CN103905579B - Communication method, communication system, platform and related equipment between platform and terminal - Google Patents

Abstract

The invention discloses a communication method between a platform and a terminal, which comprises the following steps: a Network Address Translation (NAT) device receives a communication request from a platform, wherein the communication request carries a terminal private network IP address and a terminal number; and the NAT equipment forwards the communication request to a terminal corresponding to the terminal private network IP address or the terminal number, and then the terminal establishes a communication link with the platform and interacts a message based on the communication link. The invention also correspondingly discloses a communication system, a platform and related equipment. By adopting the scheme of the invention, even if the terminal is in a private network, the platform can actively communicate with the terminal after the connection between the platform and the terminal is disconnected, thereby improving the communication efficiency.

Description

Communication method between platform and terminal, communication system, platform and related equipment

technical field

The invention relates to the field of data communication, in particular to a communication method between a platform and a terminal, a communication system, a platform and related equipment.

Background technique

At present, the communication mechanism between the platform and the terminal mainly includes:

1) The terminal actively communicates with the platform. Specifically, the platform IP address and communication port are generally preset or configured in the terminal, or the platform communication URL/DNS address is preset or configured. The terminal IP address is carried in the interactive message, and the platform responds to the message initiated by the terminal according to the terminal IP address. Under this mechanism, the terminal sends a heartbeat packet to the platform as needed to notify the platform that the terminal is online, thereby maintaining a long connection with the platform. Based on this long connection, the terminal can actively communicate with the platform, and the platform can also actively communicate with the terminal. As a server, the platform needs to monitor the requests initiated by the terminal on the communication port. When a request from the terminal arrives at the platform, the platform immediately processes and interacts with it.

2) The platform actively communicates with the terminal. Specifically, the platform actively initiates a request to the terminal according to the IP address of the terminal, or, when the terminal has the ability to send and receive short messages, the platform sends a data connection pull-up message to the terminal, and the terminal establishes a data connection after receiving the pull-up message, and actively Initiate a communication request with the platform and exchange messages. Under this mechanism, the terminal, as the server, needs to monitor the request initiated by the platform on the communication port. When the platform has a request to the terminal, the terminal immediately processes and interacts. In order to reduce the complexity of terminal processing, it can be required that when the platform actively communicates with the terminal, the message sent is a fixed message message, and the terminal sends a message exchange request message after receiving the message; or, the platform can also send user data Packet protocol (User Datagram Protocol, UDP) message, requiring the terminal to initiate a connection request.

However, for the above-mentioned communication mechanism, if the long connection between the terminal and the platform is disconnected due to an abnormal situation, then, because the terminal cannot recognize the abnormal situation, it cannot restore the connection with the platform in time, which will affect the communication efficiency; in addition, if the terminal If the IP address of the terminal is a private network address, and the terminal does not have the function of SMS communication, after the connection between the platform and the terminal is disconnected, the platform will not be able to find the terminal and thus cannot communicate.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a communication method, communication system, platform and related equipment between the platform and the terminal. After the connection between the platform and the terminal whose IP address is a private network address is disconnected, the platform can find the terminal And communicate with it, so as to improve communication efficiency.

In order to achieve the above object, technical solution of the present invention is achieved in that way:

A communication method between a platform and a terminal, comprising:

The network address translation NAT device receives a communication request from the platform, and the communication request carries the terminal private network IP address and the terminal number;

The NAT device forwards the communication request to the terminal corresponding to the private network IP address of the terminal or the terminal number, and then, the terminal establishes a communication link with the platform, and reports an interactive message based on the communication link arts.

The NAT device forwards the communication request to the terminal corresponding to the private IP address of the terminal or the terminal number as:

When the IP address distribution method of the NAT device is static distribution, the communication request is forwarded to the port corresponding to the private network IP address; when the IP address distribution method of the NAT device is dynamic distribution, on each port sending a broadcast message carrying the terminal number, and then forwarding the communication request to the port that responds to the broadcast message.

The method also includes:

After the platform and the terminal exchange message messages, the terminal sends a heartbeat packet to the platform regularly, keeps the communication link connected, and regularly polls to detect the network connection status. When an abnormal disconnection is detected, initiate and A communication link with the platform is established.

When the terminal detects one or more of the following, it is determined to be abnormally disconnected from the network:

The upper-layer application cannot communicate with the platform without completing a complete message response during message communication;

If there is a dial-up program running and the program is not disconnected normally, the IP layer has detected that the network is disconnected;

The disconnection of the network port is not detected, but the IP layer is no longer connected.

A communication method between a platform and a terminal, comprising:

When the platform needs to communicate with a terminal in the private network, obtain the public network address, the terminal private network IP address and the terminal number when the terminal established a connection last time;

The platform sends a communication request to the corresponding NAT device according to the public network address to establish a communication link with the terminal, and the communication request carries the private network IP address of the terminal and the terminal number.

A kind of NAT equipment, comprises: receiving module and sending module; Wherein,

The receiving module is configured to receive a communication request from the platform, and the communication request carries a terminal private network IP address and a terminal number;

The sending module is configured to forward the received communication request to the terminal corresponding to the private network IP address of the terminal or the terminal number, so that the terminal can establish a communication link with the platform, based on the communication link exchange message packets.

The NAT device also includes an IP address allocation mode determination module,

The IP address allocation mode determination module is used to determine the IP address allocation mode of the NAT device according to the configuration of the NAT device;

The sending module is specifically configured to forward the communication request to the port corresponding to the private network IP address when the IP address allocation mode determination module determines that the IP address allocation mode of the NAT device is static allocation; When the IP address allocation mode determining module determines that the IP address allocation mode of the NAT device is dynamic allocation, a broadcast message carrying the terminal number is sent on each port, and then the communication request is forwarded to the broadcast message The port on which the message is answered.

A terminal, including: a receiving module, a matching module and a sending module; wherein,

The receiving module is configured to receive a communication request forwarded by the NAT device and a broadcast message sent by the NAT device, the broadcast message carrying a terminal number;

The matching module is configured to, after the receiving module receives the broadcast message, match the terminal number carried in the broadcast message with the terminal number of the terminal to which it belongs;

The sending module is configured to return a response message when the matching module succeeds in matching.

The terminal also includes: a detection module and a connection establishment module; wherein,

The detection module is used to regularly poll and detect the network connection status when the message message exchange between the platform and the terminal ends, but the communication link is kept connected;

The connection establishment module is configured to initiate and establish a communication link with the platform when the detection module detects an abnormal network disconnection.

The detection module is specifically used to determine that the network is abnormally disconnected when one or more of the following is detected:

The upper-layer application cannot communicate with the platform without completing a complete message response during message communication;

If there is a dial-up program running and the program is not disconnected normally, the IP layer has detected that the network is disconnected;

The disconnection of the network port is not detected, but the IP layer is no longer connected.

A communication system, including a platform, a NAT device and a terminal, wherein,

The platform is used to obtain the public network address, the terminal private network IP address and the terminal number when the terminal established a connection last time when it needs to communicate with the terminal in the private network; after that, according to the public network address Sending a communication request to the corresponding NAT device to establish a communication link with the terminal, the communication request carrying the private IP address of the terminal and the terminal number;

The NAT device is configured to forward the communication request to the terminal corresponding to the private network IP address of the terminal or the terminal number, so that the terminal can establish a communication link with the platform, and interact based on the communication link message message;

The terminal is configured to receive the communication request forwarded by the NAT device and the broadcast message sent by the NAT device; and after receiving the broadcast message, match the terminal number carried in the broadcast message with its own terminal number, and when the match is successful, Return a reply message.

The NAT device is specifically used to forward the communication request from the platform to the port corresponding to the private network IP address when the IP address allocation method is static allocation, and to establish a connection between the platform and the private network IP address. The communication link of the terminal; when the IP address allocation mode is dynamic allocation, a broadcast message carrying the terminal number is sent on each port, and then the communication request from the platform is forwarded to the port that responds to the broadcast message, A communication link between the platform and the terminal corresponding to the terminal number is established.

The terminal is further configured to regularly send a heartbeat packet to the platform after the exchange message message between the platform and the terminal ends, to keep the communication link connected, and to regularly poll to detect the network connection status, and to detect an abnormal disconnection. network, initiate and establish a communication link with the platform,

When the terminal detects one or more of the following, it is determined to be abnormally disconnected from the network:

The upper-layer application cannot communicate with the platform without completing a complete message response during message communication;

If there is a dial-up program running and the program is not disconnected normally, the IP layer has detected that the network is disconnected;

The disconnection of the network port is not detected, but the IP layer is no longer connected.

The communication method, communication system, platform and related equipment between the platform and the terminal of the present invention, the network address translation (NAT) equipment receives the communication request from the platform, and the communication request carries the terminal private network IP address and the terminal number; the NAT equipment The communication request is forwarded to the terminal corresponding to the private IP address of the terminal or the terminal number, and then the terminal establishes a communication link with the platform, and exchanges message messages based on the communication link. With the solution of the present invention, even if the terminal is in the private network, the platform can actively communicate with the terminal after the connection between the platform and the terminal is disconnected, thereby improving communication efficiency; in addition, the long connection between the terminal and the platform is due to After the abnormal situation is disconnected, the terminal can identify various abnormal situations and restore the connection with the platform in time, thereby further improving communication efficiency.

Description of drawings

1 is a schematic flow diagram of a communication method between a platform and a terminal according to an embodiment of the present invention;

FIG. 2 is a schematic flowchart of another communication method between a platform and a terminal according to an embodiment of the present invention;

3 is a schematic structural diagram of a NAT device according to an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a terminal according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of another terminal according to an embodiment of the present invention;

FIG. 6 is a schematic structural diagram of a communication system according to an embodiment of the present invention;

7 is a schematic flowchart of a communication method between a platform and a terminal according to Embodiment 1 of the present invention;

FIG. 8 is a schematic flowchart of a communication method between a platform and a terminal according to Embodiment 2 of the present invention;

FIG. 9 is a schematic flowchart of a communication method between a platform and a terminal according to Embodiment 3 of the present invention.

detailed description

The basic idea of the present invention is: the NAT device receives the communication request from the platform, and the communication request carries the terminal private network IP address and the terminal number; the NAT device forwards the communication request to the terminal private network IP address or the terminal Afterwards, the terminal establishes a communication link with the platform, and exchanges message messages based on the communication link.

Fig. 1 is a schematic flow chart of a communication method between a platform and a terminal according to an embodiment of the present invention. As shown in Fig. 1, the method includes:

Step 101: the NAT device receives a communication request from the platform, and the communication request carries the terminal private network IP address and the terminal number;

Step 102: The NAT device forwards the communication request to the terminal corresponding to the private network IP address of the terminal or the terminal number, and then, the terminal establishes a communication link with the platform, based on the communication link Interactive messages.

Optionally, the NAT device forwarding the communication request to the terminal corresponding to the private network IP address of the terminal or the terminal number is: when the IP address allocation mode of the NAT device is static allocation, forwarding the communication request to the port corresponding to the private network IP address; when the IP address allocation method of the NAT device is dynamic allocation, a broadcast message carrying the terminal number is sent on each port, and then the communication request is forwarded to the corresponding on the port on which the above broadcast message is answered.

Optionally, the method also includes:

After the platform and the terminal exchange message messages, the terminal sends a heartbeat packet to the platform regularly, keeps the communication link connected, and regularly polls to detect the network connection status. When an abnormal disconnection is detected, initiate and A communication link with the platform is established.

Optionally, when the terminal detects one or more of the following items, it is determined to be abnormally disconnected from the network:

The upper-layer application cannot communicate with the platform without completing a complete message response during message communication;

If there is a dial-up program running and the program is not disconnected normally, the IP layer has detected that the network is disconnected;

The disconnection of the network port is not detected, but the IP layer is no longer connected.

It should be noted that the above-mentioned method for the terminal to detect abnormal network disconnection is not limited to the scenario of maintaining a long connection after establishing a connection and exchanging message messages according to steps 101 and 102, but can also be applied separately to establishing a connection and exchanging message messages in other ways. The scene of maintaining a long connection is described later in this article, so as to restore the connection between the terminal and the platform in time. For example, a certain service function requires the terminal to actively communicate with the platform. After the connection between the platforms is disconnected, the platform actively communicates according to the IP address of the terminal obtained last time. If the communication between the platform and the IP address of the terminal obtained last time fails, the communication method described in steps 101 and 102 is used to communicate with the terminal. communication of the terminal.

The embodiment of the present invention also correspondingly proposes a communication method between the platform and the terminal, as shown in FIG. 2 , the method includes:

Step 201: When the platform needs to communicate with a terminal in the private network, obtain the public network address, the terminal private network IP address and the terminal number when the terminal established a connection last time;

Step 202: The platform sends a communication request to the corresponding NAT device according to the public network address to establish a communication link with the terminal, and the communication request carries the terminal's private network IP address and terminal number.

The embodiment of the present invention also correspondingly proposes a NAT device, the NAT device includes: a receiving module 31 and a sending module 32; wherein,

The receiving module 31 is configured to receive a communication request from the platform, the communication request carrying the terminal private network IP address and the terminal number;

The sending module 32 is configured to forward the received communication request to the terminal corresponding to the private network IP address of the terminal or the terminal number, so that the terminal can establish a communication link with the platform, based on the communication link Interactive messages.

Optionally, as shown in Figure 3, the NAT device also includes an IP address allocation mode determination module 33,

The IP address assignment method determination module 33 is used to determine the IP address assignment method of the NAT device according to the NAT device configuration;

The sending module 32 is specifically configured to forward the communication request to the port corresponding to the private network IP address when the IP address allocation mode determining module 33 determines that the IP address allocation mode of the NAT device is static allocation; When the IP address allocation mode determining module 33 determines that the IP address allocation mode of the NAT device is dynamic allocation, a broadcast message carrying the terminal number is sent on each port, and then the communication request is forwarded to the The port on which broadcast messages are answered.

The embodiment of the present invention also correspondingly proposes a terminal, as shown in FIG. 4 , the terminal includes: a receiving module 41, a matching module 42, and a sending module 43; wherein,

The receiving module 41 is configured to receive a communication request forwarded by the NAT device and a broadcast message sent by the NAT device, the broadcast message carrying a terminal number;

The matching module 42 is configured to match the terminal number carried in the broadcast message with the terminal number of the terminal to which it belongs after the receiving module 41 receives the broadcast message;

The sending module 43 is configured to return a response message when the matching module 42 matches successfully.

Optionally, as shown in FIG. 5, the terminal further includes: a detection module 51 and a connection establishment module 52; wherein,

The detection module 51 is used to periodically poll and detect the network connection status when the platform and the terminal exchange message message ends, but keep the communication link connected;

The connection establishment module 52 is configured to initiate and establish a communication link with the platform when the detection module 51 detects an abnormal network disconnection.

Optionally, the detection module 51 is specifically configured to determine that the network is abnormally disconnected when one or more of the following is detected:

The upper-layer application cannot communicate with the platform without completing a complete message response during message communication;

If there is a dial-up program running and the program is not disconnected normally, the IP layer has detected that the network is disconnected;

The disconnection of the network port is not detected, but the IP layer is no longer connected.

It should be noted that the terminal can be physically integrated with the NAT device and support NAT device functions, including port mapping, IP address mapping and other functions.

The embodiment of the present invention also correspondingly proposes a communication system, as shown in FIG. 6 , the communication system includes a platform 61, a NAT device 62 and a terminal 63, wherein,

The platform 61 is used to obtain the public network address, the private network IP address of the terminal and the terminal number when the terminal established a connection last time when it is necessary to communicate with the terminal in the private network; The corresponding NAT device sends a communication request to establish a communication link with the terminal, and the communication request carries the private IP address of the terminal and the terminal number;

The NAT device 62 is configured to forward the communication request to the terminal corresponding to the private network IP address of the terminal or the terminal number, so that the terminal can establish a communication link with the platform, and exchange messages based on the communication link message;

The terminal 63 is used to receive the communication request forwarded by the NAT device and the broadcast message sent by the NAT device; and after receiving the broadcast message, match the terminal number carried by the broadcast message with its own terminal number, and when the match is successful, return Answer message.

Optionally, the NAT device 62 is specifically used to forward the communication request from the platform 61 to the port corresponding to the private network IP address when the IP address allocation method is static allocation, and to establish the connection between the platform 61 and the private network IP address. The communication link of the terminal corresponding to the address; when the IP address allocation mode is dynamic allocation, a broadcast message carrying the terminal number is sent on each port, and then the communication request from the platform 61 is forwarded to respond to the broadcast message A communication link between the platform 61 and the terminal corresponding to the terminal number is established on the port.

Optionally, the terminal 63 is also used to regularly send a heartbeat packet to the platform after the interactive message message between the platform and the terminal ends, keep the communication link connected, and regularly poll to detect the network connection status, detect When the network is abnormally disconnected, initiate and establish a communication link with the platform,

Optionally, when the terminal 63 detects one or more of the following, it is determined to be abnormally disconnected from the network:

The upper-layer application cannot communicate with the platform without completing a complete message response during message communication;

If there is a dial-up program running and the program is not disconnected normally, the IP layer has detected that the network is disconnected;

The disconnection of the network port is not detected, but the IP layer is no longer connected.

The technical solution of the present invention will be further described in detail through specific examples below.

Example 1

In this embodiment, the terminal initiates a connection request, the platform verifies and authenticates the terminal, and establishes a long connection with the terminal. After the long connection is established, it detects whether the network is disconnected abnormally. If there is an abnormal disconnection, it will be re-established immediately connect.

As shown in FIG. 7, the flow of the communication method between the platform and the terminal described in this embodiment specifically includes:

Step 701: The terminal initiates a connection to the platform, establishes a TCP/IP connection, and the platform obtains the terminal IP address.

Step 702: After establishing a connection with the platform, the terminal obtains a temporary Token.

In this connection, each time the subsequent terminal interacts with the platform, it needs to carry this temporary token, which is used as the authentication field for this communication connection and message message interaction.

Specifically, the platform binds the temporary Token with the IP address and port carried by the TCP/IP connection initiated by the terminal. When the connection is disconnected, the temporary Token also expires.

The temporary token is calculated by the platform according to a certain algorithm based on the terminal number reported by the terminal (pre-stored on the platform, or a logical number bound to the terminal number), IP address, port, and platform-generated random number. Using Token can ensure the security of long connection communication.

Step 703: The terminal and the platform exchange message messages to complete relevant logical operations.

Step 704: The message interaction ends. The platform does not disconnect the TCP/IP connection, and maintains the session connection, and the terminal does not actively disconnect the TCP/IP connection.

Step 705: The terminal regularly sends heartbeat packets to the platform, and the platform receives the heartbeat packets regularly to maintain the connection.

Step 706: The terminal detects whether the network is abnormally disconnected. If there is an abnormality, the terminal disconnects the TCP/IP connection with the platform, and the terminal needs to actively initiate a connection request to the platform, and the platform and the terminal re-establish a connection.

Here, after the detection process is started, the terminal may regularly poll and detect the network connection status under the PPP connection or IP connection. Specifically, it can be determined as an abnormal disconnection according to the following situations:

The upper-layer application cannot communicate with the platform without completing a complete message response during message communication;

If there is a dial-up program running and the program is not disconnected normally, the IP layer has detected that the network is disconnected;

The disconnection of the network port is not detected, but the IP layer is no longer connected.

It should be noted that the terminal detects the network status and the connection program after the network is disconnected is an operating system-level process. After the operating system is started, it starts together and cannot be suspended, closed or modified. In addition, when the TCP/IP connection between the terminal and the platform is disconnected , the platform can immediately detect that the TCP connection has been disconnected, and the platform releases the established TCP/IP connection and the session established by the application layer.

After the connection is re-established, the platform can send interactive messages to the terminal at any time for various operations and configurations.

Example 2

This embodiment describes a process in which the terminal is in a private network and the private network address remains unchanged, the TCP/IP connection between the platform and the terminal is disconnected, and the platform actively connects to the terminal for communication.

FIG. 8 is a schematic flow diagram of a communication method between a platform and a terminal in Embodiment 2 of the present invention. As shown in FIG. 8, the flow specifically includes:

Step 801: When the terminal actively initiates communication with the platform, it sends a message packet carrying the private network IP address of the terminal and the number permanently assigned to the terminal by the NAT device.

Step 802: After the terminal disconnects from the platform, the platform unlocks the NAT traversal message sent by the terminal when establishing a TCP/IP connection last time, and obtains the terminal's private network IP address and terminal number.

Here, the NAT traversal message is a message that has nothing to do with business logic, and is sent before business message interaction.

Step 803: The platform sends a communication request to the NAT device (corresponding to the public network address), and the communication request carries the private network IP address of the terminal and the terminal number.

Step 804: The statically allocated NAT device receives the communication request sent by the platform, and forwards the message sent to the public network address to the port bound to the private network address, thereby establishing a communication link between the platform and the terminal, and interacting information.

Example 3

This embodiment describes a process in which the terminal is in a private network and the private network address changes, the TCP/IP connection between the platform and the terminal is disconnected, and the platform actively connects to the terminal for communication.

FIG. 9 is a schematic flowchart of a communication method between a platform and a terminal in Embodiment 3 of the present invention. As shown in FIG. 9, the process specifically includes:

Step 901: When the terminal actively initiates communication with the platform, it sends a message packet carrying the private network IP address of the terminal and the number permanently assigned to the terminal by the NAT device.

Step 902: After the terminal disconnects from the platform, the platform unlocks the NAT traversal message sent by the terminal when establishing a TCP/IP connection last time, and obtains the terminal's private network IP address and terminal number.

Here, the NAT traversal message is a message that has nothing to do with business logic, and is sent before business message interaction.

Step 903: The platform sends a communication request to the NAT device (corresponding to the public network address), and the communication request carries the private network IP address of the terminal and the terminal number.

Step 904: After receiving the communication request sent by the platform, the NAT device whose allocation mode is dynamic allocation sends a broadcast message on each port. The broadcast message carries at least the terminal number. When a terminal receives this broadcast message, it matches its own terminal Number, if the terminal that matches the terminal number (it can carry the Token carried before disconnection for authentication verification) responds to the broadcast message, the NAT device forwards the message sent by the platform to this port according to the port of the response, and the terminal responds to the message sent by the platform The message message is used to respond, and the platform establishes a communication link with the terminal according to the response.

Specifically, the communication request sent by the platform can also carry one or more of the following information: notify the terminal of this number to establish a connection with the platform, message type (such as a connection message), and the platform IP address. Token, after the connection is re-established, a new Token will be carried.

The broadcast message forwarded by the NAT device notifies the platform of the numbered terminal to establish a connection with the platform, and the message includes the terminal number.

For the case where the IP address of the terminal is the IP address of the public network, if the terminal IP address does not change, the platform only needs to remember the IP address of the terminal for each communication, and can actively connect and communicate with the terminal; if the terminal IP address changes ( That is, the IP address obtained by the terminal every time it initiates a PPP connection changes), as long as the PPP connection is not disconnected this time, the platform can find the terminal according to the IP address assigned by the terminal this time, if the PPP connection is disconnected, the terminal will re-initiate PPP Connection request, to establish a new connection with the platform. If you want the PPP connection not to be disconnected, you can maintain a long connection between the terminal and the platform, thereby maintaining the PPP connection.

The solution described in the present invention can be applied to services that require the platform to actively communicate with the terminal (such as smart home, terminal remote management, etc.). Through the present invention, after the terminal interacts with the platform, it maintains a long connection. If the long connection is disconnected , the terminal performs various abnormal processing to initiate a connection; if the terminal fails to diagnose the abnormality, the connection between the terminal and the platform has been disconnected, and the platform can actively establish a communication connection with the terminal and exchange messages. Therefore, even if the platform and the terminal are not in the same network During the period, the platform can still actively find the terminal, send various messages to the terminal, and perform various operations and configurations.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention.

Claims (11)

1. A method for communication between a platform and a terminal, the method comprising:

the NAT equipment receives a communication request from a platform, wherein the communication request carries a terminal private network IP address and a terminal number, and the communication request also carries one or more of the following items of information: informing a terminal with a terminal number to establish connection, a message type and a platform IP address with a platform;

the NAT equipment forwards the communication request to a terminal corresponding to the terminal private network IP address or the terminal number, and then the terminal establishes a communication link with the platform and interacts a message based on the communication link;

after the platform and the terminal exchange message messages, the terminal sends heartbeat packets to the platform at regular time, keeps the communication link connected, polls the network connection state at regular time, and initiates and establishes a communication link with the platform when detecting abnormal network disconnection.

2. The method of claim 1, wherein the forwarding of the communication request to the terminal corresponding to the terminal private network IP address or the terminal number by the NAT device is:

when the IP address allocation mode of the NAT equipment is static allocation, the communication request is forwarded to a port corresponding to the private network IP address; and when the IP address allocation mode of the NAT equipment is dynamic allocation, sending a broadcast message carrying the terminal number on each port, and then forwarding the communication request to a port responding to the broadcast message.

3. The method according to claim 1, wherein the terminal determines an abnormal network outage when detecting one or more of the following:

the upper layer is applied to message communication, does not complete message response and cannot communicate with the platform;

if the dialing program runs and the program is not normally disconnected, the IP layer detects the network disconnection;

the disconnection of the network port is not detected, but the IP layer can not be connected.

4. A method for communication between a platform and a terminal, the method comprising:

when a platform needs to communicate with a terminal in a private network, acquiring a public network address, a terminal private network IP address and a terminal number when the terminal establishes connection last time;

the platform sends a communication request to corresponding NAT equipment according to the public network address, and establishes a communication link with the terminal, wherein the communication request carries the terminal private network IP address and the terminal number, and the communication request also carries one or more of the following information: informing a terminal with a terminal number to establish connection, a message type and a platform IP address with a platform;

after the platform and the terminal exchange message messages, the terminal sends heartbeat packets to the platform at regular time, keeps the communication link connected, polls the network connection state at regular time, and initiates and establishes a communication link with the platform when detecting abnormal network disconnection.

5. A NAT device, comprising: the device comprises a receiving module and a sending module; wherein,

the receiving module is used for receiving a communication request from a platform, wherein the communication request carries a terminal private network IP address and a terminal number, and the communication request also carries one or more of the following items of information: informing the numbered terminal to establish connection, message type and platform IP address with the platform;

the sending module is used for forwarding the received communication request to a terminal corresponding to the terminal private network IP address or the terminal number so as to establish a communication link between the terminal and the platform and exchange message messages based on the communication link;

after the platform and the terminal exchange message messages, the terminal sends heartbeat packets to the platform at regular time, keeps the communication link connected, polls the network connection state at regular time, and initiates and establishes a communication link with the platform when detecting abnormal network disconnection.

6. The NAT device of claim 5, wherein the NAT device further comprises an IP address assignment determination module,

the IP address allocation mode determining module is used for determining the IP address allocation mode of the NAT equipment according to the NAT equipment configuration;

the sending module is specifically configured to forward the communication request to a port corresponding to the private network IP address when the IP address allocation manner determining module determines that the IP address allocation manner of the NAT device is static allocation; and when the IP address allocation mode determining module determines that the IP address allocation mode of the NAT equipment is dynamic allocation, sending a broadcast message carrying the terminal number on each port, and then forwarding the communication request to a port responding to the broadcast message.

7. A terminal, characterized in that the terminal comprises: the device comprises a receiving module, a matching module and a sending module; wherein,

the receiving module is configured to receive a communication request forwarded by the NAT device and a broadcast message sent by the NAT device, where the broadcast message carries a terminal number, and the communication request carries one or more of the following information: informing a terminal with a terminal number to establish connection, a message type and a platform IP address with a platform;

the matching module is used for matching the terminal number carried by the broadcast message with the terminal number of the terminal to which the matching module belongs after the receiving module receives the broadcast message;

the sending module is used for returning a response message when the matching module is successfully matched;

wherein, this terminal station still includes: the device comprises a detection module and a connection establishing module; wherein,

the detection module is used for polling and detecting the network connection state at regular time when the platform and the terminal exchange message is finished but the communication link is kept connected;

and the connection establishing module is used for initiating and establishing a communication link with the platform when the detection module detects abnormal network disconnection.

8. The terminal according to claim 7, wherein the detecting module is specifically configured to determine that the network is abnormally disconnected when one or more of the following are detected:

the upper layer is applied to message communication, does not complete message response and cannot communicate with the platform;

if the dialing program runs and the program is not normally disconnected, the IP layer detects the network disconnection;

the disconnection of the network port is not detected, but the IP layer can not be connected.

9. A communication system comprising a platform, a NAT device and a terminal, wherein,

the platform is used for acquiring a public network address, a terminal private network IP address and a terminal number when the terminal establishes connection last time when the terminal needs to communicate with a terminal in a private network; then, a communication request is sent to the corresponding NAT equipment according to the public network address, a communication link with the terminal is established, the communication request carries the terminal private network IP address and the terminal number, and the communication request also carries one or more of the following information: informing a terminal with a terminal number to establish connection, a message type and a platform IP address with a platform;

the NAT equipment is used for forwarding the communication request to a terminal corresponding to the terminal private network IP address or the terminal number so that the terminal can establish a communication link with the platform and exchange message messages based on the communication link;

the terminal is used for receiving the communication request forwarded by the NAT equipment and the broadcast message sent by the NAT equipment; after receiving the broadcast message, matching the terminal number carried by the broadcast message with the terminal number of the broadcast message, and returning a response message when the matching is successful; and the system is also used for sending heartbeat packets to the platform at regular time after the platform and the terminal exchange message are finished, keeping the communication link connected, polling and detecting the network connection state at regular time, and initiating and establishing the communication link with the platform when abnormal network disconnection is detected.

10. The system of claim 9,

the NAT device is specifically used for forwarding a communication request from a platform to a port corresponding to the private network IP address when the IP address allocation mode is static allocation, and establishing a communication link between the platform and a terminal corresponding to the private network IP address; and when the IP address allocation mode is dynamic allocation, sending a broadcast message carrying the terminal number on each port, then forwarding a communication request from the platform to a port responding to the broadcast message, and establishing a communication link between the platform and the terminal corresponding to the terminal number.

11. The system of claim 9 or 10,

when the terminal detects one or more of the following conditions, the terminal determines that the network is abnormally disconnected:

the upper layer is applied to message communication, does not complete message response and cannot communicate with the platform;

if the dialing program runs and the program is not normally disconnected, the IP layer detects the network disconnection;

the disconnection of the network port is not detected, but the IP layer can not be connected.