JP2018157384A - Network system, LAN switch and PoE power supply method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a network system capable of supplying power from a high-order network apparatus to a PoE end device by means of PoE even in a case where a power source is lost in a LAN switch including a PoE pass-through function.SOLUTION: A LAN switch 10 including a PoE pass-through function comprises a returning part 1111 for automatically determining whether to form a return path connecting an up port 118 for PoE for connecting a high-order LAN switch 20 including a power supply function by PoE and a down port 117 for PoE for connecting a PoE end device 30 including a power receiving function by PoE in a returning manner in accordance with the presence/absence of power supply from a power source circuit 115 inside of a first physical layer processing part 111 including a function for applying processing of a physical layer relating to a signal to be transmitted/received in each of the up port 118 for PoE and the down port 117 for PoE, and a function for performing relay transmission of power by PoE.SELECTED DRAWING: Figure 1A

Description

  The present invention relates to a network system, a LAN (Local Area Network) switch, and a PoE power supply method, and more particularly to a network system, a LAN switch, and a PoE power supply method that supply power by PoE (Power Over Ethernet).

  FIG. 5 is a schematic diagram for explaining a PoE pass-through compatible LAN switch. Here, PoE is a technology that makes it possible to supply power via a LAN cable so that it is possible to deal with cases where it is difficult to secure a wiring space for a power supply when constructing a LAN network. is there. PoE enables both signal transmission and power supply for communication for network devices with a single LAN cable. The PoE pass-through is a power relay function that the LAN switch 10 has. In the example of the network configuration in FIG. 5, the power relay function of the LAN switch 10 uses the power supplied by the PoE from the host LAN switch 20 that is the host network device (that is, the power supplied by PoE) via the LAN switch 10. Thus, the PoE end device 30 can be supplied by PoE. In FIG. 5, PoE power feeding paths 12 and 13 and a PoE pass-through power feeding path 11 are configured as power feeding paths.

  Referring to the PoE pass-through compatible LAN switch 10 in FIG. 5, the PoE power supply path 12 operates the LAN switch 10 itself with power supplied from the upper network device, for example, the upper LAN switch 20 by PoE, and the PoE power supply path 13 is The remaining power is supplied from the LAN switch 10 to the PoE end device 30 by PoE, and the PoE pass-through power supply path 11 operates the LAN switch 10 itself by the power supplied from the power source built in the LAN switch 10. The power supplied from the network device, for example, the upper LAN switch 20 through PoE is supplied as it is from the LAN switch 10 to the PoE end device 30 through PoE.

  In the case of the PoE pass-through power supply path 11 type, when the power supply built into the LAN switch 10 is lost, the PoE end device 30 connected to the PoE supply port of the LAN switch 10 cannot be operated. Therefore, in the technology disclosed in Japanese Patent No. 5355534 “Network Concentrator and Power Control Method” of Patent Document 1, the power saving of the PoE pass-through-compatible LAN switch 10 can be achieved by It is possible to continue operation by supplying power from an auxiliary power source such as a battery, or when the auxiliary power source is also unable to supply power, it is supplied by PoE from an upper network device, for example, the upper LAN switch 20 Even with only electric power, it is possible to operate over a long period of time.

  However, no matter how the power saving of the PoE pass-through compatible LAN switch 10 is achieved, the auxiliary power source has a limitation on the operation period during which power can be supplied. Further, even when the operation is performed with the power supplied from the host LAN device 20 such as the PoE from the host LAN switch 20, the power consumption of the operation of the LAN switch 10 and the PoE end device 30 as the power supply destination is the upper network device such as If the power supplied from the host LAN switch 20 by PoE is exceeded, the PoE end device 30 cannot be operated. Therefore, in the current technology related to the present invention such as the above-mentioned Patent Document 1, the problem that the PoE end device 30 cannot be operated when the internal power supply in the LAN switch 10 is lost is ensured. The problem that cannot be solved remains.

Japanese Patent No. 5355534

  As described above, in the current technology related to the present invention such as Patent Document 1 described above, when the PoE pass-through compatible LAN switch loses the main power supply and the auxiliary power supply and the power supply is cut off, the lower PoE There is a problem to be solved that there is a possibility that power for operating the end device cannot be supplied.

(Object of the present invention)
The present invention has been made in view of such a problem to be solved, and in a LAN switch having a PoE pass-through function, even if the main power supply or the auxiliary power supply is lost, the lower PoE end device operates. It is an object of the present invention to provide a network system, a LAN switch, and a PoE power supply method that can supply power necessary for the transmission from a higher-level network device such as a higher-level LAN switch by PoE.

  In order to solve the above-described problems, the network system, the LAN switch, and the PoE power supply method according to the present invention mainly adopt the following characteristic configuration.

(1) A network system according to the present invention includes:
Receiving the power supplied by the communication function and the PoE, the host network device having the communication function and the power supply function by PoE, the LAN switch having the communication function and the PoE pass-through function for relaying the power by PoE A PoE end device having a function, comprising:
The LAN switch having a PoE pass-through function is:
A PoE up port for connecting to the host network device;
A PoE down port for connection to the PoE end device;
A function of performing physical layer processing on signals transmitted and received at the PoE up port and the PoE down port by connecting to the PoE up port and the PoE down port, and relaying of power received by the PoE A first physical layer processing unit having a function of performing transmission;
The first physical layer is selected between one port or a plurality of ports including the PoE down port on the lower side and between the selected port and the PoE up port on the upper side. A switch unit connected via a processing unit;
A power supply circuit connected to a power supply, and supplying power supplied from the power supply to each part to be fed,
The first physical layer processing unit determines whether or not to connect the PoE up port and the PoE down port so as to be folded back at a physical layer stage depending on whether power is supplied from the power supply circuit. It further has a folding portion that is automatically set.

(2) The LAN switch according to the present invention is:
Power relay by PoE interposed between a host network device having a communication function and a function of supplying power by PoE, and a PoE end device having a communication function and a function of receiving power supplied by PoE A LAN switch having a PoE pass-through function and a communication function,
A PoE up port for connecting to the host network device;
A PoE down port for connection to the PoE end device;
A function of performing physical layer processing on signals transmitted and received at the PoE up port and the PoE down port by connecting to the PoE up port and the PoE down port, and relaying of power received by the PoE A physical layer processing unit having a function of performing transmission;
The physical layer processing unit selects any one of a plurality of ports including the PoE down port on the lower side and connects the selected port and the PoE up port on the upper side. A switch unit connected via
A power supply circuit connected to a power supply, and supplying power supplied from the power supply to each part to be fed,
The physical layer processing unit automatically determines whether or not to connect the PoE up port and the PoE down port so as to be turned back at the physical layer stage, depending on whether or not power is supplied from the power supply circuit. It further has a turn-back portion set to the above.

(3) The LAN switch power feeding method according to the present invention includes:
Receiving the power supplied by the communication function and the PoE, the host network device having the communication function and the power supply function by PoE, the LAN switch having the communication function and the PoE pass-through function for relaying the power by PoE A PoE power feeding method in a network system having a PoE end device having a function,
The LAN switch having a PoE pass-through function is:
A function for performing physical layer processing on signals transmitted and received in each of the PoE up port for connecting to the upper network device and the PoE down port for connecting to the PoE end device, and receiving power by PoE A physical layer processing step having a function of performing relay transmission of the generated power;
The physical layer processing step of selecting any one of one or more ports including the PoE down port on the lower side and connecting the selected port and the PoE up port on the upper side A switch step to be connected after the processing in
A return path that connects the PoE up port and the PoE down port so as to return at the physical layer stage depending on whether or not power is supplied from a power supply circuit for supplying power to each part to be fed. And a folding step for automatically determining whether or not to form.

  According to the network system, the LAN switch, and the PoE power supply method of the present invention, when a power supply interruption occurs in the LAN switch having the PoE pass-through function, the lower PoE down port and the upper PoE up port There is provided a turn-back portion that connects the two at a physical layer stage. Thus, according to the present invention, even when the power supply of the switch having the PoE pass-through function is cut off, the power supplied by the PoE from the upper network device, for example, the upper LAN switch, is transmitted to the PoE end device. The effect that it becomes possible to supply reliably by this can be show | played.

It is a figure which shows the structure of the network system which concerns on embodiment of this invention. It is a figure which shows an example of the 1st physical layer process part which is one of the internal structures of the network system of FIG. 1A, and its input / output structure. It is a schematic diagram which shows the connection state of the folding | turning part when the electric power supply from the electric power supply line of a power supply circuit is interrupted | blocked. It is a schematic diagram for demonstrating an example of the internal structure of a folding | returning part. It is a schematic diagram for explaining a return path when a switch in the return part is set to an on (connected) state. It is a schematic diagram for demonstrating the LAN switch corresponding to PoE pass-through.

  Preferred embodiments of a network system, a LAN switch, and a PoE power supply method according to the present invention will be described below with reference to the accompanying drawings. It should be noted that the reference numerals attached to the following drawings are added for convenience to each element as an example for facilitating understanding, and it is needless to say that the present invention is not intended to be limited to the illustrated embodiment. Yes.

(Features of the present invention)
Prior to the description of the embodiments of the present invention, an outline of the features of the present invention will be described first. The present invention enables a LAN switch having a PoE pass-through function to reliably supply power supplied by PoE from a higher-level network device, for example, a higher-level LAN switch, to a PoE end device even when its own power supply is lost. Is the main feature.

  More specifically, a LAN switch having a PoE pass-through function can reliably supply power supplied by PoE from an upper network device, for example, an upper LAN switch, to a PoE end device even when power is lost. Therefore, the main feature is that it has a configuration in which a circuit (folding unit) for connecting / disconnecting a PoE down port, that is, a PoE power supply port, and a PoE up port, that is, a PoE power receiving port, is added to the physical layer stage. Yes. Thus, when the power of the LAN switch itself having the PoE pass-through function is lost, the LAN switch PoE down port and PoE up port are automatically connected directly at the physical layer stage. Thus, the power supplied by the PoE from the host network device, for example, the host LAN switch is supplied as it is to the PoE end device connected to the PoE down port, that is, the PoE power receiving port. It is possible to drive.

(Configuration example of embodiment of the present invention)
Next, a configuration example of the LAN switch according to the embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1A illustrates a network configuration of a network system according to an embodiment of the present invention, and FIG. 1B is a configuration diagram illustrating an example of an internal configuration of a LAN switch that configures the network system. Here, FIG. 1B shows the internal configuration of the LAN switch. The internal configuration shown here is an example of the internal configuration of the LAN switch having a function compatible with PoE pass-through. A network system 1 shown in FIG. 1A has a network configuration including network devices such as a host LAN switch 20, a LAN switch 10, and a PoE end device 30.

  The upper LAN switch 20 is an upper network device located on the upper side of the LAN switch 10, and in addition to the communication function, a LAN cable for communication is provided to the LAN switch 10 which is a lower side network device by PoE. It is a network device that can supply power through the network. Although the internal configuration will be described later, the LAN switch 10 is a network device provided with a PoE pass-through function for performing relay transmission of power received by PoE in addition to a communication function. That is, the LAN switch 10 uses the PoE end device 30 which is a lower level network device to communicate power supplied by PoE from an upper level network device, for example, the higher level LAN switch 20 (that is, power supplied by PoE). A function of supplying via a LAN cable is provided. The PoE end device 30 is a network terminal device located on the lower side. In addition to the communication function, the PoE end device 30 is supplied with power (that is, PoE power is supplied from the upper side network device via the communication LAN cable by PoE. It is a device having a function of receiving power. The PoE end device 30 is a network terminal device such as a notebook PC (Personal Computer) having a power receiving function via a LAN cable, for example.

  Inside the LAN switch 10, as shown in FIG. 1A, the first physical layer processing unit 111, the second physical layer processing unit 112, the switch unit 113, the control unit 114, the power supply circuit 115, the power supply 116, and the PoE A down port 117, a PoE up port 118, and a port group 119 are provided at least. The first physical layer processing unit 111 includes at least a folding unit 1111, a download buffer 1112, and an upload buffer 1113 as shown in FIG. 1B.

  The PoE down port 117 is a port that is capable of PoE power supply and accommodates a LAN cable that connects the PoE end device 30 shown in FIG. 1A. The PoE up port 118 is a port that is capable of receiving PoE power, and is a port that accommodates a LAN cable connecting the host network device, for example, the host LAN switch 20 shown in FIG. 1A. Each port further has a function of performing communication and transmitting PoE power. The first physical layer processing unit 111 connects the PoE down port 117 and the PoE up port 118 via the down line 1171 and the up line 1181, respectively, and connects the PoE down port 117 and the PoE up port 118 respectively. A function for performing physical layer processing (that is, processing such as waveform shaping, amplification, and code conversion) on a signal transmitted / received via the network, and a function for performing relay transmission of power received by PoE (that is, PoE upport) A function of supplying power received from the upper network device via 118 to the lower network device via the PoE down port 117).

  In addition, the folding unit 1111 provided in the first physical layer processing unit 111 includes a switch inside as illustrated in FIGS. 3 and 4 to be described later, and PoE depending on the power supply state of the power supply circuit 115. Either the down line 1171 connected to the down port 117 for connection and the up line 1181 connected to the up port 118 for PoE are connected so as to be turned back at the physical layer stage or not connected to be opened. Set to either state. The download buffer 1112 is connected to the up line 1181 connected to the PoE up port 118 via the loopback unit 1111, and temporarily stores data downloaded from the upper network device, for example, the upper LAN switch 20. It is. On the other hand, the upload buffer 1113 is connected to a down line 1171 connected to the PoE down port 117 via a loopback unit 1111 and temporarily stores data uploaded from the PoE end device 30.

  The port group 119 includes one or a plurality of ports for accommodating one or a plurality of cables respectively connecting one or a plurality of network terminal devices connected to the lower side, and the second physical layer process. The unit 112 is connected to a port group 119 including one or a plurality of ports, and processes physical layers (that is, processes such as waveform shaping, amplification, and code conversion) for signals transmitted / received via each of the plurality of ports. It has a function to apply.

  The switch unit 113 is connected to the PoE down port 117, the PoE up port 118, and the port group 119 via the first physical layer processing unit 111 and the second physical layer processing unit 112. Based on the instruction, the PoE down port 117 in the downlink direction on the lower side and the port group 119 are selected, and the PoE up in the uplink direction on the selected port and the upper side is selected. The switch is connected to the port 118 via the first physical layer processing unit 111. That is, a signal is transmitted and received between the lower port connected to the switch unit 113 and the upper PoE up port 118. The switch unit 113, in accordance with an instruction from the control unit 114, includes a download buffer 1112 and an upload buffer 1113 provided in the first physical layer processing unit 111, and a corresponding downlink port, PoE. It is also possible to switch so as to connect with the up port 118.

  In addition, the control unit 114 controls the operation of each part of the LAN switch 10 to control the operation of the entire LAN switch 10. In addition, the power supply circuit 115 is connected to the power supply 116 and supplies the power supplied from the power supply 116 to each part of the LAN switch 10 to which power is supplied.

  The power supply line 1151 from the power supply circuit 115 is also connected to the folding unit 1111 provided in the first physical layer processing unit 111, and power is supplied from the power supply line 1151 to the folding unit 1111. In the case where it has been done, the switch in the folding section 1111 is set to the open state. Therefore, the down line 1171 connected to the PoE down port 117 and the up line 1181 connected to the PoE up port 118 are not directly connected but are opened to each other. As a result, in such a state, each of the down line 1171 connected to the PoE down port 117 and the up line 1181 connected to the PoE up port 118 is connected to the switch unit 113 and is controlled by the control unit 114. Determines whether or not they are connected to each other.

  On the other hand, when the power supply from the power supply line 1151 to the folding unit 1111 is interrupted, the switch in the folding unit 1111 is set to a closed state. Accordingly, the down line 1171 connected to the PoE down port 117 and the up line 1181 connected to the PoE up port 118 are directly connected so as to return at the physical layer stage, and the return path via the return unit 1111. Is formed. FIG. 2 is a schematic diagram illustrating a connection state of the folded portion 1111 when the power supply from the power supply line 1151 of the power supply circuit 115 is interrupted. As shown in FIG. 2, when the power supply from the power supply line 1151 is interrupted, the space between the down line 1171 connected to the PoE down port 117 and the up line 1181 connected to the PoE up port 118 is A folding path 200 that is directly connected to each other via the folding section 1111 is automatically formed.

  FIG. 3 is a schematic diagram for explaining an example of the internal configuration of the folded portion 1111. Note that FIG. 3 shows a case where the switch 11111 provided in the folded portion 1111 is set to an off (open) state. As shown in FIG. 3, each of a down line 1171 consisting of eight signal lines connected to the PoE down port 117 and an up line 1181 consisting of eight signal lines connected to the PoE up port 118 are shown. The signal lines are connected via eight switches 11111 provided in the folded portion 1111.

  The eight switches 11111 are set to an off (open) state as shown in FIG. 3 in a state where power is supplied from the power supply line 1151 of the power supply circuit 115. As a result, the down line 1171 connected to the PoE down port 117 and the up line 1181 connected to the PoE up port 118 both pass through the loopback part 1111 in the first physical layer processing part 111. Then, it is connected to the upper layer switch unit 113, and forms a down direction path 201 and an up direction path 202, respectively, as indicated by thick double arrows in FIG.

  On the other hand, when the power supply is cut off, the eight switches 11111 are forcibly set to the on (connected) state as shown in FIG. As a result, the down line 1171 connected to the PoE down port 117 and the up line 1181 connected to the PoE up port 118 are turned back at the turn-back unit 1111 in the first physical layer processing unit 111 at the physical layer stage. The signal and PoE power transmitted / received and connected to are transmitted / received via the return path 200 as indicated by the thick double-headed arrow in FIG. 4 without going to the upper layer switch unit 113. FIG. 4 is a schematic diagram for explaining the return path 200 when the switch 11111 in the return part 1111 is set to the on (connected) state. In FIG. 4, only one signal line is representatively shown with a thick double arrow, but actually, the switch 11111 is turned on (connected) in all eight signal lines. In addition, the return path 200 is formed in all the signal lines.

  In the LAN switch 10 shown in FIG. 1A, a port group 119 composed of one or a plurality of ports for accommodating one or a plurality of cables connecting the network devices connected to the lower side, and a port The case where the second physical layer processing unit 112 that performs processing such as waveform shaping, amplification, code conversion, and the like is illustrated with respect to a signal transmitted and received through each of a plurality of ports connected to the group 119 is illustrated. When the network terminal device connected to the lower side includes only a device capable of receiving PoE power, that is, the PoE end device 30, it is not necessary to include the port group 119 and the second physical layer processing unit 112. . In such a case, it is needless to say that the first physical layer processing unit 111 can be handled as a simple “physical layer processing unit” without “first”.

  The power supply 116 connected to the power supply circuit 115 is a power supply external to the LAN switch 10, but may be a power supply built in the LAN switch 10, and the power supply 116 is mainly used. Of course, the power supply may have a configuration in which an auxiliary power supply is provided in the inside as a countermeasure against a failure of the main power supply or a power failure.

(Description of the operation of the embodiment of the present invention)
Next, an example of the operation of the LAN switch 10 shown in FIGS. 1A and 1B to 4 as an embodiment of the present invention will be described in detail.

  In the LAN switch 10 of FIG. 1A, when a connection is made between the PoE down port 117 and the PoE up port 118, the connection path differs depending on whether power is supplied from the power supply circuit 115 or not. That is, when power is being supplied to each part in the LAN switch 10 via the power supply line 1151 from the power supply circuit 115, the down line 1171 connected to the PoE down port 117. And the up line 1181 connected to the PoE up port 118 are connected to the upper layer switch unit 113 via the first physical layer processing unit 111. Under the control of the control unit 114, the switch unit It is selected in 113 and set in a state of being connected to each other.

  That is, as shown in FIG. 3, communication and PoE feeding are performed in a state in which the down direction path 201 and the up direction path 202 are formed as shown by the thick double arrow in FIG. . In this state, the switch 11111 of the loopback unit 1111 in the first physical layer processing unit 111 is set to an off (open) state, and the down line 1171 connected to the PoE down port 117 and the PoE up port 118 are connected. No connection is made between the up line 1181 connected to the terminal and the return line 1111.

  Therefore, in a state where power is supplied from the power supply circuit 115, the power supplied by PoE from the upper network device, for example, the upper LAN switch 20, passes through the up direction path 202, the switch unit 113, and the down direction path 201. The PoE power is relayed to the PoE end device 30.

  On the other hand, when a failure of the power supply 116, a power failure, or the like occurs, the power supply from the power supply circuit 115 to each part in the LAN switch 10 via the power supply line 1151 occurs. The folding unit 1111 in the physical layer processing unit 111 detects a power stop and automatically sets the switch 11111 to an on (connected) state. As a result, as shown in FIGS. 2 and 4, the down line 1171 connected to the PoE down port 117 and the up line 1181 connected to the PoE up port 118 are included in the first physical layer processing unit 111. In the fold-back unit 1111, the fold-back unit 1111 is connected so as to wrap at the physical layer stage.

  That is, as illustrated in FIG. 4, a signal to be transmitted / received and PoE power are not transmitted from the first physical layer processing unit 111 to the upper switch unit 113, but are formed in a return path at the return unit 1111. In the state, that is, as shown by the thick double arrow in FIG. 4, the communication and the PoE power are relayed in the state of passing through the return route 200. As described above, in a state where power is not supplied from the power supply circuit 115, the switch 11111 of the folding unit 1111 in the first physical layer processing unit 111 is set to the on (connected) state, and the PoE down port 117 is set. The down line 1171 connected to the up line 1181 and the up line 1181 connected to the PoE up port 118 are securely connected via the return path 200 without going through the switch unit 113.

  Therefore, even when the power supply from the power supply circuit 115 is cut off, the power supplied by PoE from the higher-level network device, for example, the higher-level LAN switch 20, passes through the return path 200 to the PoE end device 30. Thus, PoE power can be reliably relayed.

  After that, when the failure of the power supply 116, power failure, or the like is restored, and the power supply from the power supply line 1151 of the power supply circuit 115 to each part in the LAN switch 10 is resumed, the first physical layer processing unit 111 The inner turning portion 1111 detects the power supply state and automatically sets the switch 11111 to the off (open) state. As a result, as shown in FIG. 3, the down line 1171 connected to the PoE down port 117 and the up line 1181 connected to the PoE up port 118 pass through the first physical layer processing unit 111. , The switch unit 113 is connected to the upper layer switch unit 113, and returns to the state of being connected to each other in the switch unit 113 under the control of the control unit 114.

(Description of the effect of the embodiment of the present invention)
As described above in detail, in the present embodiment, when the power supply of the LAN switch 10 is interrupted, the switch 11111 that is set to the on (connected) state without power supply is the first. Since the loop-back unit 1111 in the physical layer processing unit 111 is provided, there is a physical layer stage between the down line 1171 connected to the PoE down port 117 and the up line 1181 connected to the PoE up port 118. The fold-back part 1111 is connected so as to automatically wrap. Thus, even when the power supply of the LAN switch 10 is cut off, the power supplied by the PoE from the upper network device, for example, the upper LAN switch 20, can be reliably supplied to the PoE end device 30 by the PoE. The effect that can be produced.

  The configuration of the preferred embodiment of the present invention has been described above. However, it should be noted that such embodiments are merely examples of the present invention and do not limit the present invention in any way. Those skilled in the art will readily understand that various modifications and changes can be made according to a specific application without departing from the gist of the present invention.

1 network system 10 LAN switch 11 PoE pass-through 12 PoE power supply path 13 PoE power supply path 20 upper LAN switch 30 PoE end device 111 first physical layer processing unit 112 second physical layer processing unit 113 switch unit 114 control unit 115 power supply circuit 116 power supply 117 PoE down port 118 PoE up port 119 Port group 200 Return path 201 Down direction path 202 Up direction path 1111 Return section 1112 Download buffer 1113 Upload buffer 1151 Power supply line 1171 Down line 1181 Up line 11111 Switch

Claims (10)

Receiving the power supplied by the communication function and the PoE, the host network device having the communication function and the power supply function by PoE, the LAN switch having the communication function and the PoE pass-through function for relaying power by PoE A PoE end device having a function, comprising:
The LAN switch having a PoE pass-through function is:
A PoE up port for connecting to the host network device;
A PoE down port for connection to the PoE end device;
A function of performing physical layer processing on signals transmitted and received at the PoE up port and the PoE down port by connecting to the PoE up port and the PoE down port, and relaying of power received by the PoE A first physical layer processing unit having a function of performing transmission;
The first physical layer is selected between one port or a plurality of ports including the PoE down port on the lower side and between the selected port and the PoE up port on the upper side. A switch unit connected via a processing unit;
A power supply circuit connected to a power supply, and supplying power supplied from the power supply to each part to be fed,
The first physical layer processing unit determines whether or not to connect the PoE up port and the PoE down port so as to be folded back at a physical layer stage depending on whether power is supplied from the power supply circuit. A network system further comprising a turn-back unit that is automatically set. The folding unit provided in the first physical layer processing unit,
A switch is provided on a return path that connects the PoE up port and the PoE down port so as to return;
In a state where power is supplied from the power supply circuit, the switch is automatically set to an off state, and the folded path is opened.
2. The network system according to claim 1, wherein in a state in which power supply from the power supply circuit is cut off, the switch is automatically set to an on state so that the return path is connected. 3. . The folding unit provided in the first physical layer processing unit,
When the power supply from the power supply circuit is cut off, the switch is automatically set from the on state to the off state, and the return path is opened. The network system according to claim 2, wherein: One or more network terminal devices having a communication function;
The LAN switch having a PoE pass-through function is:
A port group composed of one or more ports for connecting to each of the one or more network terminal devices;
A second physical layer processing unit connected to each port of the port group and having a function of performing physical layer processing on signals to be transmitted and received is further provided. The network system described in 1. Power relay by PoE interposed between a host network device having a communication function and a function of supplying power by PoE, and a PoE end device having a communication function and a function of receiving power supplied by PoE A LAN switch having a PoE pass-through function and a communication function,
A PoE up port for connecting to the host network device;
A PoE down port for connection to the PoE end device;
A function of performing physical layer processing on signals transmitted and received at the PoE up port and the PoE down port by connecting to the PoE up port and the PoE down port, and relaying of power received by the PoE A physical layer processing unit having a function of performing transmission;
The physical layer processing unit selects any one of a plurality of ports including the PoE down port on the lower side and connects the selected port and the PoE up port on the upper side. A switch unit connected via
A power supply circuit connected to a power supply, and supplying power supplied from the power supply to each part to be fed,
The physical layer processing unit automatically determines whether or not to connect the PoE up port and the PoE down port so as to be turned back at the physical layer stage, depending on whether or not power is supplied from the power supply circuit. A LAN switch further comprising a turn-back portion set to the above. The folding unit provided in the physical layer processing unit is:
A switch is provided on a return path that connects the PoE up port and the PoE down port so as to return;
In a state where power is supplied from the power supply circuit, the switch is automatically set to an off state, and the folded path is opened.
6. The LAN switch according to claim 5, wherein in a state in which power supply from the power supply circuit is cut off, the switch is automatically set to an on state and the return path is connected. . The folding unit provided in the physical layer processing unit is:
When the power supply from the power supply circuit is cut off, the switch is automatically set from the on state to the off state, and the return path is opened. The LAN switch according to claim 6, wherein: Receiving the power supplied by the communication function and the PoE, the host network device having the communication function and the power supply function by PoE, the LAN switch having the communication function and the PoE pass-through function for relaying the power by PoE A PoE power feeding method in a network system having a PoE end device having a function,
The LAN switch having a PoE pass-through function is:
A function for performing physical layer processing on signals transmitted and received in each of the PoE up port for connecting to the upper network device and the PoE down port for connecting to the PoE end device, and receiving power by PoE A physical layer processing step having a function of performing relay transmission of the generated power;
The physical layer processing step of selecting any one of one or more ports including the PoE down port on the lower side and connecting the selected port and the PoE up port on the upper side A switch step to be connected after the processing in
A return path that connects the PoE up port and the PoE down port so as to return at the physical layer stage depending on whether or not power is supplied from a power supply circuit for supplying power to each part to be fed. A PoE feeding step for automatically determining whether or not to form a PoE power supply method. The folding step includes
In a state where power is supplied from the power supply circuit, the state is automatically set in a state where the folding path is opened,
The PoE power feeding method according to claim 8, wherein in a state in which power supply from the power supply circuit is cut off, the loopback path is automatically set to a connected state. The folding step includes
9. When the power supply from the power supply circuit is restored to a state where power supply is performed, the return path is automatically restored from the connected state to the opened state. 9. The PoE power feeding method according to 9.

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