Switching device for realizing line path switching

Abstract

The utility model discloses a switching device for realizing line path switching. The switching device comprises two circuits for realizing a single-pole double-throw switch function, each circuit comprises a switch control module, a first bias module and a first isolation module, a second bias module and a second isolation module, and a third bias module and a third isolation module; one end of the first isolation module is connected with a network interface of encryption equipment, the other end of the first isolation module is connected with one end of the first bias circuit, and the other end of the first bias circuit is connected with a common end of the switch control module; one end of the second isolation module is connected with a network interface of the first network equipment or the second network equipment, the other end of the second isolation module is connected with one end of the second bias circuit, and the other end of the second bias circuit is connected with a first free end of the switch control module; one end of the third isolation module is a straight-through path connection point, the other end of the third isolation module is connected with the third bias circuit, and the other end of the third bias circuit is connected with the second free end of the switch control module. Through the switching device for realizing line path switching provided by the embodiment of the invention, automatic switching of network level data paths is completed, and meanwhile, convenient operation and management are kept.

Description

Technical Field

[0001] The present application relates to, but is not limited to, electronic technology, and in particular to a switching device for implementing line path switching. Background Art

[0002] To ensure the security of high-reliability broadband wireless communications, the system employs an encryption module to encrypt data and prevent decryption. However, to minimize exposure to encryption during routine training, the encryption module is typically disabled to prevent electronic surveillance equipment from collecting sufficient encrypted data for decryption. Therefore, the system requires a data routing switch to direct data to an unencrypted path when encryption is not required.

[0003] Typically, packet-level routing switching can be implemented using switches or routers. However, corresponding network ports are required to support different physical connection paths. This involves hardware modifications and network port expansion, potentially increasing costs and technical complexity. To avoid the added cost of hardware network ports and device modifications, the most direct approach is to manually switch network cables—physically plugging and unplugging cables to different paths when needed. However, plugging and unplugging physical network cables requires a high level of manual labor, increasing operational complexity and hindering unified management and control. Manual operation carries the risk of delays and errors, especially in specialized high-reliability scenarios.

[0004] Therefore, there is an urgent need for a simple and efficient routing switching device that can automatically switch between encrypted and non-encrypted paths without plugging and unplugging physical network cables, while maintaining convenient operation and management. Utility Model Content

[0005] The present application provides a switching device for realizing line path switching, which can complete automatic switching of network-level data paths while maintaining convenient operation and management.

[0006] The present invention provides a switching device for implementing line path switching, including two circuits implementing single-pole double-throw switch functions; each circuit includes: a switch control module, a first bias module and a first isolation module, a second bias module and a second isolation module, and a third bias module and a third isolation module;

[0007] One end of the first isolation module is connected to the network interface of the encryption device, the other end of the first isolation module is connected to one end of the first bias circuit, and the other end of the first bias circuit is connected to the common end of the switch control module; one end of the second isolation module is connected to the network interface of the first network device or the second network device, the other end of the second isolation module is connected to one end of the second bias circuit, and the other end of the second bias circuit is connected to the first free end of the switch control module; one end of the third isolation module is a through path connection point, the other end of the third isolation module is connected to the third bias circuit, and the other end of the third bias circuit is connected to the second free end of the switch control module;

[0008] When the common end of the switch control module is connected to the first free end, the first bias module and the second bias module are used to set the DC operating point of the signal switch in the first bias module so that the signal switch in the first bias module is forward biased and turned on, and the signal switch in the third bias module is reverse biased and turned off, and the line between the first network device or the second network device and the encryption device is connected;

[0009] When the common end of the switch control module is connected to the second free end, the third bias module and the second bias module are used to set the DC operating point of the signal switching switch in the third bias module, so that the signal switching switch in the third bias module is forward biased and turned on, and at the same time, the signal switching switch in the first bias module is reverse biased and turned off, so that the first network device or the second network device is directly connected to the second network device or the first network device.

[0010] In an exemplary embodiment, the first isolation module or the second isolation module or the third isolation module includes: a network transformer and a DC blocking capacitor;

[0011] Among them, the network transformer is used to achieve line isolation and impedance matching functions; the DC blocking capacitor is used to block DC.

[0012] In an exemplary embodiment, the first bias module or the second bias module or the third bias module includes: a bias resistor, a switching diode;

[0013] The bias resistor is used to set a suitable DC operating point for the switching diode; the switching diode is used to be forward biased to turn on or reverse biased to turn off at the set DC operating point.

[0014] In an exemplary embodiment, the switching diode is a high-frequency switching diode.

[0015] In an exemplary embodiment, the switch control module is a double-pole double-throw switch.

[0016] In an exemplary embodiment, the double-pole double-throw switch is controlled manually or by a relay.

[0017] In an exemplary embodiment, the switch control module includes two common terminals;

[0018] The first common terminal of the switch control module is connected to the first bias module, the first free end corresponding to the first common terminal is connected to the positive electrode of the power supply, and the second free end corresponding to the first common terminal is grounded through a bias resistor; the second common terminal of the switch control module is connected to the third bias module, the first free end corresponding to the second common terminal is connected to the positive electrode of the power supply, and the second free end corresponding to the second common terminal is grounded through a bias resistor.

[0019] In an exemplary embodiment, when the first common end of the switch control module is connected to its corresponding first free end, the DC operating point of the signal switching switch in the first bias module is set so that the signal switching switch in the first bias module is forward biased and turned on, while the signal switching switch in the third bias module is reverse biased and turned off, and the line between the first network device and the encryption device is connected, so that the first network device and the second network device are connected through an encrypted path;

[0020] When the first common end of the switch control module is connected to its corresponding second free end, the DC operating point of the signal switching switch in the third bias module is set so that the signal switching switch in the third bias module is forward biased and turned on, while the signal switching switch in the first bias module is reverse biased and turned off, so that the first network device is connected to the direct path connection point, so that the first network device and the second network device are directly connected;

[0021] When the second common end of the switch control module is connected to the corresponding first free end, the DC operating point of the signal switch in the second bias module is set so that the signal switch in the second bias module is forward biased and turned on, and at the same time, the signal switch in the third bias module is reverse biased and turned off, and the line between the first network device and the encryption device is connected, so that the first network device and the second network device are connected through an encrypted path;

[0022] When the second common end of the switch control module is connected to its corresponding second free end, the DC operating point of the signal switching switch in the third bias module is set so that the signal switching switch in the third bias module is forward biased and turned on, while the signal switching switch in the second bias module is reverse biased and turned off, and the first network device is connected to the direct path connection point, so that the first network device and the second network device are directly connected.

[0023] By implementing the switching device for line path switching provided in the embodiment of the present application, automatic switching of network-level data paths is achieved while maintaining convenient operation and management.

[0024] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or understood by practicing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to provide a further understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0026] Figure 1 This is an example diagram of an application scenario in which a switch or router is used to implement packet-level routing switching in an embodiment of the present application;

[0027] Figure 2 Schematic diagram of the structure of a switching device for implementing line path switching in an embodiment of the present application that implements an SPDT switch function;

[0028] Figure 3 A schematic diagram of the principle of applying the switching device in an embodiment of the present application to an application scenario of implementing routing switching at the data packet level;

[0029] Figure 4 Schematic diagram of a circuit of a switching device in an embodiment of the present application. DETAILED DESCRIPTION

[0030] To make the purpose, technical solutions and advantages of this application more clear, the embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be noted that, unless there is a conflict, the embodiments and features in the embodiments of this application can be combined with each other in any way.

[0031] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0033] It should be understood that the terms "first" and "second" used in this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0034] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if there is transmission of electrical signals or data between the connected circuits, modules, units, etc.

[0035] As used herein, the singular forms "a," "an," and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include," "comprising," "having," and the like specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Furthermore, the term "and / or" as used in this specification includes any and all combinations of the relevant listed items.

[0036] Figure 1 This is an example diagram of an application scenario in which a switch or router is used to implement packet-level routing switching in an embodiment of the present application. Figure 1 The figure shows the switching principle of data path switching at the network layer. Data path switching is used to switch the data path between two network devices (such as an application layer device and a wireless device). One data path is a straight-through path (i.e., a non-encrypted path), which directly connects the application layer device and the wireless device, providing uninterrupted data transmission. The other data path is an encrypted path, and the encryption device is located between the data communication network ports of the two network devices (such as the application layer device and the wireless device).

[0037] Figure 1 In the switch, the switching device consists of two parts that realize the function of single-pole double-throw switch (SPDT switch), such as Figure 1 The first and second SPDT switches K11 and K12 in the IEEE 802.11 protocol are used to switch the data path between a straight-through path and an encrypted path. When both switches select the straight-through path, data is transmitted directly between the application layer device and the wireless device without being processed by the encryption device. When both switches select the encrypted path, data is processed by the encryption device (possibly decrypted, encrypted, or otherwise securely processed) before reaching the destination device.

[0038] Figure 2Schematic diagram of the structure of a switching device for implementing line path switching in an embodiment of the present application, which implements the SPDT switch function. Figure 2 Demonstrated implementation Figure 1 The circuit principle module of the first single-pole double-throw switch K11 or the second single-pole double-throw switch K12, that is, the switching device for realizing line path switching in the embodiment of the present application includes two circuits realizing the function of single-pole double-throw switches, such as Figure 2 As shown, each circuit includes at least: a switch control module, a first bias module and a first isolation module, a second bias module and a second isolation module, a third bias module and a third isolation module;

[0039] Among them, one end of the first isolation module is connected to the network interface of the encryption device, the other end of the first isolation module is connected to one end of the first bias circuit, and the other end of the first bias circuit is connected to the common end of the switch control module; one end of the second isolation module is connected to the network interface of the first network device / second network device (such as an application layer device / wireless device), the other end of the second isolation module is connected to one end of the second bias circuit, and the other end of the second bias circuit is connected to the first free end of the switch control module; one end of the third isolation module is a straight-through path connection point, the other end of the third isolation module is connected to the third bias circuit, and the other end of the third bias circuit is connected to the second free end of the switch control module.

[0040] The first isolation module, the second isolation module, and the third isolation module are respectively used to isolate the lines where they are located and to cut off direct current;

[0041] When the common end of the switch control module is connected to the first free end, the first bias module and the second bias module are used to set the DC operating point of the signal switch in the first bias module so that the signal switch in the first bias module is forward biased and turned on, while the signal switch in the third bias module is reverse biased and turned off, and the line between the first network device / the second network device (such as the application layer device / the wireless device) and the encryption device is connected (i.e., the encryption path is connected);

[0042] When the common end of the switch control module is connected to the second free end, the third bias module and the second bias module are used to set the DC operating point of the signal switching switch in the third bias module, so that the signal switching switch in the third bias module is forward biased and turned on, and at the same time, the signal switching switch in the first bias module is reverse biased and turned off, so that the first network device / second network device (such as application layer device / wireless device) and the second network device / first network device (such as wireless device / application layer device) are directly connected (i.e., connected via a non-encrypted path).

[0043] In an exemplary embodiment, the signal switching switch in the bias module may be a high-frequency switching diode, and the signal path is turned on or off by turning on or off the high-frequency diode.

[0044] In one exemplary embodiment, the first, second, or third isolation modules may include a network transformer and a DC-blocking capacitor. The network transformer is used to implement line isolation and also performs impedance matching. The DC-blocking capacitor is used to block DC and allow only AC signals to pass. The specific implementation circuits of the isolation modules are not intended to limit the scope of protection of this application.

[0045] In one exemplary embodiment, the first bias module, the second bias module, or the third bias module may include: a bias resistor and a high-frequency switching diode; wherein the bias resistor is used to set a suitable DC operating point for the high-frequency switching diode; and the high-frequency switching diode is used to forward bias the diode to conduct or reverse bias the diode to shut down at the set DC operating point. The specific implementation circuit of the bias module is not intended to limit the scope of protection of this application.

[0046] In an exemplary embodiment, the switch control module can be a double-pole double-throw switch. In an embodiment, the switch control module can be controlled manually or by a relay.

[0047] In one embodiment, the switch control module includes two common terminals. One common terminal of the switch control module (referred to as the first common terminal) is connected to the first bias module, a first free terminal corresponding to the first common terminal is connected to the positive pole of the power supply, and a second free terminal corresponding to the first common terminal is grounded via a bias resistor. The other common terminal of the switch control module (referred to as the second common terminal) is connected to the third bias module, a first free terminal corresponding to the second common terminal is connected to the positive pole of the power supply, and a second free terminal corresponding to the second common terminal is grounded via a bias resistor.

[0048] By implementing the switching device for line path switching provided in the embodiment of the present application, automatic switching of network-level data paths is achieved while maintaining convenient operation and management.

[0049] Figure 3 FIG. 1 is a schematic diagram showing the principle of applying the switching device in the embodiment of the present application to an application scenario of implementing routing switching at the packet level. Figure 3 As shown, the implementation of the first single-pole double-throw switch K11 includes: an isolation module 211, a bias module 212, an isolation module 111, a bias module 112, an isolation module 311, a bias module 312, and a switch control module 11; the implementation of the second single-pole double-throw switch K12 includes: an isolation module 221, a bias module 222, an isolation module 121, a bias module 122, an isolation module 321, a bias module 322, and a switch control module 22.

[0050] When the common end of the switch control module 11 is connected to the first free end, the DC operating point of the signal switching switch in the bias module 111 is set so that the signal switching switch in the bias module 111 is forward biased and turned on, while the signal switching switch in the bias module 312 is reverse biased and turned off. The line between the first network device (such as the application layer device) and the encryption device is connected (i.e., the encryption path is connected). In this way, the first network device (such as the application layer device) and the second network device (such as the wireless device) are connected via the encryption path.

[0051] When the common end of the switch control module 11 is connected to the second free end, the DC operating point of the signal switching switch in the bias module 312 is set so that the signal switching switch in the bias module 312 is forward biased and turned on, while the signal switching switch in the bias module 111 is reverse biased and turned off, and the first network device (such as the application layer device) is connected to the direct path connection point (i.e., the non-encrypted path is connected). In this way, the first network device (such as the application layer device) and the second network device (such as the wireless device) are directly connected.

[0052] When the common end of the switch control module 22 is connected to the first free end, the DC operating point of the signal switching switch in the bias module 121 is set so that the signal switching switch in the bias module 121 is forward biased and turned on, while the signal switching switch in the bias module 322 is reverse biased and turned off. The line between the first network device (such as the application layer device) and the encryption device is connected (i.e., the encryption path is connected). In this way, the first network device (such as the application layer device) and the second network device (such as the wireless device) are connected via the encryption path.

[0053] When the common end of the switch control module 22 is connected to the second free end, the DC operating point of the signal switching switch in the bias module 322 is set so that the signal switching switch in the bias module 322 is forward biased and turned on, while the signal switching switch in the bias module 121 is reverse biased and turned off, and the first network device (such as the application layer device) is connected to the direct path connection point (i.e., the non-encrypted path is connected). In this way, the first network device (such as the application layer device) and the second network device (such as the wireless device) are directly connected.

[0054] Figure 4 This is a circuit diagram of an embodiment of a switching device in an embodiment of the present application. Figure 4 Only one single-pole double-throw switch in the switching device is shown in the circuit diagram. The circuit diagram of the other single-pole double-throw switch is the same as that of the Figure 4 consistent, and Figure 4 This is only a specific circuit implementation example and is not intended to limit the scope of protection of this application. Figure 4 and Figure 2 The analysis is as follows:

[0055] Transformer T1, transformer T2, and transformer T3 are network transformers used to achieve line isolation and provide impedance matching to make signal transmission more stable.

[0056] Capacitors C1, C2, C3, C4, C5, C6, and C7 are DC blocking capacitors used to block DC components and only allow AC signals to pass through, thereby ensuring the effectiveness of signal transmission.

[0057] Capacitors C8 and C9 are decoupling capacitors used to filter out ripple in the power supply, provide a smoother DC power supply, and prevent the signal from being interfered with by the power supply ripple. It should be noted that decoupling capacitors are optional and whether or not decoupling capacitors are provided does not limit the scope of protection of this application.

[0058] Diode D1 , diode D2 , diode D3 , and diode D4 are high-frequency switching diodes used to control the on or off of a signal path, and to achieve forward bias or reverse bias of the diodes according to the setting of the bias resistors.

[0059] Resistors R1, R2, R3, R4, R5, R6, R7, and R8 are bias resistors used to set the DC operating point of the diode to ensure that the diode is forward biased and turned on when needed, and reverse biased and turned off when not needed.

[0060] Switch K1 is a double-pole double-throw switch (DPDT), which is used to control the direction of the signal path. It can be controlled manually or by relays to switch the network cable signal between different paths.

[0061] Combine Figure 2 Transformer T1, capacitor C1, capacitor C4, and capacitor C5 form a first isolation module; transformer T2 and capacitor C2 form a second isolation module; transformer T3, capacitor C3, capacitor C6, and capacitor C7 form a third isolation module. Switch K1, resistor R7, resistor R8, and power supply Vcc+ form a switch control module. Resistors R1, R2, diode D1, and D2 form a first bias circuit; resistors R5, R6, diode D3, and D4 form a third bias circuit. In the second bias circuit composed of resistors R3, R4, and diodes, the diodes can include diodes D1 and D2, or diodes D3 and D4.

[0062] Figure 4 The functional analysis of the circuit shown is as follows:

[0063] When switch K1 is turned upward, both common terminals of switch K1 are connected to their respective corresponding first free terminals. At this time, the first free terminal corresponding to the first common terminal of switch K1 is connected to the positive electrode of the power supply Vcc+, and the first free terminal corresponding to the second common terminal is grounded through resistor R8. The positive electrode of the power supply Vcc+ is grounded through resistor R1, diode D1, and resistor R3, as well as resistor R2, diode D2, and resistor R4. This causes diodes D1 and D2 to be forward biased and turned on, and the network cable signal can be communicated through transformer T1 and transformer T2. At the same time, the first free terminal corresponding to the second common terminal of switch K1 is grounded through resistor R8, causing diodes D3 and D4 to be reverse biased and turned off, isolating the signal of transformer T3 and disconnecting the line between transformer T3 and transformer T2.

[0064] When switch K1 is turned downward, both common terminals of switch K1 are connected to their respective corresponding second free terminals. At this time, the first free terminal corresponding to the second common terminal of switch K1 is connected to the positive electrode of the power supply Vcc+, and the first free terminal corresponding to the first common terminal is grounded through resistor R7. The positive electrode of the power supply Vcc+ is grounded through resistor R5, diode D3, and resistor R3, as well as resistor R6, diode D4, and resistor R4, so that diodes D3 and D4 are forward biased and turned on, and the network cable signal can be communicated through transformer T3 and transformer T2. At the same time, the first free terminal corresponding to the first common terminal of switch K1 is grounded through resistor R7, so that diodes D1 and D2 are reverse biased and turned off, isolating the signal of transformer T1 and disconnecting the line between transformer T1 and transformer T2.

[0065] like Figure 4 As shown, by switching the switch K1, network cable signals can be communicated between transformers T1 and T2, or between transformers T3 and T2, thereby achieving flexible switching of network cable signal paths. The switching device provided in the embodiment of the present application is suitable for application scenarios where signal paths need to be switched between different network devices.

[0066] Because network line signals are high-speed, broadband analog signals—taking a typical 100M network as an example, the analog signal base frequency reaches 125MHz—and require minimal signal loss, distortion, bandwidth, and group delay fluctuations, the switching device provided in this embodiment utilizes an analog RF broadband circuit design and selects appropriate high-frequency switching diodes to ensure signal waveform quality. This avoids the severe damage to the signal waveform caused by conventional relay switching, resulting in poor signal quality, increased packet error rates at network ports, and even network disconnection. Furthermore, the network cable switching function was verified to be normal using Ethernet equipment, passing environmental reliability tests.

[0067] The switching device provided in the embodiment of the present application is a simple and efficient routing switching device that completes automatic switching between encrypted paths and non-encrypted paths without the need to plug in or unplug physical network cables, while maintaining convenient operation and management.

[0068] Although the embodiments disclosed in this application are as described above, the contents described are merely embodiments adopted to facilitate understanding of this application and are not intended to limit this application. Any person skilled in the art to which this application belongs may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in this application. However, the scope of patent protection of this application shall still be based on the scope defined by the attached claims.

Claims

1. A switching device for realizing line path switching, characterized in that: It includes two circuits for realizing the function of single-pole double-throw switch; each circuit includes: a switch control module, a first bias module and a first isolation module, a second bias module and a second isolation module, a third bias module and a third isolation module; One end of the first isolation module is connected to the network interface of the encryption device, the other end of the first isolation module is connected to one end of the first bias circuit, and the other end of the first bias circuit is connected to the common end of the switch control module; one end of the second isolation module is connected to the network interface of the first network device or the second network device, the other end of the second isolation module is connected to one end of the second bias circuit, and the other end of the second bias circuit is connected to the first free end of the switch control module; one end of the third isolation module is a through path connection point, the other end of the third isolation module is connected to the third bias circuit, and the other end of the third bias circuit is connected to the second free end of the switch control module; When the common end of the switch control module is connected to the first free end, the first bias module and the second bias module are used to set the DC operating point of the signal switch in the first bias module so that the signal switch in the first bias module is forward biased and turned on, and the signal switch in the third bias module is reverse biased and turned off, and the line between the first network device or the second network device and the encryption device is connected; When the common end of the switch control module is connected to the second free end, the third bias module and the second bias module are used to set the DC operating point of the signal switching switch in the third bias module, so that the signal switching switch in the third bias module is forward biased and turned on, and at the same time, the signal switching switch in the first bias module is reverse biased and turned off, so that the first network device or the second network device is directly connected to the second network device or the first network device.

2. The switching device according to claim 1, wherein: The first isolation module, the second isolation module, or the third isolation module includes: a network transformer and a DC blocking capacitor; Among them, the network transformer is used to achieve line isolation and impedance matching functions; the DC blocking capacitor is used to block DC.

3. The switching device according to claim 1, wherein: The first bias module, the second bias module, or the third bias module includes: a bias resistor and a switching diode; The bias resistor is used to set a suitable DC operating point for the switching diode; the switching diode is used to be forward biased to turn on or reverse biased to turn off at the set DC operating point.

4. The switching device according to claim 3, wherein: The switching diode is a high-frequency switching diode.

5. The switching device according to claim 1, wherein: The switch control module is a double-pole double-throw switch. The switching device according to claim 5 , wherein: The double-pole double-throw switch is controlled manually or by a relay.

7. The switching device according to claim 5, wherein: The switch control module includes two common terminals; The first common terminal of the switch control module is connected to the first bias module, the first free end corresponding to the first common terminal is connected to the positive electrode of the power supply, and the second free end corresponding to the first common terminal is grounded through a bias resistor; the second common terminal of the switch control module is connected to the third bias module, the first free end corresponding to the second common terminal is connected to the positive electrode of the power supply, and the second free end corresponding to the second common terminal is grounded through a bias resistor.

8. The switching device according to claim 7, wherein: When the first common end of the switch control module is connected to its corresponding first free end, the DC operating point of the signal switching switch in the first bias module is set so that the signal switching switch in the first bias module is forward biased and turned on, and at the same time, the signal switching switch in the third bias module is reverse biased and turned off, and the line between the first network device and the encryption device is connected, so that the first network device and the second network device are connected through an encrypted path; When the first common end of the switch control module is connected to its corresponding second free end, the DC operating point of the signal switching switch in the third bias module is set so that the signal switching switch in the third bias module is forward biased and turned on, while the signal switching switch in the first bias module is reverse biased and turned off, so that the first network device is connected to the direct path connection point, so that the first network device and the second network device are directly connected; When the second common end of the switch control module is connected to the corresponding first free end, the DC operating point of the signal switch in the second bias module is set so that the signal switch in the second bias module is forward biased and turned on, and at the same time, the signal switch in the third bias module is reverse biased and turned off, and the line between the first network device and the encryption device is connected, so that the first network device and the second network device are connected through an encrypted path; When the second common end of the switch control module is connected to its corresponding second free end, the DC operating point of the signal switching switch in the third bias module is set so that the signal switching switch in the third bias module is forward biased and turned on, while the signal switching switch in the second bias module is reverse biased and turned off, and the first network device is connected to the direct path connection point, so that the first network device and the second network device are directly connected.

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