CN102387051B - Automatic switching network extension device and switching method - Google Patents

Abstract

The invention discloses an automatic switching network extension device and a switching method, in particular to an automatic connection mechanism which is used for realizing the purpose of automatic connection after trying to connect with another network extension device by using a numerical value generated by a random number as a basis for setting a device as a local side or a user side working mode. According to the embodiment, after the automatic switching type network extension device is initialized, a group of connection parameters and a setting code generated by using a random number are generated, the device automatically sets a working mode according to the setting code, after the working mode of the other network extension device is detected, if the working mode of the device is different from the working mode of the device, the connection can be realized, otherwise, the random number is continuously used for generating a setting value to execute the setting until the connection is realized. The invention can be applied to the laid telephone line for network connection by using a labor-saving and convenient connection mode, and can easily expand more than two area networks.

Description

Automatic switching network extension device and switching method

technical field

The invention relates to an automatic switching network extension device and a switching method, in particular to a network extension device which automatically switches functions by detecting the working role of another network extension device through data packets.

Background technique

Very High Data Rate DSL (VDSL), which is often used outdoors, is the fastest xDSL technology at present. When performing bidirectional constant-speed symmetrical transmission, the transmission rate mainly changes according to the length of the line. The ultra-high-speed digital subscriber loop is mainly used in the signal transmission of the optical fiber digital network.

As shown in Figure 1, the existing network architecture diagram of the VDSL system is divided into two ends: the user end X (such as a home user) and the central office Y (such as a telecommunications company). The two network devices are connected, that is, the customer premises equipment (Customers Premises Equipment, CPE) 11 and the central office transmission equipment (Center Office, CO) 12 are connected by this telephone copper cable 101, and the cable can carry voice at the same time Signal (voice) and data signal (data), VDSL technology can not only provide high-speed data transmission, but also carry telephone voice data.

In the embodiment of the VDSL system shown in Fig. 1, the user terminal transmission device 11 is responsible for the function of signal splitting (splitting), which can separate the data and voice signals carried on the telephone copper cable 101, such as separately carrying data and voice signals. Filtering is performed on the high and low frequency signals of speech. The user end transmission device 11 can separate the voice signal, and then transmit it to the connected indoor phone 13 , relatively, the voice signal is transmitted to the central office Y through the user end transmission device 11 through the indoor phone 13 .

The user terminal transmission device 11 also transmits data to a symmetrical digital subscriber circuit remote unit (ADSL Tranceiver Unit Remote, ATU-R) 14, performs data signal analog-to-digital conversion, signal demodulation (demodulate), and provides network services to users terminal computer 15 . Correspondingly, the user also transmits the digital signal through the computer 15 to the user terminal transmission device 11 through the symmetrical digital subscriber circuit remote unit (ATU-R) 14, and then to the central office Y. In operation, the signal splitting function of the client transmission device 11 is to simultaneously carry voice and data through the carrier, and to receive voice and data at the same time, and then separate them for different applications.

Similarly, the equipment at the central office Y is connected to the user end transmission device 11 of the user terminal X through the central office transmission device 12, and the central office transmission device 12 is also responsible for the function of signal divergence, and the voice and data signals transmitted with the user terminal X Separately, the voice signal is connected to the public switched telephone network (PSTN) 18 via a voice switch 16 . On the other hand, the data signal separated by the central office transmission device 12 is transmitted to a DSL access multiplexer (DSL access multiplexer, DSLAM) 17, and the DSL access multiplexer 17 can effectively integrate the IP network and the image The ATM network 19 shown, and finally delivered to the Internet service provider (ISP) 191 or enterprise 193. Similar to the above-mentioned user end transmission device 11, the signal splitting function of the central office end transmission device 12 is also to combine voice and data for transmission, or to separate voice and data after receiving.

In the above-mentioned VDSL system, the user end X and the central office Y use transmission devices (11, 12) with different branch functions to connect with the generally laid telephone copper axis cable 101, but to form an ultra-high-speed digital subscriber circuit The system is implemented by setting up a master (master) transmission device at the local end and a slave (slave) user end transmission device at both ends of the signal transmission.

Generally speaking, optical fiber cables can be used to achieve ultra-high-speed transmission. However, in the VDSL system, high-speed transmission capabilities can be achieved on ordinary telephone copper cables, and it is responsible for voice and data bearing operations.

On the VDSL network, it is especially necessary to establish connections with equipment such as the central office (CO) and the customer end (CPE), and the filtering methods of the two are different.

Contents of the invention

The purpose of the present invention is to utilize the characteristics of the existing VDSL transmission, and further use a new hybrid filtering method to integrate the transmission devices of the central office and the user end into a single device, and then use the mechanism of automatic connection to automatically Switch between the central office (CO) working mode as the master (master) or the customer end (CPE) working mode as the slave (slave).

Because the filtering methods in the above-mentioned user end and the central office transmission device are different, two sets of different circuits should be required for combination. The present invention also proposes an integrated signal processing chip for integrated data processing, central office and user end filtering function, using this integrated chip to cooperate with a local end and user end (CO/CPE) circuit switching unit, so that the switching unit enables this single device to perform the transmission function of the CO end or the CPE end. In particular, the automatic connection procedure can also quickly and conveniently realize the connection with the remote device, without the need for staff to go to the site to set up.

In order to achieve the purpose of having the signal divergence function between the central office and the user end at the same time in a single device, one of the embodiments includes the above-mentioned integrated signal processing chip, which provides at least two types of input and output connection ports through the communication port connection unit, and is connected to provide manual Or an automatic function switching mechanism, including an automatic switching unit and a switching switch for performing automatic connection. There is also a display unit, which can display the current working status of the device through a light signal or a display.

Another embodiment is that a single device is integrated with a data processing unit electrically connected to each other, a hybrid central office and user end (CO/CPE) signal filter unit, an output line filter unit, and RJ-45, RJ-11 The communication port connection unit for the input and output interfaces, the automatic switching unit for executing the automatic connection program, the status display unit for displaying the working mode, and the communication port controller for network detection. In addition, it can have a local end-automatic detection-client end (CO/AUTO/CPE) switching switch to realize hardware function switching.

Among them, the data processing unit executes the signal exchange of each circuit unit, the local end and the user end circuit switching unit switch the transmission circuit between the local end and the user end, and then filter the signal through the output line filter unit, and then provide various communication ports, etc. The communication port connection units of the input and output interfaces are respectively connected to a network and connected to another network extension device. The status display unit displays the status lights or displays the working status on the screen,

In particular, the present invention sets an automatic switching unit for executing the automatic connection program in the device, which can generate a switching signal manually or automatically, and set the device in the central office or user end working mode.

According to the embodiment, the above-mentioned circuit components are used to realize the automatic switching and connection program of the present invention. When the automatic switching network extension device is started, the internal circuit will perform an initialization setting, except for driving the internal circuit components and activating the communication ports. , can set the working mode through the automatic switching unit, generate connection parameters, and automatically connect with another network extension device.

When the steps generate connection parameters, especially through a random number generator to generate a setting code, set the relative working mode according to the odd or even number, try to connect with the device at the other end, if the connection fails, it can automatically pass through repeat steps to connect.

The beneficial effect of the present invention is that, in summary, the main feature of the automatic switching network extension device disclosed in the present invention is to use an automatic connection program to automatically set the network extension device at the central office or user end and remote The device is connected, so that the device can use the labor-saving and convenient connection method to apply to the laid telephone line for network connection, and can easily expand more than two regional networks.

Description of drawings

Fig. 1 shows the prior art network architecture diagram of the VDSL system;

Fig. 2 is a schematic diagram of an embodiment of the present invention applied between buildings;

3A to 3C are schematic diagrams of embodiments of the panel of the network extension device of the present invention;

FIG. 4A shows a circuit block diagram of one embodiment of the network extension device of the present invention;

FIG. 4B is a circuit block diagram of Embodiment 2 of the network extension device of the present invention;

Fig. 5 is shown as one of the flow charts of the automatic connection program of the present invention;

Fig. 6 shows the second flow chart of the automatic connection program of the present invention.

Wherein, the reference signs are explained as follows:

Client X Central Office Y

Telephone copper axis cable 101 User terminal transmission device 11

Central office transmission device 12 Indoor telephone 13

Symmetrical Digital Subscriber Loop Remote Unit 14

Computer 15 Voice Switcher 16

DSL Access Multiplexer 17 Public Switched Telephone Network 18

ATM Network 19 Network Service Provider 191

Enterprise 193 Building A, B

The first network extension device 21 The second network extension device 22

Switch 23, 25 Line 201

Network cable 203, 205 Network extension device 30

Selector switch 301 Power socket 303

Ethernet port 305, 305’ Telephone line port 307

Status display light number 309 Data processing unit 401

Local end and user end signal filter unit 403 output line filter unit 405

Communication port connection unit 407 Automatic switching unit 409

Status display unit 413 Communication port controller 415

Central office-automatic detection-client switching switch 411

Integrated signal processing unit 40

Steps S501-S509 are one of the automatic connection program steps

Steps S601 ~ S607 The second step of the automatic connection procedure

Detailed ways

According to an embodiment, the technology proposed by the present invention is especially applied to a circuit with a loop mechanism for switching the central office (CO side) and the customer side (CPE side) in a single device, which operates as a network extension connecting the two networks The device (extension apparatus), the device has at least two connection ports, and the main embodiment is (but not limited to) connecting the local area network based on the Ethernet and the wide area network with the telephone network as the main connection means.

The main feature of the network extension device is to design the lines of the user end and the central office in the prior art in a single device, especially introduce an automatic switching function mechanism, including a function that can be set by a switching switch, or No toggle switches are provided, and the presets can be run with auto-switch functionality. Among them, at least one chip set (chipset) command performs function switching, which is mainly to execute an automatic connection program according to the automatic switching command or switching signal, and the chip set then sets the filtering means of the user end and the local end to realize the purpose of automatic switching .

Reference can be made to the implementation shown in Figure 2, in which two buildings A and B represent two regional networks, where users use network cables (such as RJ-45) 203, 205 to connect to switches (or routers) in the regional network 23, 25, so as to connect to the external network. In this example, the local area networks where building A and building B are located each have a network extension device, namely the first network extension device 21 and the second network extension device 22, and the two network extension devices are connected to each other through the line 201 For the area network at both ends, this line can use the RJ-11 specification line, which usually has the characteristics of long-distance transmission. Under the condition of using ordinary telephone copper wire, the transmission rate of 30Mbps can be effectively implemented at a distance of more than 600 meters at both ends, without the need to use new cables to change the 100-meter limit of the Ethernet network.

The first network extension device 21 and the second network extension device 22 can operate as a central office (CO end) or a user end (CPE end) to form a point-to-point connection structure. The working roles of these two network extension devices can be manually set at the beginning of the network setting up the circuit and filtering means, one is running as a network extension device at the central office, and the other is running as a network extension device at the user end. They are connected by line 201 and exchange data packets. The Ethernet ports on the above-mentioned two network extension devices 21 and 22 are through switches or other devices with network signal exchange capabilities, such as routers (routers), hubs (hubs), etc., so that buildings A and B The regional network is connected into a regional network by wired (or wireless) means.

Related technologies can refer to the "switchable VDSL central office user end loop network extension device" proposed by the same applicant of the present invention (China Taiwan Patent Publication No. 200830851, application number: 096100986), wherein the disclosed switchable VDSL office The network extension device of the end-user loop can switch the loop through a switch, so that it can operate as a network extension device at the central office or a network extension device at the user end.

The present invention further proposes a network extension device with an automatic switching mechanism. When two network extension devices are connected to each other, especially the devices located at both ends beyond a certain distance, there is no need to use manual settings, and the internal mechanism of the device will automatically Connect the program to adjust the work roles, and set your own work role as the central office or client network extension device.

Continuing to refer to FIG. 3A to FIG. 3C , schematic diagrams of an embodiment of the panel of the network extension device of the present invention are shown, including various connection ports, switching switches and status lights.

3A shows one side of the panel of the network extension device 30. In this example, the panel has a selection switch 301 and a power socket 303 connected to a power source. The user can select a function by switching the selection switch 301. In this embodiment, the selection The functions include Loc (local end), Rmt (user end) and AUTO (automatic detection) in the figure. When manually switching to Loc, the switching circuit makes the device switch to the central office network extension device; if switching to Rmt, switch the device to a network extension device on the client side. In particular, if it is switched to AUTO, the device will automatically switch to the work role that the device should have in order to execute the automatic connection program, that is, after detecting that the network extension device 30 at the other end of the connection is set as the central office device, then the It will be automatically set as the client device; otherwise, if the other end is the client device, it will be automatically set as the central office device.

The above-mentioned FIG. 3A describes one of the embodiments of the present invention, but it is not limited to this embodiment. Other embodiments include manually setting the control circuit in the device to the local end mode (CO mode) or the user end mode (CPE mode), and the above-mentioned utilization The switch selects the mode of manual or automatic switching. Another embodiment can be a fully automatic mode. The device itself is preset to automatically set the local end or user end mode. There is no switch, and only a light or a display represents the current state. Operating mode.

In the embodiment set to the automatic mode, when the network extension devices at both ends are set to AUTO, generally speaking, if it is judged that there is no device with other roles on the network, it will be automatically set as the network extension of the central office or the user end The device 30 (for example, determines the working mode according to a random number mechanism, refer to the flow shown in FIG. 6 ). After one device determines the working mode, another network extension device automatically sets to another working mode because it recognizes that there is already a central office or a client terminal on the network.

Since each network extension device is a device for bridging the local area network and another network, it has a variety of communication ports shown in another panel embodiment as shown in Figure 3B. This example shows an Ethernet port 305 using RJ-45 specifications and using The telephone line port 307 of RJ-11 specification, the network extension device of the present invention is not limited to these two types of communication ports, but can be applied to various types of packet collision network types. In this preferred embodiment of the present invention, the Ethernet port 305 is connected to the interface device of the internal network, including network devices such as a router (router), a switch (switch), and a hub (hub), while the telephone line port 307 is Connect to the telephone line port of another network extension device 30 to realize the purpose of connecting two or more local area networks. For an embodiment of the connection relationship, refer to FIG. 2 .

In this example, the panel of the network extension device 30 is also provided with a status display light 309 including a plurality of lights (such as LEDs, another embodiment can be a display screen), in addition to displaying the network connection, device operation, and power supply status. The status of the network extension device can also display the working mode of the network extension device, that is, the status of the network extension device at the central office or the client end after automatic setting is indicated by a light or a display screen.

In another embodiment, the panel embodiment shown in FIG. 3C has at least one telephone line port 307, and two or more Ethernet ports 305 and 305'. At this time, the device disclosed in this embodiment can be Serve as a network switch (switch) function. The telephone line port 307 can be used to connect to other networks extended by the network extension device 30 of the present invention, and a plurality of Ethernet ports (305, 305') can be used to connect multiple internal network devices. The status display light 309 can also display the status of network connection, device operation, power supply situation, job role and so on.

The above-mentioned technique of controlling the loop between the local end and the user end by means of a switching switch mainly uses a control circuit (such as a control IC) to switch the loop according to a switching signal. An embodiment may refer to FIG. 4A .

In order to achieve the purpose of having the signal divergence function of the central office and the user end at the same time in a single device, according to the diagram, it is shown that an integrated signal processing unit 40 is provided in a single device, which is mainly integrated with integrated circuit (IC) technology. The signal processing in the device and the filtering functions of the central office and the user end include the signal processing between each input and output data packet and each unit circuit in the device, and perform the function of switching the signal filtering between the central office and the user end.

The network extension device generates a setting value through the automatic switching unit 409, and executes an automatic connection procedure. This setting value can be automatically set according to the detection of the working mode of the network extension device at the other end of the network, or manually switched by the user function, such as using the central office-automatic detection-client end (CO/AUTO/CPE) switch 411 hardware switch. The network extension device operates in a central office mode or a client mode according to the set value. The network extension device provides various external connection ports such as RJ-45 and RJ-11 through the communication port connection unit 407 to connect another network extension device with other networks.

The integrated signal processing unit 40 is used to carry out the signal exchange of each circuit unit in the automatic switching network extension device, and is electrically connected to the above-mentioned automatic switching unit 409, and can perform local-side work mode or user-side work according to the set value mode and perform data processing to and from another network extension device. The communication port controller 415 is used to detect the working mode of another network extension device on the network. The present invention further provides a status display unit 413 capable of displaying the working mode of the device.

According to another embodiment, the network extension device of the present invention introduces a hybrid filter unit (Hybrid Filter) that performs loop switching according to the automatic switching signal, and can perform different signal filtering. A schematic diagram is shown in Figure 4B.

The network extension device of the present invention includes at least the circuit units described in FIG. 4B . Compared with the signal processing and filtering functions of the integrated signal processing unit 40 integrated in FIG. 4A , this embodiment uses data processing units that are electrically connected to each other. 401. Hybrid central office and customer end (CO/CPE) signal filter unit 403 and output line filter unit 405. The device itself provides RJ-45, RJ-11 and other input and output interfaces through the communication port connection unit 407, and includes The automatic switching unit 409 that executes the automatic connection program, and the communication port controller 415 that is in charge of network detection. It can also optionally include a central office-automatic detection-client end (CO/AUTO/CPE) switching switch 411 for hardware function switching, and a status display unit 413 for displaying the working mode.

The network extension device disclosed in the present invention utilizes the data processing unit 401 to execute the signal exchange of each circuit unit, especially including generating a signal for switching the working mode of the automatic switching network extension device, processing the automatic switching signal and executing the communication between the central office and the user. The end (CO/CPE) circuit switching unit 403 switches the transmission circuit between the central office and the user end, including driving the status display unit 413 to display status lights or displaying the working status on the screen. The auto-switching signal, in particular through the communication port controller 415, detects the operating mode of another network extension device on the network.

The loop switching unit 403 at the central office and the user end is used for switching loops, which can be mainly implemented by switching circuits, or using a control chip to realize loop switching. The unit 403 mainly performs signal filtering through the output line filter unit 405. The output line filter unit 405 is electrically connected to the data processing unit 401, and is one of the main circuits in the present invention that can use a single device to perform the transmission function of the central office or the user end. According to the switch command generated by the central office and user end circuit switching unit 403, different filtering functions can be performed, especially realized by circuits or chips, to filter signals from the central office or user end network extension device.

The above-mentioned data processing unit 401 , the signal filtering unit 403 of the local end and the user end, and the output line filtering unit 405 form a control circuit, and in an embodiment, it can be realized by a single chip.

The output line filter unit 405 is also connected with a communication port connection unit 407 that provides RJ-45, RJ-11 and other input and output interfaces. When the data processing unit 401 generates a signal and controls the loop switching between the central station and the user terminal signal filtering unit 403 , the signal filtered by the output line filtering unit 405 will be transmitted to each communication port on the communication port connection unit 407 for output. In contrast, the input signal is also filtered and transmitted to the data processing unit 401 , and then output through looping, filtering and other processes.

The communication port connection unit 407 is connected to the above-mentioned telephone line port (RJ-11), so as to connect to the external network or the device located at the other end (opposite CO end or CPE end), and connect to the Ethernet port (RJ-45 ) to connect to the local area network. During the process of connecting to the network through various communication ports, the data transmitted by the communication port connection unit 407 will be transmitted or received through the output line filter unit 405 in the figure. The other end interface of this network extension device will be another network extension device corresponding to this device, where the local device is switched to the central office (CO end) network extension device, then the other end device should be the user end (CPE end) network extension device and vice versa. And the present invention realizes the connection with the other end device especially through an automatic connection program.

In particular, in the present invention, an automatic switching unit 409 that executes an automatic connection program is arranged in the device. This automatic switching unit 409 can be preset as an automatic switching mode, or according to the local end-automatic detection of the electrical connection in the figure - The user end (CO/AUTO/CPE) switching switch 411 is switched to generate a signal to determine whether to execute the automatic connection procedure. According to the embodiment of the present invention, the local end-automatic detection-user end switching switch 411 is an optional circuit, which provides the functions of manual setting and switching to automatic setting, and the automatic switching unit 409 receives the automatic switching generated by the switching switch 411 signal to perform automatic connection, or, the switch 411 is manually switched to the local end mode or the user end mode, and the generated signal is directly transmitted to the data processing unit 401, and the data processing unit 401 controls the circuits 403, 405 to execute the corresponding Loop switching and filtering.

The present invention is also specially provided with a communication port controller 415 responsible for network detection, which is electrically connected to the automatic switching unit 409 and the data processing unit 401 . According to the automatic connection program, the data processing unit 401 detects whether there is another network extension device on the network through the communication port controller 415, and tries to connect according to the setting parameters generated by the automatic switching unit 409. Whether the connection is successful or not, relevant information will be fed back to Automatic switching unit 409 .

There is also a status display unit 413 for displaying the working mode, which is electrically connected to the data processing unit 401, extracts the information therein, and displays the operating status of the device with multiple lights, including the circuit selected after switching (CO terminal or CPE terminal), The current connection status, the normal operation or error of the overall device, the power supply status, etc., can be implemented by using the on and off or color changes of multiple LED lights, or by using the display screen to let the user know the switchable VDSL office. The operation of the network extension device of the end-to-end loop.

For the automatic connection program provided by the automatic switching network extension device of the present invention, one of the flow charts of the automatic connection program of the present invention is shown in FIG. 5 .

The installation environment of the automatic switching network extension device can refer to Figure 2. It is mainly connected to the telephone line port of the network extension device at the other end through the telephone line port, and the device provides another or more network line parts, which are mainly used to connect to a Ethernet, usually a local area network or a device that supports Ethernet.

When the automatic switching network extension device starts (step S501), the internal circuit will perform an initialization setting (step S503), which mainly drives the internal circuit components and activates the communication ports, and generates a group of connections through the automatic switching unit 409 Parameters include the setting parameters required by the communication protocol and the setting code for setting the working mode (step S505). The setting code determines whether the device operates in the local end working mode or the user end working mode, and controls the loop switching. Afterwards, the communication port controller 415 sends data packets through the network through the communication port, and detects whether one end has a network extension device that has been activated, and checks its working mode. In an embodiment, the network extension device to be connected at the other end will also send a data packet, and the communication port controller 415 detects its working mode through the received data packet, and as in step S507, according to the detection result, the automatic connection program judges that the connection is automatic. Is it possible to connect the switching network extension device with another network extension device?

If the connection has not yet been realized, then step S505 continues to generate connection parameters, including setting the working mode according to the generated setting code, and continues to judge whether the connection can be realized. If as in step S509, the connection can be realized after the parameters are matched.

In the automatic connection procedure, the above step S505 to step S507 will be repeated until the connection is realized. After the connection, the connection status may still be checked regularly, and the automatic connection procedure will be executed if necessary. For the embodiment, please refer to the flowchart shown in FIG. 6 .

When the connection parameters are generated in step S505, which includes a setting code, the setting code can be generated automatically, and there are many ways to generate it. One embodiment is generated by the above-mentioned switch, and the setting code is manually generated, or switched When AUTO, it will be generated automatically. The second embodiment is to sequentially generate the values of 0 and 1, so as to control the device to work in the local mode or the client mode. The third embodiment is a setting code (step S601) generated by a random number generator (not shown, which can be generated by a data processing unit), the setting code is the value generated by the random number generator, and this value may be an odd number As for the even number, the present invention sets the relative working mode according to the odd number or the even number.

In this example, step S603 judges whether the number is an odd number? If it is an odd number, then as in step S605, the automatic switching unit 409 generates a setting signal and transmits it to the data processing unit 401, thereby setting the control circuit as the local end mode; if it is not an odd number, it is an even number, then as in step S607, the data processing unit Step 401 is to set the control circuit in the client mode according to the setting signal. Odd and even settings can be swapped.

When it is set as the central office or the client, the step goes to S507 to execute automatic connection to determine whether to connect with another network extension device. Since the network extension devices at both ends need to be connected by master-slave matching, one end needs to be an active (master) local end device, and the other end needs to be a slave (slave) user end device.

In this step S507, according to the setting code, set the central office mode or the client mode, and at the same time transmit the connection parameters required for the handshaking procedure (handshaking) of the two network extension devices, if the other end is the same work Mode, the steps need to repeat the above S601 using random numbers to set the working mode, and continue to step S605 or S607; if the other end is set to a different working mode, then connect by passing the connection parameters, that is, enter the steps described in Figure 5 S509, the connection can be realized after each parameter is matched.

To sum up, the main feature of the automatic switching network extension device disclosed in the present invention is to use an automatic connection program to connect with the remote device by automatically setting the central office or user end network extension device, so that the device can The labor-saving and convenient connection method is applied to the laid telephone lines for network connection, and can easily expand more than two regional networks.

The above descriptions are only preferred feasible embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, all equivalent structural changes made by using the description of the present invention and the contents of the accompanying drawings are all included in the scope of the present invention in the same way. within the scope of protection.

Claims (9)

1. A switching method of an automatic switching type network extension device, characterized in that the method comprises steps: (a) initializing an automatic switching network extension device; (b) generating a set of connection parameters, which includes a setting code for setting the working mode, wherein the setting code is a setting code generated by random numbers; (c) automatically set a working mode according to the setting code, which is a central office working mode or a user terminal working mode; (d) detecting the working mode of another network extension device to be connected; (e) According to the detection result, it is judged whether the working mode of the automatic switching network extension device and the other network extension device can be connected; (f) if it cannot be connected, repeat steps (b) to (e); and (g) If connection is possible, the connection is realized through a handshake procedure. 2. The switching method of the automatic switchable network extension device according to claim 1, characterized in that, according to whether the setting code is odd or even, the automatic switchable network extension device is set to operate in the central working mode or The working mode of the client. 3. The switching method of the automatic switching network extension device according to claim 1, characterized in that the automatic switching network extension device judges its working mode through the data packet sent by the network extension device at the other end, and the other end The working mode of a network extension device is different from that of the automatic switching network extension device, and the connection can only be realized. 4. An automatic switching network extension device, characterized in that the device includes: An automatic switching unit is used to generate a set value using random numbers, set the automatic switching network extension device to operate in a local end working mode or a client working mode according to the set value, and execute an automatic connection procedure, If it cannot be connected, automatically continue to use random numbers to generate another set value, set the working mode according to the another set value, and repeat the automatic connection procedure until the connection is realized; A communication port connection unit has a plurality of communication ports, so as to connect another network extension device with a network; An integrated signal processing unit, electrically connected to the automatic switching unit and the communication port connection unit, used to execute the signal exchange between each circuit unit in the automatic switching network extension device, and according to the station set by the automatic switching unit The terminal working mode or the client working mode executes data processing with the other network extension device; A communication port controller is electrically connected to the integrated signal processing unit and the automatic switching unit for detecting the working mode of the other network extension device. 5. The automatic switching network extension device as claimed in claim 4, further comprising a status display unit for displaying the working mode of the automatic switching network extension device. 6 . The automatic switching network extension device according to claim 4 , further comprising a central office-automatic detection-client switching switch for switching hardware functions. 7 . 7. The automatic switching network extension device according to claim 4, characterized in that the automatic switching network extension device further comprises a panel, the panel includes: A selection switch, with three options of local end, user end and automatic detection; at least one Ethernet port to connect to the network; a telephone line port through which the other network extension device is connected; and A status indicator light is used to display the working mode of the automatic switching network extension device. 8. An automatic switching network extension device, characterized in that the device includes: A data processing unit, which executes the signal exchange of each circuit unit in the automatic switching network extension device, and generates a signal for switching the automatic switching network extension device to switch the working mode of the local end or the user end; A central office and user end signal filtering unit is electrically connected to the data processing unit, and switches the transmission circuit between the central office and the user end according to the signal generated by the data processing unit; An output line filter unit, electrically connected to the central office and the user end signal filter unit, and performs signal filtering according to a switching command generated by the central office and user end signal filter unit; A communication port connection unit, electrically connected to the output line filter unit, has a plurality of communication ports, so as to connect another network extension device and a network; An automatic switching unit, electrically connected to the data processing unit, used to generate a set value using a random number, and set the automatic switching network extension device to operate as the local end or the user end work mode according to the set value, Execute an automatic connection procedure, if the connection cannot be made, automatically continue to use random numbers to generate another set value, set the working mode according to the another set value, and repeat the automatic connection procedure until the connection is realized; A communication port controller, electrically connected to the data processing unit and the automatic switching unit, for detecting the working mode of another network extension device, and feeding back to the communication port controller; A central office-automatic detection-client switching switch for realizing hardware function switching; and A status display unit for displaying the working mode of the automatic switching network extension device. 9. The automatic switching network extension device according to claim 8, characterized in that the automatic switching network extension device comprises a panel, and the panel includes: A selection switch, with three options of local end, user end and automatic detection; At least one Ethernet port, using an RJ-45 communication port to connect to the network; A telephone line port, using a communication port of RJ-11 specification, so as to connect the other network extension device; and A status indicator light is used to display the working mode of the automatic switching network extension device.