RU2822609C9 - Method and apparatus for forwarding packets for heterogeneous network - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to communication technologies. Technical result is achieved by forwarding an interaction packet between a client and a server based on a user mode protocol stack, which includes receiving a request packet sent by the client, and sending the first response packet to the client in response to the request packet, adding the request packet to the first buffer queue and forwarding the request packet to the server so that the server sends the second response packet in response to the request packet, receiving a second response packet and sending an acknowledgment packet to the server based on the second response packet and adding the second response packet to the second buffer queue and sending the second response packet to the client.

EFFECT: high efficiency by forwarding packets at the transport level by a forwarding module.

9 cl, 6 dwg

Description

Field of technology

The present application relates to the field of communication technologies and, in particular, to a method and device for forwarding packets for a heterogeneous network.

State of the art

The network on the network server side is very stable and supports user requests with high multi-threading and high bandwidth. The wireless mobile network has its own data transmission characteristics, such as packet forwarding failure, inability to accurately and timely detect packet loss, and resource shortage during busy times. When the above situations occur, the user's Internet access speed changes rapidly, affecting the quality of mobile users' Internet access.

Proxy server technology in related fields of technology is mainly based on forward proxy server technology and reverse proxy server technology. Transmission Control Protocol (TCP) connections are respectively established between the proxy service and the two ends of the communication, that is, the proxy service must establish a TCP connection with both the access client and the server, and then interactively forward data at the session level. The forward proxy server technology is opaque to the client, and the reverse proxy server technology is opaque to the server.

The essence of the invention

The technical problem solved by the embodiments of the present application is to implement a transparent proxy service between a client and a server, and to solve the problem of the impact on forwarding performance due to multiple copies of data between the user mode and the kernel mode in the proxy service. The embodiments of the present application provide a method and device for forwarding packets for a heterogeneous network.

A packet forwarding method for a heterogeneous network according to embodiments of the present application includes the following: a connection request sent by a client is received; the connection request is forwarded to a server to establish a connection between the client and the server; an interaction packet is forwarded between the client and the server based on a user mode protocol stack.

According to the packet forwarding method for a heterogeneous network in the embodiments of the present application, by performing packet forwarding at the transport layer, it is possible to avoid the bottleneck problem in the proxy service performance caused by multiple copies of a packet in the user mode and the kernel mode during the forwarding process, thereby realizing zero-copy packet forwarding based on the user mode protocol stack and effectively improving the system performance. In addition, according to the packet forwarding method of the present application, there is no need to create a fictitious intermediary and there is no risk of an intermediary attack, and encryption by the Transport Layer Security (TLS) protocol, etc. is supported, which improves the security and reliability of packet forwarding.

According to some embodiments of the present application, the operation of establishing a connection between a client and a server includes the following: a request for establishing a connection sent by the client is received and forwarded to the server, after which the server sends a first response message to the client in response to the request for establishing a connection; the first response message is received and transmitted to the client, after which the client sends a second response message to the server in response to the first response message; and the second response message is received and transmitted to the server to establish a connection between the client and the server.

In some embodiments of the present application, the operation of receiving and forwarding to the server a connection request sent by a client includes the following: the connection request sent by the client is received in accordance with a specified default route; a session is created based on the connection request, and the connection request is forwarded to the server after updating the address of the connection request.

According to some embodiments of the present application, the contents of a session message include: a connection serial number and a window size.

In some embodiments of the present application, an operation of forwarding an interaction packet between a client and a server based on a user mode protocol stack includes the following: a request packet sent by a client is received, and a first response packet is sent to the client in response to the request packet; the request packet is added to a first buffer queue and sent to the server, after which the server sends a second response packet in response to the request packet; the second response packet is received, and an acknowledgement (ACK) packet is sent to the server based on the second response packet; the second response packet is added to a second buffer queue and sent to the client.

According to some embodiments of the present application, the method further comprises the following: if the data capacity of the second response packet in the second buffer queue is greater than a threshold value, the window size of the request packet sent to the server is reduced to reduce the rate at which the server sends packets.

In some embodiments of the present application, the method further comprises the following: if the client does not receive the second response packet within a predetermined period of time, the second response packet is again added to the second buffer queue and sent to the client.

According to some embodiments of the present application, the method further comprises the following: if a packet loss is detected during the packet interaction process, the packet interaction window size is adjusted to a specified threshold value.

Embodiments of the present application also provide a packet forwarding device for a heterogeneous network that includes a forwarding module.

The forwarding module is configured to forward the connection request and response message between the client and the server, establish the connection between the client and the server, and forward the communication packet between the client and the server based on the user mode protocol stack.

According to the packet forwarding device for a heterogeneous network in the embodiments of the present application, by performing packet forwarding at the transport layer by the forwarding module, it is possible to avoid the bottleneck problem in the proxy service performance caused by multiple copies of a packet in the user mode and kernel mode during forwarding, thereby realizing zero-copy packet forwarding based on the user mode protocol stack and effectively improving the system performance. In addition, according to the packet forwarding device of the present application, there is no need to create a dummy intermediary and there is no risk of a man-in-the-middle attack, and TLS encryption etc. are supported, which improves the security and reliability of packet forwarding.

The embodiments of the present application also provide a machine-readable storage medium in which a program for performing the transmission of information is stored. The program, executed by the processor, performs the operations of the above-described method for forwarding packets for a heterogeneous network.

According to the machine-readable medium in the embodiments of the present application, by implementing the packet forwarding method for a heterogeneous network, the packet forwarding can be performed at the transport layer of the proxy node, and the bottleneck problem in the proxy service performance caused by multiple copies of the packet in the user mode and the kernel mode during the forwarding process can be avoided, thereby realizing the zero-copy packet forwarding based on the user mode protocol stack and effectively improving the system performance. In addition, according to the packet forwarding method of the present application, there is no need to create a fictitious intermediary and there is no risk of a man-in-the-middle attack, and TLS encryption, etc. are supported, which improves the security and reliability of the packet forwarding.

The embodiments of the present application also provide a proxy node device that includes: a memory, a processor, and a computer program that is stored in the memory and is capable of running on the processor. The computer program executed by the processor performs the operations of the above-described method for forwarding packets for a heterogeneous network.

According to the device of the proxy node in the embodiments of the present application, packet forwarding can be performed at the transport layer of the proxy node, which makes it possible to avoid the problem of a “bottleneck” in the performance of the proxy service caused by multiple copies of a packet in user mode and kernel mode during the forwarding process.

Brief description of the drawings

Fig. 1 shows a diagram of a proxy service in related fields of technology.

Fig. 2 is a diagram of a packet forwarding device for a heterogeneous network in accordance with some embodiments of the present application.

Fig. 3 is a diagram of a packet forwarding device for a heterogeneous network in accordance with some embodiments of the present application.

Fig. 4 is a block diagram of a packet forwarding device for a heterogeneous network in accordance with some embodiments of the present application.

Fig. 5 is a block diagram of establishing a connection between a client and a server in accordance with some embodiments of the present application.

Fig. 6 is a block diagram of a method for packet interaction for a heterogeneous network in accordance with some embodiments of the present application.

Detailed description of embodiments

In order to describe in more detail the technical means used in the embodiments of the present application to achieve the given purpose, as well as their effectiveness, the present application is described in detail below in conjunction with the accompanying drawings and exemplary embodiments.

As shown in Fig. 1, in related fields of technology, the proxy service between client A and server B is a pseudo-transparent technology, such as HAProxy. The operation process of the proxy service is described in detail below.

Client A initiates a connection request to server B, and proxy server P intercepts the connection request and masquerades as server B to complete the three-way handshake with client A.

When client A initiates a service request, proxy server P masquerades as client A to establish a connection to server B and initiates the request.

Server B sends a response message to proxy P, the proxy process receives the response message and looks for a connection from client A; and proxy P finds a matching connection and masquerades as server B to send a response message to client A.

In the above technical solution, the proxy server P is transparent to both client A and server B, but it still needs to establish a connection with client A and server B respectively, and there is a risk of man-in-the-middle attack, so it is not possible to support encryption channels such as TLS and HTTP Security (HTTPS). In addition, in the forwarding process, data streams must be received at the application layer and sent from the application layer to the destination node, and multiple copies are created between the kernel mode and the user mode, which causes a performance bottleneck.

As shown in Fig. 2 and Fig. 4, a packet forwarding method for a heterogeneous network according to some embodiments of the present application includes the following operations S101 and S102.

In step S101, a connection request sent by the client is received, and the connection request is sent to the server to establish a connection between the client and the server.

In step S102, an interaction packet is forwarded between the client and the server based on the user mode protocol stack.

It should be noted that according to the present application, as shown in Fig. 2, a proxy node is installed between the client and the server. The proxy node is configured to forward the interaction packet between the client and the server. In addition, the proxy node in the embodiments according to the present application performs packet forwarding through the transport layer. Thus, the proxy node can implement a transparent proxy service and packet forwarding based on the user mode protocol stack.

According to the packet forwarding method for a heterogeneous network in the embodiments of the present application, by performing packet forwarding at the transport layer, it is possible to avoid the bottleneck problem in the proxy service performance caused by multiple copies of a packet in the user mode and kernel mode during forwarding, thereby realizing zero-copy packet forwarding based on the user mode protocol stack and effectively improving the system performance. In addition, according to the packet forwarding method of the present application, there is no need to create a dummy intermediary and there is no risk of a man-in-the-middle attack, and TLS encryption, etc., are supported, which improves the security and reliability of packet forwarding.

As shown in Fig. 5, according to some embodiments of the present application, the operation of forwarding a connection request and a response message between a client and a server includes the following operations S201-S203.

In step S201, a connection request sent by the client is received and transmitted to the server, after which the server sends a first response message to the client in response to the connection request.

In step S202, the first response message is received and transmitted to the client, after which the client sends a second response message to the server in response to the first response message.

In step S203, the second response message is received and transmitted to the server to establish a connection between the client and the server.

It should be noted that the "connection request" in this case may be a SYN request, and the "first response message" and "second response message" may be ACK packets. For example, the client may send a SYN request to the server through the proxy node, after receiving the SYN request, the server sends an ACK packet to the client through the proxy node, and after receiving the ACK packet, the client sends an ACK packet to the server through the proxy node to complete the three-way handshake between the client and the server to establish a TCP connection between the client and the server.

In some embodiments of the present application, the operation of receiving and transmitting to the server a connection request sent by the client includes the following operations.

A connection request sent by a client is accepted according to the specified default route.

Based on the connection request, a session is created and the connection request is forwarded to the server after updating the connection request address.

According to some embodiments of the present application, the contents of a session message include: a connection serial number and a window size.

It should be noted that between the transport layer and the network layer of the proxy node, a TCP Optimizer (TCPO) module is installed, which is configured to forward the TCP packet in both directions. For example, if the UE client wants to establish a connection with the SP WEB server, the UE client first initiates a SYN request with the target port 80 to the WEB server and configures a default route to forward the SYN request to the intermediate proxy node. The proxy node configures a TCP packet forwarding rule with the target port 80 in the protocol stack, and the IP layer sends the packet to the TCPO module for processing. The TCPO module creates a session, records the sequence number of the new TCP connection, the window size and other information, updates the MAC address according to the routing address, and then forwards the packet through the network adapter. For example, if the client sends a packet to the server, the TCPO module updates the MAC address of the client to the MAC address of the proxy node according to the routing address and sends the packet to the server through the network adapter. The source IP address and port of the connection establishment packet obtained by the server come from the client UE to send a SYN+ACK packet to the client UE.

As shown in Fig. 3 and Fig. 6, in some embodiments of the present application, the operation of forwarding an interaction packet between a client and a server based on a user mode protocol stack includes the following operations S401 S404.

In step S401, a request packet sent by the client is received, and a first response packet is sent to the client in response to the request packet.

In step S402, a request packet is added first and forwarded to the server, after which the server sends a second response packet in response to the request packet.

In step S403, the second response packet is received, and an acknowledgement packet based on the second response packet is sent to the server.

In step S404, the second response packet is added to the second buffer queue and sent to the client.

It should be noted that, as shown in Fig. 3, after the three-way handshake for establishing a connection between the client and the server is completed, the client can send a request packet to the server. The specified default route forwards the request packet to the proxy node. The TCPO module of the proxy node receives the request packet, adds the request packet to the buffer queue A to forward the request packet to the server, and sends an ACK packet to the client. After receiving the second response packet from the server, the TCPO module adds the second response packet to the queue B to forward the second response packet to the client, and sends an ACK packet to the server to acknowledge receipt of the data.

According to some embodiments of the present application, the method further comprises the following: if the data capacity of the second response packet in the second buffer queue is greater than a threshold value, the window size of the request packet sent to the server is reduced to reduce the packet sending rate of the server. As shown in Fig. 3, if the network on the client side creates too much unallocated data in the buffer queue B, the window size of the advertisement sent to the server can be reduced to inform the server of the reduction in the data transmission rate. In this way, optimization is realized in the process of packet interaction and problems of congestion, packet loss, etc. are effectively solved.

In some embodiments of the present application, the method further comprises the following: if the client does not receive the second response packet within a predetermined period of time, the second response packet is again added to the second buffer queue and sent to the client. As shown in Fig. 3, the data in the buffer queue B is taken out of the queue one by one, and the data packet is forwarded to the client. When receiving the ACK packet, the proxy node can immediately remove the corresponding packet from the queue. A retransmission timer can be set. If the client does not receive the data packet within a predetermined period of time, the client can retransmit the response packet. In this way, the packet loss problem is effectively prevented.

According to some embodiments of the present application, the method further comprises the following: if a packet loss is detected during the packet interaction process, the packet interaction window size is adjusted to a predetermined threshold. It should be noted that the "predetermined threshold" here may be a "slow start threshold". The slow start threshold may be understood as the maximum value of the slow start during the packet sending process. By setting the window size equal to the slow start threshold, the slow start stage can be skipped and directly proceed to the congestion avoidance stage, and thus the packet interaction process between the client and the server is optimized and accelerated.

As shown in Fig. 2 and Fig. 3, a packet forwarding device for a heterogeneous network according to some embodiments of the present application includes a forwarding module. The forwarding module may be a TCPO module configured to forward a connection request and a response message between a client and a server, establish a connection between the client and the server, and forward an interaction packet between the client and the server based on a user mode protocol stack.

According to the packet forwarding device for a heterogeneous network in the embodiments of the present application, by performing packet forwarding at the transport layer by the forwarding module, it is possible to avoid the bottleneck problem in the proxy service performance caused by multiple copies of a packet in the user mode and kernel mode during forwarding, thereby realizing zero-copy packet forwarding based on the user mode protocol stack and effectively improving the system performance. In addition, according to the packet forwarding device of the present application, there is no need to create a dummy intermediary and there is no risk of a man-in-the-middle attack, and TLS encryption etc. are supported, which improves the security and reliability of packet forwarding.

In the machine-readable information carrier, according to the embodiments of the present application, a program for implementing the transmission of information is stored. The program executed by the processor performs the operations of the above-described method for forwarding packets for a heterogeneous network.

According to the machine-readable medium in the embodiments of the present application, by implementing the packet forwarding method for a heterogeneous network, the packet forwarding can be performed at the transport layer of the proxy node, and the bottleneck problem in the proxy service performance caused by multiple copies of the packet in the user mode and the kernel mode during the forwarding process can be avoided, thereby realizing the zero-copy packet forwarding based on the user mode protocol stack and effectively improving the system performance. In addition, according to the packet forwarding method of the present application, there is no need to create a fictitious intermediary and there is no risk of a man-in-the-middle attack, and TLS encryption, etc. are supported, which improves the security and reliability of the packet forwarding.

The proxy node device, in accordance with the embodiments of the present application, includes: a memory, a processor, and a computer program that is stored in the memory and is capable of running on the processor. The computer program, executed by the processor, performs the operations of the above-described method for forwarding packets for a heterogeneous network.

According to the device of the proxy node in the embodiments of the present application, packet forwarding can be performed at the transport layer of the proxy node device, and the bottleneck problem in the performance of the proxy service caused by multiple copies of the packet in the user mode and the kernel mode during the forwarding process can be avoided, thereby realizing zero-copy packet forwarding based on the user mode protocol stack and effectively improving the performance of the system. In addition, according to the packet forwarding method of the present application, there is no need to create a dummy intermediary and there is no risk of a man-in-the-middle attack, and TLS encryption, etc., are supported, which improves the security and reliability of packet forwarding.

It should be noted that Intel is launching a Data Plane Development Kit (DPDK) project that supports sending and receiving user-mode network packets. Currently, the DPDK sending and receiving system is mainly used to forward packets between network devices. In the embodiments of the present application, the DPDK is used as a sending and receiving structure of a transparent proxy server, and the open source Berkeley Software Distribution (BSD) TCP/IP protocol stack is used as a user-mode protocol stack. Other user-mode protocol stacks may also be used.

Taking as an example that a mobile phone user accesses web pages through a browser, a packet forwarding method and device for a heterogeneous network according to the embodiments of the present application are provided below. As shown in Fig. 2 and Fig. 3, a proxy node is embedded between the user side (UE) and the service provider (SP), transparent packet forwarding is realized based on the DPDK+ user mode TCP/IP protocol stack, and the TCP protocol stack is optimized and accelerated according to the data transmission characteristics of wireless networks, so as to improve Internet access for mobile users. As shown in Fig. 2 and Fig. 3, a specific process is described as follows.

The UE client initiates a SYN request with target port 80 to the SP WEB server and configures a default route to direct the SYN request to the intermediate proxy node.

The proxy node configures a TCP packet forwarding rule with the target port 80 in the protocol stack, and the IP layer sends the packet to the TCP module for processing.

The TCPO module creates a session, records the new TCP connection sequence number, window size, and other information, updates the MAC address to match the routing address, and then sends the packet through the network adapter.

The source IP address and port of the connection establishment packet received by the SP are from the UE client to send the SYN+ACK packet to the UE.

The proxy node forwards the packet from the SP to the TCPO module, and the TCPO module forwards SYN+ACK packets to the UE.

The UE receives the SYN+ACK packet and sends an ACK packet, the SP receives the ACK packet, and the UE completes the three-way handshake with the SP.

The UE client sends a GET request to the TCPO module.

The TCPO module receives the data packet, places the data packet into the buffer queue A, sends an ACK packet to the UE, and forwards the request packet to the SP.

The TCPO module receives the response packet sent by the SP, puts the response packet into the buffer queue B, and sends an ACK packet to the SP to acknowledge the receipt of the data. If the network on the UE side creates a large amount of unallocated data in the queue B, the size of the advertisement window sent to the SP is reduced, and the SP is informed to reduce the data transmission rate.

The data packets in buffer queue B are dequeued one at a time and transmitted to the client. A retransmission timer is set, and if the timer expires, the specified packet is retransmitted, and the packet in the queue is removed immediately after receiving an ACK.

The UE actively releases the connection. The TCPO transparently transmits the acknowledgement packet four times and releases the connection with the SP.

After receiving a connection release request from the SP, if there are undistributed messages in queue B, the TCPO masquerades as a UE to release the connection with the SP, and then releases the connection with the UE after the data in queue B is completely sent.

Implementing packet forwarding between the client and the server using the above proxy node has the following advantages.

(1) Fully transparent proxy: As shown in Fig. 2, the proxy node forwards the packet at the TCP layer and changes the physical address at the IP layer. The transparent forwarding process of the three-way handshake can replace the entire handshake process compared with the traditional proxy process. The TCPO module is installed between L3 (network layer) and L4 (transport layer) of the user mode TCP/IP protocol stack to realize the transparent proxy function. The UE initiates a request, which is forwarded to the proxy by default, when passing through the TCPO module, the request is directly forwarded to the SP network, the source and destination IP addresses remain unchanged, and the L2 (Ethernet layer) address is filled in based on the actual route. The packet sent from the SP to the UE is forwarded to the UE through the TCPO. The proxy only forwards the TCP packet and does not perform packet assembly and disassembly. There is no need to copy, read and write the packet, there is no need to establish communication between UE and SP, so there is no risk of man-in-the-middle attack, and TLS transmission encryption etc. are also supported.

(2) TCP acceleration optimization: The TCPO module of the transparent proxy node divides the TCP connection between the UE and the SP into two segments and flexibly controls the advertisement window size; the TCPO module changes the advertisement window size according to the length of the buffer queue to control the data transmission rate of the source side. The TCPO module optimizes the forwarding performance of TCP packets through buffering, congestion control and other mechanisms based on the transmission characteristics of the wireless network environment and the behavior characteristics of mobile users, thereby reducing the degradation of Internet access speed caused by wireless transmission disruption, packet loss and other problems, and improving the Internet access quality for 2G/3G/4G mobile users.

(3) Support segmented connection teardown: The node that tears down the connection actively tears down the connection immediately, and the other side waits for the data to be completely sent before tearing down the connection.

(4) Bidirectional data buffering: After receiving ACK, the data packet is removed from the buffer queue to perform data buffering.

(5) Support retransmission timeout: The data packet is retransmitted from the buffer queue without the need for the original sender to retransmit the data.

(6) Flexible congestion control: After packet loss is detected, the initial window size is set to the slow start threshold value, and the slow start stage is skipped, and then the congestion avoidance stage itself begins.

(7) Support packet sorting: Out-of-order packets will not affect the proxy node's packet forwarding.

In conclusion, according to the proxy service schemes presented in the embodiments of the present application, by embedding the TCPO module, which is configured to bidirectionally forward a TCP packet, into the TCP/IP protocol stack of the user mode, a fully transparent proxy service is realized, TCP optimization logic is added, and the quality of access to the client network is improved. Thus, not only is the performance bottleneck of the traditional proxy server eliminated, but an open system for TCP optimization is provided, which ensures the stability and reliability of the native protocol stack, and facilitates the implementation of individual policies for services.

It is obvious that those skilled in the art should understand that the above modules and operations of the embodiments of the present application can be implemented by a general-purpose computing device, and they can be centralized in a single computing device or distributed over a network consisting of a plurality of computing devices. The above modules and operations can be implemented by a program code that can be executed by a computing device, and they can be stored in a memory device and executed by the computing device. In some situations, the operations shown or described can be performed in an order different from that described herein; or they can exist in the form of integrated circuit modules, respectively; or several of the modules and operations mentioned can be composed into a single integrated circuit module for implementation. Therefore, the present application is not limited to any particular combination of hardware and software.

By describing exemplary embodiments, it is possible to obtain a deeper and more specific understanding of the technical means used in the embodiments of the present application to achieve the intended purpose and effectiveness. However, the accompanying drawings are provided for reference and example only and do not limit the present application.

Claims (24)

1. A packet forwarding method for a heterogeneous network, including: receiving a connection request sent by the client and forwarding the connection request to the server to establish a connection between the client and the server; and forwarding the interaction packet between the client and the server based on the user mode protocol stack; wherein the forwarding of the interaction packet between the client and the server based on the user mode protocol stack includes: receiving a request packet sent by the client and sending a first response packet to the client in response to the request packet; adding a request packet to the first buffer queue and forwarding the request packet to the server so that the server sends a second response packet in response to the request packet; receiving a second response packet and sending an acknowledgment packet to the server based on the second response packet; and adding the second response packet to the second buffer queue and sending the second response packet to the client. 2. A method for forwarding packets for a heterogeneous network according to paragraph 1, characterized in that establishing a connection between the client and the server includes: receiving a connection request sent by a client and forwarding the connection request to the server so that the server sends a first response message to the client in response to the connection request; receiving a first response message and forwarding the first response message to the client so that the client sends a second response message to the server in response to the first response message; and receiving the second response message and forwarding the second response message to the server to establish a connection between the client and the server. 3. A method for forwarding packets for a heterogeneous network according to paragraph 2, characterized in that receiving a request to establish a connection sent by the client and forwarding the request to establish a connection to the server includes: receiving a connection request sent by the client in accordance with the specified default route; and creating a session based on a connection request, and forwarding the connection request to the server after updating the connection request address. 4. A method for forwarding packets for a heterogeneous network according to paragraph 3, characterized in that the contents of the session message include: a connection serial number and a window size. 5. A method for forwarding packets for a heterogeneous network according to paragraph 1, additionally including: if the data capacity of the second response packet in the second buffer queue is greater than the threshold value, the window size of the request packet sent to the server is reduced to reduce the packet sending rate by the server. 6. A method for forwarding packets for a heterogeneous network according to paragraph 1, additionally including: if the client does not receive the second response packet within a predetermined period of time, add the second response packet back to the second buffer queue and send the second response packet to the client. 7. A method for forwarding packets for a heterogeneous network according to paragraph 1, additionally including: If packet loss is detected during the packet interaction process, the packet interaction window size is adjusted to a specified threshold value. 8. A machine-readable medium on which a program for transmitting information is stored, wherein the program, when executed by the processor, performs the operations of the method for forwarding packets for a heterogeneous network in accordance with any of paragraphs 1-7. 9. A proxy node device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, performs the operations of the packet forwarding method for a heterogeneous network in accordance with any of paragraphs 1-7.