIG. 3B , using LAN  106  as an example, all ports of a switch  230  are connected to a conventional power hub  233  via cables connected from switch ports on switch  230  to a top row of ports on power hub  233 . End-user devices  116 - 120  may be directly or indirectly connected to a conventional patch panel  234  via horizontal cabling and punch-down blocks (not shown) on the rear face of patch panel  234 . Connections between power hub  233  and patch panel  234  may be easily established and/or modified by changing patch cord connections between the lower front face ports of power hub  233  and the front face ports of patch panel  234 . As addressed above with respect to  FIG. 3A , such a cross-connect configuration optimizes the ease and flexibility with which connections between the horizontal cable plant may be established, rerouted or removed. 
     By including power hub  233 , the cross-connect configuration depicted in  FIG. 3B  is able to insert PoN power over the respective horizontal cable network connections. However, because both the input ports and the output ports are on the front face of the power hub, the power hub requires twice the vertical space requirements in a standard equipment rack than a conventional patch panel. Therefore, the space requirements of a large network that uses power hubs in a cross-connect configuration are significantly greater than the space requirements of a patch panel-based cross-connect configuration. 
     The majority of deployed, large scale network infrastructure layouts were designed prior to the widespread acceptance of PoN. Therefore, the majority of deployed cross-connect configurations and the equipment rooms which accommodate those configurations were based upon equipment rack counts and internal equipment rack layouts based upon the use of a cross-connect configuration that uses standard equipment racks and single-height conventional patch panels, as shown in  FIG. 3A . 
     Theoretically, a network administrator should be able to introduce PoN service to a network by replacing a conventional patch panel (e.g., patch panel  232 ) as shown in the configuration shown in  FIG. 3A  with a power hub (e.g., power hub  233 ) to obtain the configuration shown in  FIG. 3B . However, the increased vertical height requirements of the power hubs typically prevent implementation of such a simple approach. Due to the increased vertical rack space requirements of a power hub, insertion of PoN within a deployed cross-connect-based network infrastructure using power hubs can result in significant added expenses by requiring:
         1. changes to internal rack configurations and cable configurations;   2. equipment racks to be added to equipment rooms;   3. expansion of equipment rooms to accommodate an increased number of equipment racks;   4. rearrangement of existing cabling and cable tray configurations to accommodate changes in equipment rack layouts.       

     The PPP supports insertion of PoN service without increasing, or otherwise adversely impacting, equipment rack space requirements as the PPP may have substantially the same dimensions as a conventional patch panel. Therefore, the PPP allows a new equipment room that uses PPPs for PoN insertion to be designed with a reduced number of equipment racks and reduced overall floor space requirements over a new equipment room design that uses power hubs for PoN insertion. Further, the PPP allows PoN service to be seamlessly inserted within any deployed network that uses conventional patch panels without affecting existing equipment rack or cable configurations, thereby greatly reducing the total cost of inserting PoN into an existing network, and allowing PoN service to be inserted within existing networks for which similar PoN insertion using power hubs would have been cost prohibitive. 
       FIG. 4A  shows an exemplary PPP-based LAN cross-connect configuration that supports PoN service. As shown in  FIG. 4A , using LAN  108  as an example, all ports of a switch  230  are connected to a conventional patch panel  232  via cables connected from switch ports on switch  230  to punch-down blocks on the back side of conventional patch panel  232 . End-user devices  122 - 126  may be directly or indirectly connected to a PPP  242  via horizontal cabling and punch-down blocks (not shown) on the rear face of PPP  242 . Connections between patch panel  232  and PPP  242  may be easily established and/or modified by changing patch cord connections between the front face ports of patch panel  232  and the front face ports of PPP  242 . Please note that the position of patch panel  232  and PPP  242  could be interchanged, without affecting the capabilities of the LAN cross-connect configuration shown in  FIG. 4A . Further, additional patch panels may be inserted between either of the configurations described above and the building horizontal cabling. 
       FIG. 4B  shows an exemplary PPP-based LAN interconnect configuration that supports PoN service. As shown in  FIG. 4B , using LAN  108  as an example, end-user devices  122 - 126  may be directly or indirectly connected to a PPP  242  via horizontal cabling and punch-down blocks (not shown) on the rear face of PPP  242 . Connections between switch  230  and PPP  242  may be easily established and/or modified by changing patch cord connections between the front face ports of switch  230  and the front face ports of PPP  242 . In an interconnect configuration, as shown in  FIG. 4B , technicians responsible for establishing and/or removing and/or changing connections between end-users (via the horizontal cabling plant) and the switch require access to switch  230 . Therefore, such a configuration is considered less secure than the equivalent cross-connect configurations shown in  FIGS. 4A and 4B . Such an interconnect configuration is typically installed in networks in which securing configuration and security control over switch  230  is not required. 
     As demonstrated above, the PPP is capable of inserting PoN service into a new or existing LAN by simply being substituted for and replacing a conventional patch panel. As such, the PPP is capable of supporting both cross-connect configurations (as shown in  FIG. 4A ) and interconnect configurations (as shown in  FIG. 4B ). 
     Building horizontal cable plants typically terminate at one or more equipment room patch panels that serve as horizontal cabling demarcation points. Such demarcation patch panels provide a clean physical termination of the horizontal cable plant cables. In addition, a patch panel-based demarcation point allows the respective network cables within the horizontal cable plant to be easily tested for TIA category 5e and 6 compliance and certified as compliant prior to hand-off of responsibility for the horizontal cable plant from, for example, a cable installer to, for example, the network engineers responsible for connecting equipment to the horizontal cable plant. Under current industry practices, the rear punch-down blocks of a patch panel are considered to be a sufficiently reliable and stable termination point for a horizontal network cable. However, under current industry standards, RJ-45 jacks on the front face of a hub are not considered a sufficiently reliable and stable termination point for a horizontal network cable. 
     Accordingly, although the PPP is capable of supporting both cross-connect configurations and interconnect configurations, a power hub is only capable of supporting a cross-connect configuration. Further, use of PPP  242  in a cross-connect configuration (e.g., by replacing patch panel  232  or patch panel  234  in  FIG. 3A ) allows PoE service to be introduced to an existing cross-connect configuration without adversely impacting equipment rack and existing cable plant/facility layouts. Use of PPP  242  in a cross-connect configuration (e.g., by replacing power hub  233  in  FIG. 3B ) allows PoE service to be maintained and results in a rack space savings for each power hub replaced with a PPP. Use of PPP  242  in an interconnect configuration (as shown in  FIG. 4B ) to replace an existing or planned cross-connect configuration results in an overall space savings of nearly 50% over an equivalent cross-connect configuration. This savings may be significant to rack space management when upgrading non-powered networks to PoE networks. Additionally, the interconnect configuration eliminates the need for patch cords between a power hub and a conventional patch panel, thereby reducing the number of cables required, reducing cable congestion within LAN equipment rooms, and reducing the likelihood of cable-related network connection faults. 
     The power hub, on the other hand, as addressed above, cannot be substituted within an existing cross-connect configuration without adversely affecting existing facility equipment rack space requirements and in some cases may adversely affect equipment room equipment rack counts, facility layouts, and cable plant layouts. Further, for reasons addressed above, a power hub is not capable of supporting an interconnect configuration and, therefore, does not allow facilities to capitalize upon the space savings that can be achieved by using an interconnect configuration in those facilities for which an interconnect configuration is acceptable. 
     In summary, regardless of whether an existing equipment room is configured in a cross-connect or interconnect configuration, PoE may be inserted using a PPP-based approach without impacting equipment room space requirements. The PPP approach may avoid significant infrastructure planning and/or infrastructure upgrades that may be associated with a power hub-based approach. 
     An exemplary NMS is described in U.S. patent application Ser. No. 11/209,817, filed on Aug. 24, 2005 and entitled “SYSTEMS AND METHODS FOR NETWORK MANAGEMENT,” which is hereby incorporated by reference in its entirety including all references cited therein. An EMS may be an NMS that is tailored to provide at least a subset of NMS features, but may include all the features of an NMS. The EMS may be configured to meet the needs of a specific set of intelligent network devices. 
     The NMS/EMS such as NMS  110  and EMSs  112 - 114  ( FIG. 1 ) may maintain a database of device information that may be retrieved from intelligent network devices (e.g., PPPs) through network system  100 . The NMS/EMS may further maintain within its database logical and physical topology information that describes the connectivity of devices within network system  100 . Physical topology information may include unique identifiers for each network device, physical locations of network devices such as building/floor/room number identifier, rack identification, position in the identified rack, horizontal cabling work area identification, and position relative to equipment racks, PPPs, PPP ports, PPP power sources, etc. Logical topology information may include network device connectivity such as PPP identification, PPP port number, jack identification, horizontal cable and work area jack identification, power source identification, etc. The database may also contain key cable performance measurements. 
     The PPP may serve as the primary repository of physical location information relative to the location of the PPP and the location of work areas supported by each of the ports within the PPP. For example, at the time of installation, a PPP may be configured with logical and physical location information (e.g., building, floor, room, GPS coordinates, IP address, IP mask, default IP gateway, etc.). The PPP may provide such information to the NMS/EMS, thus assuring that the logical and physical location information stored within the NMS/EMS is consistent with the actual network status. Further, at the time that each PPP port is wired via a punch-down block to an incoming cable, the location served by that cable may be entered into the PPP. For example, if the PPP is configured as a horizontal cabling demarcation patch panel, information such as the work area supported by the cable (e.g., building/floor/work area/wall jack, etc.) may be entered into the PPP and stored in a non-volatile memory. If the PPP is configured as a switch patch panel interface, information relating to the switch port supported by the cable (e.g., building/floor/equipment room/switched/port, etc.) may be entered and stored in the PPP. Such location information may be stored in a data structure specified by a definition interface file (DIF). In Simple Network Management Protocol (SNMP), a DIF corresponds to a Management Information Base (MIB). When the NMS/EMS requests information stored within a PPP&#39;s DIF data structure, the PPP may respond to the request by transmitting data stored within the data structure to the NMS/EMS, which may store the data within corresponding data structures in the NMS/EMS. For example, the NMS/EMS may have a DIF with data structures that include data structures that are identical to data structures defined by the PPP DIF so that information in a PPP&#39;s data structure may be retrieved and stored within a corresponding data structure within the NMS/EMS. 
     Further, the NMS/EMS may send PPP control parameters to control the PPP. The control parameters may be stored according to a DIF common to the PPP and the NMS/EMS so that efficient data transfer may be achieved. Each network device may have a unique DIF. Thus, the NMS/EMS stores all the unique DIFs within the network system  100  or within the subnet that it is configured to control and/or monitor. 
       FIGS. 5-8  show exemplary configurations of a PPP  400 .  FIG. 5  shows an exemplary PPP front panel  402  that may include a system status LED  410 , a plurality of ports  404 , a plurality of port status LEDs  406  where each LED  406  corresponds to one port  404 , a plurality of port labels  408 , which may be TIA-606-A compliant, and two rack mounting brackets  412  for mounting onto a rack, for example. 
       FIG. 6  shows a rear view of an exemplary PPP back panel  420  that may include two power input ports  422  and  424 , a network management input port  426 , a network management output port  428 , two status LEDs  430  and  432  that correspond to the network management input and output ports  426  and  428 , respectively, a plurality of punch-down blocks  434  that are grouped into eight groups of three punch-down blocks  434  per group, and a pair of plates  436  and  438  that extend from side panels of PPP  400 . Plates  436  and  438  protect punch-down blocks  434  from physical damage. For example, plates  436  and  438  allow PPP  400  to be rested rear face down on a flat surface without damaging punch-down blocks  434 . 
     As shown in  FIG. 7 , punch-down blocks  434  provide wire connections to PPP  400  for cables such as the horizontal cabling  216 . Damage to punch-down blocks  434  may render a PPP unusable. Thus, plates  436  and  438  reduce the risk of losing PPP  400  due to damage to punch-down block  434 . 
     Each of plates  436  and  438  may include a hole that may serve as a grounding point  440 . As shown in  FIG. 8 , PPP  400  may be securely grounded to a rack by connecting a ground strap  442  between the grounding point  440  and a point on the rack. 
       FIG. 9  shows an example of three PPPs  500   a ,  500   b , and  500   c  and a power supply  602  mounted onto a rack  600 . Power supply  602  may be a single power supply or may be a combination of multiple power supplies. For example, if power supply  602  includes two power supplies, then each of the power supplies may be independently connected to each of the PPPs  500   a - 500   c  in a redundant power supply configuration to provide fault tolerance. Power supply  602  may include power output ports  604   a ,  604   b , and  604   c , and, optionally, power output ports  606   a ,  606   b , and  606   c  if the redundant configuration is implemented. For example, power connections  608   a ,  608   b  and  608   c  may connect power output ports  604   a - 604   c  to power input ports  422  of PPPs  500   a - 500   c , and power connections  610   a ,  610   b , and  610   c  may connect power output ports  606   a - 606   c  to power input ports  424  of PPPs  500   a - 500   c  if the redundant power supply configuration is used. 
       FIG. 10  shows a diode “OR” circuit  441  that may be included in each PPP  500   a - 500   c  that combines power from two power supplies in a redundant power supply configuration. Power supply  602  may provide DC power having 48 volts, for example, and each of the power connections  608   a - 608   c  (or  942  of  FIG. 12) and 610   a - 610   c  (or  944  of  FIG. 12 ) may include two wires, one positive and one negative. A 48 volt DC power based approach avoids including an internal  110  AC-to-DC power supply, thereby precluding the need for an internal fan in a PPP, so that a PPP may replace, in a one-for-one manner, an existing conventional patch panel. Each of the power input ports  422  and  424  may include two connection points, one positive and one negative, so that the wires of the power connections  608   a - 608   c  and  610   a - 610   c  connect to corresponding ones of the connection points of the power input ports  422  and  424 , positive to positive and negative to negative. 
     Diode circuit  441  may include two diodes  442  and  444  or equivalent circuitry that models the functions of these diodes. Cathode terminals of diodes  442 - 444  may be electrically connected to negative connection points of respective power input ports  422  and  424  and anode terminals of diodes  442  and  444  may be electrically connected together at a node  446 . Positive connection points may be electrically connected to a node  448 . Nodes  446  and  448  provide power to the PPPs  500   a - 500   c . Diodes  442  and  444  prevent power from one of the power supplies from flowing into the other power supply. 
     Returning to  FIG. 9 , power supply  602  may include a network port  612  for connection to LAN  108 , for example, so that it may be controlled by NMS  110 , EMS  112  and/or EMS  114 . Network port  612  may be connected to an end of a daisy chain connecting all PPPs  500   a - 500   c  of rack  600 , for example.  FIG. 9  shows network management input port  426  of PPP  500   a  connected to a port of switch  230  of LAN  108  and network management output port  428  of PPP  500   a  connected to network management input port  426  of PPP  500   b . Network management output port  428  of PPP  500   b  may be connected to network management input port  426  of PPP  500   c , and so on if there are other PPPs on rack  600  until the last PPP of the daisy chain. Network management output port  428  of the last PPP may be connected to network port  612  of power supply  602 . In this way, all the PPPs  500   a - 500   c  and power supply  602  of rack  600  may connect to the LAN  108  using only one port of switch  230 , for example. 
       FIG. 11  shows a PPP internal Ethernet switch  450  that supports daisy chaining of network management input and output ports  426  and  428  and interface with internal PPP circuitry. The status of the network management input and output ports  426  and  428  may be indicated by status LEDs  430  and  432 , respectively (as shown in  FIG. 6 ). Table 1 below shows example indications of status LEDs and corresponding conditions associated with network management input and output ports  426  and  428 . 
     
       
         
               
             
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Network Status LED Indications 
               
             
          
           
               
                   
                 Network 
                   
                   
               
               
                 LED 
                 LED 
                   
                   
               
               
                 Color 
                 Status 
                 Description 
                 Notes 
               
               
                   
               
               
                 Off 
                 Off 
                 No connection to the  
                 If the system is otherwise 
               
               
                   
                   
                 NMS/EMS. 
                 operating normally and  
               
               
                   
                   
                   
                 an Ethernet cable is 
               
               
                   
                   
                   
                 connected, this could  
               
               
                   
                   
                   
                 be an issue 
               
               
                   
                   
                   
                 with the panel&#39;s  
               
               
                   
                   
                   
                 management interface. 
               
               
                 Green 
                 Flashing 
                 The management link  
                 Normal operation. 
               
               
                   
                   
                 on the PPP is 
                   
               
               
                   
                   
                 configured correctly  
                   
               
               
                   
                   
                 and communication  
                   
               
               
                   
                   
                 messages are 
                   
               
               
                   
                   
                 currently being  
                   
               
               
                   
                   
                 processed. 
                   
               
               
                 Green 
                 Solid 
                 The management link  
                 Normal operation. 
               
               
                   
                   
                 on the PPP is configured 
                   
               
               
                   
                   
                 correctly, but no 
                   
               
               
                   
                   
                 communication  
                   
               
               
                   
                   
                 messages are 
                   
               
               
                   
                   
                 currently being  
                   
               
               
                   
                   
                 processed 
                   
               
               
                   
                   
                 (i.e., the link is idle). 
                   
               
               
                 Amber 
                 Solid 
                 The PPP is currently  
                 If this persists for  
               
               
                   
                   
                 trying to  
                 more than a 
               
               
                   
                   
                 acquire DHCP  
                 minute or two, 
               
               
                   
                   
                 address information 
                 the daisy chain of 
               
               
                   
                   
                 from the network. 
                 connections between  
               
               
                   
                   
                   
                 multiple PPPs may be 
               
               
                   
                   
                   
                 incorrect or there are 
               
               
                   
                   
                   
                 problems at the DHCP 
               
               
                   
                   
                   
                 server. 
               
               
                   
               
             
          
         
       
     
       FIG. 12  shows a block diagram of circuitry in an exemplary PPP  900  that includes diode circuit  441 , an in-line current manager  910 , an analog-to-digital converter  948 , power-planes  904  and  908 , a common circuit  902  and a port circuit  906 . Assuming that two power supplies are used to provide fault tolerance, analog-to-digital converter  948  may monitor voltages of the two power supplies, nodes of diode circuit  441 , and output voltages generated by in-line current manager  910 , and provide digital values of the monitored voltages to processor  924  of common circuit  902  via optical coupler  918  (also called optical isolator). Processor  924  may also receive a value of current passing through in-line current manager  910 . These voltage and current values may be processed by processor  924  for processes such as:
         1. determining an input power consumption for the PPP;   2. calculating threshold values for low current and high current conditions based upon past and current use;   3. generating an event notification to NMS  110 , EMS  112  and/or EMS  114  containing voltage, current and calculated power measurements;   4. generating an event notification to NMS  110 , EMS  112  and/or EMS  114  when voltage values monitored in diode circuit  441  are below or above predetermined thresholds;   5. generating an event notification to NMS  110 , EMS  112  and/or EMS  114  when the current passing through in-line current manager  910  is below or above predetermined thresholds; and   6. generating event notification to NMS  110 , EMS  112  and/or EMS  114  when the power consumption of the PPP is below or above predetermined thresholds.       

     These and other event notifications may be logged by NMS  110 , EMS  112  and/or EMS  114  by storing data associated with the event notification, for example. An operator may view the logged event notifications on a per-port or per-PPP basis using a GUI for maintaining network system  100 . 
     As shown in  FIG. 12 , in-line current manager  910  separately outputs current-managed power to common circuit  902  and port circuit  906  via separately fused (by fuses  912  and  914 , respectively) power-planes  904  and  908 . Signal lines between in-line current manager  910 , common circuit  902  and port circuit  906  are isolated by optical couplers  918  and  922  and/or capacitive coupling  919 . In this manner, power failure in one of the power-planes  904  and  908  may be prevented from affecting power supplied to the other plane  904  or  908 . Thus, operation of the common circuit  902  may continue if power to power-plane  908  of port circuit  906  fails, or operation of port circuit  906  may continue if power to power-plane  904  of common circuit  902  fails. 
     For example, damage to port circuit  906  due to an accidental connection of a high voltage source to a cable connected to a PPP port could be prevented from affecting operations of common circuit  902 . Thus, common circuit  902  may continue to communicate with NMS  110 , EMS  112  and/or EMS  114  such as reporting status despite failure of port circuit  906 . Damage to common circuit  902  would be similarly prevented from affecting operations of port circuit  906 . Thus, PoE service may continue to be supplied to the PPP ports despite damage to common circuit  902 . 
     PPP embodiments may include any number of port circuits  906 . Each port circuit  906  may receive power from an isolated power plane  908  and each port circuit  906  may support a designated number of ports, as described herein. In this manner, an individual port circuit  906  may fail (e.g., due to a power surge or some other cause) and the remaining port circuits  906  may continue to operate normally. 
     Processor  924  may control system status LED  410  to indicate various PPP conditions as discussed above. Additionally, conditions such as listed below may be indicated by system status LED states:
         1. DHCP addressing (dynamic address);   2. power supply noise out-of-limit;   3. firmware update;   4. firmware compatibility;   5. loss of power for a power-plane which may indicate conditions such as a blown fuse;   6. input power not received;   7. processor initializing;   8. port circuit working properly; and   9. port circuit failed but common circuit working properly.       

     LED states such as single or multiple colors and toggling between colors, sequencing LED colors or blink rates, coded pulsing, and/or intensity variations may be used for indications of particular PPP conditions. Additionally, a blinking rate may be used instead of setting the LED to an on state to save power. Table 2 below shows other examples of possible system status LED states for different conditions of PPP  900 . 
     
       
         
               
             
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 PPP System Status LED Indications 
               
             
          
           
               
                 LED 
                 LED 
                   
                   
               
               
                 Color 
                 Status 
                 Description 
                 Status of Power Ports 
               
               
                   
               
               
                 Off 
                 Off 
                 No Power is being  
                 Power is NOT being  
               
               
                   
                   
                 supplied to the  
                 delivered to the  
               
               
                   
                   
                 PPP. 
                 ports on the PPP. 
               
               
                 Green 
                 Flashing 
                 System operating  
                 Power is being delivered  
               
               
                   
                   
                 normally. 
                 down the ports on 
               
               
                   
                   
                   
                 the PPP, as configured. 
               
               
                 Amber 
                 Solid 
                 Out of voltage range  
                 Power may or may not  
               
               
                   
                   
                 condition. Less 
                 be delivered to any 
               
               
                   
                   
                 than 46 VDC or  
                 ports on the PPP. 
               
               
                   
                   
                 more than 57 VDC 
                   
               
               
                   
                   
                 is being supplied to  
                   
               
               
                   
                   
                 the PPP. 
                   
               
               
                 Red 
                 Solid 
                 The main processor  
                 Power may or may not  
               
               
                   
                   
                 on the PPP is NOT  
                 be delivered to any 
               
               
                   
                   
                 operating properly  
                 ports on the PPP. 
               
               
                   
                   
                 and power is NOT  
                   
               
               
                   
                   
                 being delivered to any  
                   
               
               
                   
                   
                 ports on the PPP. 
               
               
                   
               
             
          
         
       
     
     As shown in  FIG. 12 , port circuit  906  may include a current manager  934 , a PoE manager  936 , an LED manager  938 , and a legacy detection support circuit  940  for each port of PPP  900 . Current manager  934  may include control logic such as a state machine that may control and monitor current flowing via each port to a connected end-user device. For example, current manager  934  may include current limiting circuitry that limits current flow based on values set in a register. 
       FIG. 13  shows an example of current manager  934  that includes a state machine  802 , a registers  804 , and a current limiter and switch  806 . Processor  924  may set control values in registers  804 . State machine  802  may control current limiter and switch  806  based on the values in registers  804 . For example, processor  924  may define thresholds in registers  804 . A first threshold may be an absolute current limit and a second threshold may set a current limit that may be exceeded for a first controlled period of time. When a port has exceeded the first threshold, state machine  802  may immediately command the current limiter and switch  806  to stop supplying current by opening a switch, for example. Additionally, the state machine  802  may update values in registers  804  (change state) and generate an alarm signal (an event) to processor  924  to indicate that the first threshold has been exceeded for the associated port. 
     When the second threshold is exceeded, state machine  802  may change state by updating registers  804  to set off a timer. If the current falls below the second threshold before the timer expires, then state machine  802  may return to its earlier state; otherwise, state machine  802  may enter a third state and switch off the port for a second control period of time before turning the port on again. State machine  802  may also set values in registers  804  to record a number of times the second threshold has been exceeded, for example, so that processor  924  may retrieve the values in registers  804  for reporting to NMS  110 , EMS  112 , and/or EMS  114 . 
     Processor  924  may monitor the current value measured by in-line current manager  910  over time (historical power use). Processor  924  may periodically use these measurements to calculate new current thresholds for use in monitoring current flow to PPP  900 . Current thresholds based on the historical power use may be better indictors of abnormal current use. 
     PoE manager  936  monitors each PPP port to detect the presence and characteristics of a PoE powered device (PD). As shown in  FIG. 14 , PoE manager  936  may include control logic such as a state machine  812 , registers  814 , and a PD interrogator  816 . Any number of state machines  812 , registers  814 , and PD interrogators  816  may be used, as may be dictated by implementation requirements, for example. If a PoE PD is detected, state machine  812  may change state by updating registers  814  and proceed to determine the PoE class of the PoE PD (classification). Once the class is determined, PoE manager  936  provides power to the PD based upon the PD&#39;s PoE class such as defined in IEEE 802.3af, for example. PoE manager  936  may also perform functions such as:
         1. determining which Ethernet cable pairs to distribute PoE power over;   2. controlling the types of PoE equipment to be detected (i.e., IEEE 802.3af equipment only, legacy equipment and/or other variations);   3. activating or deactivating PoE service on a per-port basis;   4. setting PD PoE priority and/or maximum power level, on a per-port basis;   5. controlling PoE priority on a per-port basis by setting a control parameter that controls port power priority to one of critical, high and low. In a low power event, PDs with higher power priorities should be disconnected only after power has been disconnected to ports with a lower power priority;   6. controlling PoE detection techniques on a per-port basis; and   7. controlling PoE PD power classification on a per-port basis. PD power classification indicates an amount of power the PD may be expected to consume.       

     State machine  812  may be controlled by control parameters stored by processor  924  in registers  814 . For example, processor  924  may force a port to stop supplying power by setting a “stop bit” in registers  814 . The “stop bit” may change the state of state machine  814  which may respond by opening a switch disconnecting power to the PD, for example. State machine  812  may report port status changes to processor  924  by sending one or more alert messages (events) to processor  924  or by updating registers  814  with new status information. Processor  924  may obtain the status information by reading the contents of registers  814 . 
     Status updates provided by PoE Manager  936  to processor  924  may indicate conditions such as:
         1. no PD is attached to the PPP port;   2. no power is being delivered over a PPP port;   3. power is being delivered over a PPP port; and   4. a PD has been detected but its power requirements cannot be determined.       

     Processor  924  may relay such status updates from PoE manager  936  via an event notification to NMS  110 , EMS  112 , and/or EMS  114 . In this manner, NMS  110 , EMS  112 , and/or EMS  114  may maintain accurate port-level connection and PoE-related information. 
     LED manager  938  controls port LEDs  406  and may include control logic such as a state machine  822 , a registers  824 , and an LED drive circuit  826 , as shown in  FIG. 15 . State machine  822  controls LED drive circuit  826  based on values in registers  824  which may be set by processor  924 . For example, processor  924  may force LED  406  of a specific port to blink at a specified rate by setting values in registers  824  in response to move/add/change requests received from NMS  110 , EMS  112 , and/or EMS  114 . Other LED states such as single or multiple colors, toggling between colors, sequencing LED colors or blink rates, coded pulsing, and/or intensity variations may be used for indications of particular port conditions. State machine  822  may control LED drive circuit  826  based on the values in registers  824  set by processor  924 . 
     State machine  822  may change values in registers  824  based on current LED functions being performed reflecting the status of the associated port so that processor  924  may read the status when performing monitoring functions. Port conditions such as the following may be indicated using LEDs  406 :
         1. power level indicator for power classification of connected PD;   2. power removed from the port (lockdown), over-current for all ports per classification;   3. over-current conditions for a particular port (administrative restriction);   4. backing off supplying power because connected device is a powered switch;   5. PD voltage incompatibility;   6. port power interface failure;   7. power classification fault; and   8. port power noise outside of limits.
 
Additionally, LEDs  406  may be used to assist an operator for patch cord tracing and/or direct patch cord removal/change.
       

     Other LED functions may be similarly set by processor  924 , such as color, for example. Additionally, state machine  822  may control the LED  406  via LED drive circuit  826  to perform a specific function based on conditions of the associated port. Examples of this type of control are shown in Table 3, below. 
     
       
         
               
             
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 Port Status LED Indications 
               
             
          
           
               
                   
                 Port 
                   
                   
               
               
                 LED 
                 LED 
                   
                   
               
               
                 Color 
                 Status 
                 Description 
                 Status of Power Ports 
               
               
                   
               
               
                 Off 
                 Off 
                 No Powered Device (PD)  
                 Power is NOT being 
               
               
                   
                   
                 is wired to this particular  
                 delivered down this  
               
               
                   
                   
                 port on the PPP. 
                 port on the PPP. 
               
               
                 Amber 
                 Solid 
                 The PPP is determining the  
                 Power is NOT being 
               
               
                   
                   
                 PD&#39;s power requirements. 
                 delivered down this  
               
               
                   
                   
                 This occurs for 5 seconds  
                 port on the PPP. 
               
               
                   
                   
                 after the PD is connected. 
                   
               
               
                 Green 
                 Solid 
                 Port operating normally. 
                 Power is being  
               
               
                   
                   
                   
                 delivered down this 
               
               
                   
                   
                   
                 port on the PPP. 
               
               
                 Red 
                 Solid 
                 The system has failed to  
                 Power is NOT being 
               
               
                   
                   
                 determine the PD power 
                 delivered down this  
               
               
                   
                   
                 requirements for this port.  
                 port on the PPP. 
               
               
                   
                   
                 Perhaps this PD is not  
                   
               
               
                   
                   
                 an 802.3af compliant or  
                   
               
               
                   
                   
                 legacy device (e.g.,  
                   
               
               
                   
                   
                 Cisco). It could also be a  
                   
               
               
                   
                   
                 port configured for  
                   
               
               
                   
                   
                 802.3af and an alternate  
                   
               
               
                   
                   
                 PoE device has  
                   
               
               
                   
                   
                 been connected. 
               
               
                   
               
             
          
         
       
     
     Legacy detection support circuit  940  together with PoE manager  936  and processor  924  executes an exemplary process  1500  shown in  FIG. 16  that determines whether an end-user PD connected to a port is a first type of PoE device such as an IEEE 802.3af compatible device or a second type of PoE device such as a legacy device. 
     In step  1502 , the process determines whether a port is connected to a first type PD. For example, if a first type PD is an IEEE 802.3af PoE device, then it may be detected by procedures specified in the IEEE 802.3af standards. If a first type PD is detected, then the process goes to step  1504 ; otherwise, the detection process, at step  1502 , may be repeated after a predetermined delay. In step  1504 , the process may classify the PoE PD (determining power requirements by interrogating the PoE device) and the process goes to step  1510 . In step  1510 , the process may provide power to the PoE PD according to the determined classification, may set the LED associated with the port to a state as specified by contents of registers  824 , and may optionally update a state field in registers  824 . Next, the process goes to step  1512 . 
     In step  1512 , the process determines whether there is a change in the status of the port, e.g., whether the connected PD has been disconnected. If there is a change, the process returns to step  1502 ; otherwise, the process goes to step  1514 . In step  1514 , the process determines whether the PPP is turned off. If the PPP is turned off, the process goes to step  1516  and ends; otherwise the process returns to step  1512 . 
     While process  1500  is executing, another process  1550 , as shown in  FIG. 17 , may be executing based on a timer to determine whether a first type device is connected. If a first type of device is not connected, the process executes a second type detection process. In step  1552 , the process determines whether the timer has expired. If expired, the process goes to step  1554 ; otherwise, the process returns to step  1552 . In step  1554 , the process determines whether the port is supplying power to a first type or a second type PoE PD. If the port is supplying power, the process goes to step  1556 ; otherwise the process goes to step  1558 . In step  1556 , the timer is set and the process returns to step  1552 . 
     In step  1558 , the process determines whether the port is connected to a second type device such as a legacy device (legacy relative to IEEE 802.3af PoE PDs). An example of how such a determination may be made is shown in  FIG. 18A , which shows an exemplary PPP legacy detection support circuit  940  connected via a 4-pair twisted-pair cable to an exemplary legacy PD configured to receive PoN power over wire-pairs 4/5 and 7/8. Legacy detection support circuit  940  may include an oscillating signal generator  1202  that transmits an oscillating signal on wire-pair wires 4, 5 via transmission driver  1204  and transformer  1206 . 
     A legacy PD may be configured such that when a cable is inserted into the PD, physical switch  1210  is moved from an open to a closed position. Therefore, if the PD is a legacy device, the oscillating signal emitted by oscillating signal generator  1202  on wire-pair wires  4 ,  5  will be transmitted via transformer  1208  and  1212  to wire-pair 7/8, and detected by detection circuit  1218 , via receiver  1216  and transformer  1214 . If the PD is not a legacy device, physical switch  1210  remains in the open position and detection circuit  1218  does not receive a corresponding signal in response to the oscillating signal output. If no signal is received detection circuit  1218  determines that the PD is not a legacy device. 
     If detection circuit  1218  determines that the connected PD is a legacy device, detection circuit  1218  communicates (via connection lines not shown in  FIG. 18A ) with polarity reverse switch  1220  to place a negative voltage across leads  1222  and  1224 , as shown in  FIG. 18B . If detection circuit  1218  determines that the connected PD is not a legacy device, detection circuit  1218  communicates with polarity reverse switch  1220  to place a positive voltage across leads  1222  and  1224 . In this manner, an appropriate voltage is placed upon leads  1222  and  1224  and power is transmitted via wiretaps in transformers  1206  and  1214  and via wire-pairs 4/5 and 7/8, respectively, to wire taps on transformers  1208  and  1212  in the PD device. Power received by the PD device at wire taps on transformers  1208  and  1212  is delivered via PD circuit  1226  with diode circuit  1228  to drive PD load  1230 . 
     Returning to  FIG. 17 , if a second type PoE PD is detected, the process goes to step  1560 ; otherwise, the process goes to step  1556 . In step  1560 , the process determines the power requirements of the second type device, provides the required power, and goes to step  1562 . In step  1562 , the process determines whether the PPP has been turned off. If turned off, the process goes to step  1564  and ends; otherwise, the process goes to step  1556 . 
     The managers within port circuit  906  (i.e., current manager  934 , PoE manager  936 , and LED manager  938 ) may operate as independent state machines that interact with processor  924  to receive control parameter updates from processor  924  and to provide status updates to processor  924 . As noted above, the port circuit  906  may operate independently of processor  924 . For example, in the event that the PPP is powered down, reset or in self-test, either intentionally (e.g., to field-update newly downloaded processor code) or unintentionally (due to a power failure or internal fault-generated reset) port circuit processing may be unaffected and port circuit  906  may continue to support PoE-based services to the PPP ports based on the latest parameters received from processor  924 . Once processor  924  is again operational, normal communications between processor  924  and the port circuit  906  may resume. 
     Returning to  FIG. 12 , common circuit  902  may include processor  924 , a memory  926  which may include random access memory (RAM)  928  and non-volatile memory  930 , and a two-port Ethernet switch  932 . If PPP control parameters and configuration data such as location and connection information and associated DIFs are stored in non-volatile memory  930 , PPP  900  may return to the stored PPP configuration if power was accidentally lost causing PPP  900  to restart, for example. Control and configuration parameters that may be stored in non-volatile memory  930  may include:
         1. PPP configuration parameters;   2. PPP and PoE-related current and voltage thresholds;   3. PPP network IP configuration data;   4. event notification (e.g., SNMP trap) recipients; and   5. PPP identity, PPP physical location information and associated power supply identification and location information.       

     Processor  924  may control operations of PPP  900  based on control parameters and data stored in memory  926 , and may communicate with other devices via Ethernet switch  932 . Memory  926  may be used to store software that may be executed by processor  924 . Processor  924  may control port circuit  906  to perform its functions by setting the registers  804 ,  814 , and  824  based on received control parameters. Additionally, processor  924  may perform the following functions:
         1. controlling a port based on whether the PoE PD may receive AC/DC PoE detection or DC only detection;   2. controlling whether control/administration of port-level values by an NMS/EMS may be accepted by the PPP; and   3. controlling whether wire assignments for transmitting power may be changed.       

     NMS  110 , EMS  112 , and EMS  114  may interface with a GUI that permits an operator to maintain and control the network and administer desired policies. For example, such a GUI may permit the operator to graphically view monitored power and one or more failure statuses of devices such as PPPs and devices connected to the PPPs. 
     The GUI may provide a graphical display of the topology of network system  100  which may be organized into trees, and each branch of the tree may form a sub-network (subnet) of network system  100 . The GUI may display a subnet in relation to actual physical locations such as, for example, a floor plan detailing physical aspects of the building where PPPs may be disposed, such as equipment closet  206  and racks  600 . The GUI may provide displays such as:
         1. a hierarchical view of all PPPs;   2. a listing of PPPs;   3. information for each PPP of a selected rack including logged event notifications; and   4. detailed configuration, control and status information for a specifically selected PPP, including:
           a. a message log of event notifications generated by the PPP;   b. current and historical power usage values for each PPP; and   c. physical location and logical connection information.
 
The GUI may provide capabilities to support functions such as searching for panels of a selected subnet across a range of IP addresses, viewing and/or changing information on a per-port basis of each PPP, etc.
   
               

     The network topology may be derived from PPPs by either explicitly requesting needed information or receiving unsolicited notifications from PPPs resulting from local monitoring functions. For example, data that may be received from PPPs may include:
         1. physical location information such as room identification, rack identification, horizontal cabling work room identification;   2. connection information such as PPP and port identification, switch port identification, power supply source identification;   3. whether or not powered devices are connected to a port;   4. an amount of current consumption. This is especially relevant to intelligent network devices such as a PPP because PPPs supply power to their ports and the total amount of power supplied through a PPP may be monitored for network power budget purposes;   5. information (e.g., a PD identifier and/or a PPP port identifier) related to an abnormal termination of power to a powered PD and which, based upon the PPP&#39;s PD interrogation techniques, appears to have been disconnected;   6. non-compliant PDs such as PDs whose power consumption is over specified limits;   7. PPP power consumption has dropped below a threshold;   8. PPP power consumption has exceeded a threshold;   9. PPP physical location has been changed;   10. PPP incoming voltage is outside desired range (e.g., too high or too low);   11. PPP power fuse has blown;   12. the amount of incoming power to a PPP;   13. PPP-detected management port connections; and   14. PPP-detected management port disconnections.       

     An operator may use the GUI to control network system  100  by setting various parameters of PPPs. For example, an operator may:
         1. perform maintenance by monitoring any PPPs (e.g., verify port connections by sending test signals, confirm connection to a PPP, etc.);   2. designate priority for output power for any port of a PPP. For example, a port may be designated as low, high or critical priority;   3. set thresholds for power consumption for a PPP or any of its ports. For example, such thresholds may be set in the form of current and/or voltage values;   4. perform real-time monitoring and setting thresholds of current and voltage of power inputs for a PPP, for example. Thresholds may be set for detection of alarm conditions;   5. monitor a parameter, such as a voltage or current, of a first power supply, a parameter of a second power supply and a parameter at a summation point when a PPP is supplied by two power supplies, for example;   6. command outputting full power for all ports of a PPP;   7. detect and display power consumption for a PPP or one or more ports of the PPP;   8. assign dynamic (DHCP) or static IP address to a PPP at installation, for example;   9. selectively deactivate/re-activate power service to a PPP port;   10. control operation of LEDs of a PPP (e.g., blinking rate, on/off, etc.); and   11. assign power mode (e.g., normal, forced or forced with device check) for each port of a PPP. For example, in ‘normal’ power mode, the PPP may manage the application of PoE power to a port based upon whether a device is connected to a port and/or the type of device connected to the port and/or power consumption monitoring; in ‘forced with device check’ power mode, the PPP may apply PoE power to a port when a device is connected to the port, regardless of the type of device connected and/or without power consumption monitoring; and in ‘forced’ power mode, the PPP may apply PoE power to a port without checking for a device or any power consumption monitoring.       

     It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. For example, “a” may denote the use of one or more elements. The lists presented herein are intended to be exemplary rather than limiting. Also, variations presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art, and are also intended to be encompassed by the following claims.

Technology Category: 5