CN115632985B - Multipath load balancing NAT gateway forwarding method and system based on P4 - Google Patents

Abstract

The present invention discloses a multi-path load balancing NAT gateway forwarding method and system based on P4, the method comprising: an SDN controller obtains a weighted hash load balancing strategy flow table according to a bandwidth-delay product, and sends the weighted hash load balancing strategy flow table to a P4 programmable switch; the P4 programmable switch selects a forwarding link according to the weighted hash load balancing strategy flow table and performs load balancing NAT gateway forwarding. The present invention can be implemented based on the P4 language, obtains path quality by active detection for weighting, and performs route selection communication by weighted hash strategy, thereby improving network reliability while having certain flexibility and scalability.

Description

A multi-path load balancing NAT gateway forwarding method and system based on P4

Technical Field

The present invention relates to the technical field of network communication, and in particular to a multi-path load balancing NAT gateway forwarding method and system based on P4.

Background technique

In a multi-link network environment, the peer host often selects one of the links for transmission during the communication process. In order not to waste multiple idle links and to improve network bandwidth and stability, existing solutions have proposed technologies such as multi-link aggregation and multi-path transmission protocols.

However, the current multi-link aggregation switches are mainly customized by manufacturers and are controlled by multi-link aggregation protocols, which do not have the flexibility of a control plane and a programmable data plane. The multi-path transmission protocol MPTCP integrates heterogeneous networks at the protocol level to improve stability. However, the MPTCP protocol is not popular at present, and the performance is reduced if there is a large difference in bandwidth and delay between multiple links.

Therefore, the prior art still needs to be improved and developed.

Summary of the invention

The technical problem to be solved by the present invention is that, in view of the above-mentioned defects of the prior art, a multi-path load balancing NAT gateway forwarding method and system based on P4 is provided, aiming to solve the problem that the prior art does not have the flexibility of a control plane plus a programmable data plane and the performance is reduced when there is a large bandwidth delay difference between multiple links.

The technical solution adopted by the present invention to solve the technical problem is as follows:

In a first aspect, the present invention provides a multi-path load balancing NAT gateway forwarding method based on P4, wherein the method comprises:

The SDN controller obtains a weighted hash load balancing strategy flow table according to the bandwidth-delay product, and sends the weighted hash load balancing strategy flow table to the P4 programmable switch;

The P4 programmable switch selects a forwarding link according to the weighted hash load balancing policy flow table and performs load balancing NAT gateway forwarding.

In one implementation, the SDN controller obtains a weighted hash load balancing strategy flow table according to the bandwidth-delay product, and before sending the weighted hash load balancing strategy flow table to the P4 programmable switch, it also includes:

The SDN controller is enabled and sends an initialization flow table to the P4 programmable switch to achieve intercommunication between IP addresses in the same network segment on the LAN side accessing the P4 programmable switch, and intercommunication between the NAT gateway IP address of the P4 programmable switch and the external network IP address of the peer end.

In one implementation, the SDN controller obtains a weighted hash load balancing strategy flow table according to the bandwidth-delay product, and sends the weighted hash load balancing strategy flow table to the P4 programmable switch, including:

The SDN controller periodically sends a detection packet to each link to obtain a reply packet;

According to the returned packet, the bandwidth Bandwidth and delay Delay of each link are obtained;

According to the bandwidth Bandwidth and delay Delay of each link, a bandwidth-delay product BDP=Bandwidth×Delay of each link is obtained;

According to the proportion of the bandwidth delay product BDP, a hash load balancing weight of each link is obtained;

According to the hash load balancing weight of each link, the weighted hash load balancing strategy flow table is obtained;

The weighted hash load balancing strategy flow table is sent to the P4 programmable switch.

In one implementation, the P4 programmable switch selects a forwarding link and performs load balancing NAT gateway forwarding according to the weighted hash load balancing policy flow table, including:

The P4 programmable switch receives a data packet from an access host and selects a forwarding link according to the weighted hash load balancing strategy flow table;

Delivering the data packet to the corresponding NAT gateway exit of the P4 programmable switch according to the forwarding link;

The NAT gateway egress of the P4 programmable switch performs source IP network address conversion on the data packet and sends the data packet to the peer server through the forwarding link.

In one implementation, the P4 programmable switch receives a data packet from an access host, and before selecting a forwarding link based on the weighted hash load balancing policy flow table, further includes:

After the access host is connected to the LAN port of the P4 programmable switch, the SDN controller automatically allocates an IP address to the access host through the DHCP dynamic host configuration protocol.

In one implementation, after the NAT gateway egress of the P4 programmable switch performs source IP network address conversion on the data packet and sends the data packet to the peer server through the forwarding link, it also includes:

After receiving the reply packet from the peer server, the NAT gateway exit of the P4 programmable switch converts the destination IP network address of the reply packet and sends it to the access host.

In one implementation, the method further includes:

The SDN controller regenerates and sends the weighted hash load balancing strategy flow table to the P4 programmable switch in each cycle of sending a detection packet.

In a second aspect, an embodiment of the present invention further provides a multi-path load balancing NAT gateway forwarding system based on P4, wherein the system comprises: an SDN controller and a P4 programmable switch;

The SDN controller is used to obtain a weighted hash load balancing strategy flow table according to the bandwidth-delay product, and send the weighted hash load balancing strategy flow table to the P4 programmable switch;

The P4 programmable switch is used to select a forwarding link according to the weighted hash load balancing policy flow table and perform load balancing NAT gateway forwarding.

In one implementation, the SDN controller is specifically used to:

Periodically send a probe packet to each link to get a reply packet;

According to the returned packet, the bandwidth Bandwidth and delay Delay of each link are obtained;

According to the bandwidth Bandwidth and delay Delay of each link, a bandwidth-delay product BDP=Bandwidth×Delay of each link is obtained;

According to the proportion of the bandwidth delay product BDP, a hash load balancing weight of each link is obtained;

According to the hash load balancing weight of each link, the weighted hash load balancing strategy flow table is obtained;

The weighted hash load balancing strategy flow table is sent to the P4 programmable switch.

In one implementation, the P4 programmable switch is specifically used for:

Receive a data packet from an access host and select a forwarding link according to the weighted hash load balancing strategy flow table;

Delivering the data packet to the corresponding NAT gateway exit of the P4 programmable switch according to the forwarding link;

The NAT gateway egress of the P4 programmable switch performs source IP network address conversion on the data packet and sends the data packet to the peer server through the forwarding link.

In one implementation, the SDN controller is further configured to:

In each cycle of sending a detection packet, the weighted hash load balancing strategy flow table is regenerated and sent to the P4 programmable switch.

In a third aspect, an embodiment of the present invention further provides a processing device, wherein the processing device includes a memory, a processor, and a P4-based multi-path load balancing NAT gateway forwarding program stored in the memory and executable on the processor, and when the processor executes the P4-based multi-path load balancing NAT gateway forwarding program, the steps of the P4-based multi-path load balancing NAT gateway forwarding method as described in any one of the above items are implemented.

In a fourth aspect, an embodiment of the present invention also provides a storage medium, wherein the storage medium stores one or more programs, and the one or more programs can be executed by one or more processors to implement the steps of a multi-path load balancing NAT gateway forwarding method based on P4 as described in any of the above items.

Beneficial effect: Compared with the prior art, the present invention provides a multi-path load-balancing NAT gateway forwarding method based on P4. The present invention first obtains the bandwidth-delay product of the link through the SDN controller, and obtains the weighted hash load-balancing strategy flow table according to the bandwidth-delay product to achieve quantitative evaluation of the quality of each link, and then sends the weighted hash load-balancing strategy flow table to the P4 programmable switch. The P4 programmable switch can select the forwarding link according to the weighted hash load-balancing strategy flow table and perform load-balancing NAT gateway forwarding, thereby realizing the writing of the P4 language, so that the switch has better flexibility and scalability when selecting links.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

FIG1 is a schematic flow chart of a multi-path load balancing NAT gateway forwarding method based on P4 according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a link detection process provided by an embodiment of the present invention.

FIG3 is a schematic diagram of a load balancing NAT gateway forwarding process in a dual-link network aggregation scenario provided by an embodiment of the present invention.

FIG4 is a principle block diagram of a multi-path load balancing NAT gateway forwarding system based on P4 provided in an embodiment of the present invention.

FIG. 5 is a schematic diagram of the structure of a processing device provided in an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

In a multi-link network environment, the peer host often selects one of the links for transmission during the communication process. In order to avoid wasting multiple idle links and improve network bandwidth and stability, existing solutions have proposed technologies such as multi-link aggregation and multi-path transmission protocols. However, current multi-link aggregation switches are mainly customized by manufacturers and are controlled by multi-link aggregation protocols, which do not have the flexibility of control plane plus programmable data plane. The emerging multi-path transmission protocol MPTCP integrates heterogeneous networks at the protocol level to improve stability. However, the MPTCP protocol is currently not popular, and if there is a large gap in bandwidth and delay between multiple links, the performance will be unsatisfactory.

Therefore, in order to solve the above problems, the present invention discloses a multi-path load balancing NAT gateway forwarding method and system based on P4. First, the bandwidth-delay product of the link is obtained through the SDN controller, and the weighted hash load balancing strategy flow table is obtained according to the bandwidth-delay product to achieve quantitative evaluation of the quality of each link. Then, the weighted hash load balancing strategy flow table is sent to the P4 programmable switch. The P4 programmable switch can select the forwarding link according to the weighted hash load balancing strategy flow table and perform load balancing NAT gateway forwarding, thereby realizing it through the writing of P4 language, so that the switch has better flexibility and scalability in link selection.

Exemplary Methods

This embodiment provides a multi-path load balancing NAT gateway forwarding method based on P4. As shown in Figure 1, the method includes the following steps:

Step S100: The SDN controller obtains a weighted hash load balancing strategy flow table according to the bandwidth-delay product, and sends the weighted hash load balancing strategy flow table to the P4 programmable switch.

The network layer can be decomposed into two interacting parts, namely the data plane and the control plane. Traditionally, the control plane routing protocol and the data plane forwarding function have been implemented as a whole and located in a router. Among them, the data plane: that is, the forwarding function of each router in the network layer, which determines how the datagram arriving at one of the input links of the router is forwarded to one of the output links of the router. The control plane: as a network-wide logic, it not only controls how the routers along the end-to-end path from the source host to the destination host forward datagrams, but also controls how the network layer components and services are configured and managed.

The SDN controller is in the control plane, while the P4 programmable switch is in the data plane.

Among them, the SDN (Software-defined Network) controller is an application in the software-defined network that is responsible for traffic control to ensure an intelligent network. Among them, the SDN controller is based on protocols such as OpenFlow, which allows the server to tell the switch where to send data packets.

P4 (Programming Protocol-Independent Packet Processors) network programming language is mainly used in network devices such as network cards, switches, and routers, allowing users to program to control the forwarding behavior of packets in the data plane. P4 programmable switches based on the P4 network programming language reduce network layers, reduce network complexity, and save construction costs. Compared with traditional switches, the data plane functions of P4 programmable switches are not fixed in advance, but are determined by the P4 program. The data configures the plane at initialization to implement the functions described by the P4 program, and there is no built-in knowledge of existing network protocols. The control plane communicates with the data plane using the same channels as function-specific switches, but the table collection and other objects in the data plane are no longer fixed because they are defined by the P4 programmable switch and the API used by the control plane to communicate with the data plane is generated by the P4 compiler. Therefore, the P4 programmable switch can be said to be protocol-independent, which enables programmers to freely implement a set of protocols and other data plane behaviors.

This embodiment is applicable to multi-link network aggregation scenarios. The multi-link network is configured and managed based on the SDN control plane plus the programmable switch P4. The SDN controller sends the load balancing policy to the programmable switch P4 through the weighted hash load balancing policy flow table, so that the P4 programmable switch can act as a NAT gateway while performing load balancing routing.

In one implementation, the following steps are included before step S100 in this embodiment:

Step S10, the SDN controller is enabled and sends an initialization flow table to the P4 programmable switch to achieve intercommunication between the IP addresses on the same network segment of the LAN side accessing the P4 programmable switch, and intercommunication between the NAT gateway IP address of the P4 programmable switch and the external network IP address of the peer end.

Specifically, the SDN controller enables and sends down the initialization flow table, such as ARP, LLDP layer 2 link flow table, L3 layer 3 forwarding flow table, and the multi-link channel can work normally. The P4 programmable switch starts, and the layer 2 link forwarding table t_mac_lpm, layer 3 network forwarding table t_ipv4_lpm, layer 3 detection table t_probe_lpm, and NAT forwarding table t_nat_lpm work effectively.

In one implementation, step S100 in this embodiment includes the following steps:

Step S101: The SDN controller periodically sends a detection packet to each link to obtain a reply packet.

Specifically, taking the dual-link scenario as an example, as shown in Figure 2, after the SDN controller sends the initialization flow table, it can monitor the available links normally, and then create a periodic task to actively send detection packets to each link. The detection packet can be an ICMP packet, and the interval and number of times are set, such as an interval of 0.2s, 10 detections, and the detection packet is sent to the next hop peer IP through the physical port of each link. Among them, the scenarios shown in Figure 2 are 3.3.3.11 and 4.4.4.11 respectively. The logical port IP address of the P4 gateway is 2.2.2.11. After SNAT (source IP network address translation) (1.1.1.11→2.2.2.11), the destination MAC is changed to the next hop ETH1 and ETH2 addresses. ETH1 and ETH2 reply after receiving the detection packet. After the reply packet reaches P4 through their respective links, it is converted by DNAT (2.2.2.11→1.1.1.11) to the address of the controller CONTROLLER. The destination MAC is also changed to the MAC of the controller, thereby completing a detection of each link. The table entry that mainly implements the function is t_probe_lpm.

Step S102: Obtain the bandwidth and delay of each link according to the returned packet;

Step S103: According to the bandwidth Bandwidth and delay Delay of each link, obtain the bandwidth delay product BDP of each link = Bandwidth × Delay;

Step S104: Obtain a hash load balancing weight for each link according to the proportion of the bandwidth delay product BDP;

Step S105, obtaining the weighted hash load balancing strategy flow table according to the hash load balancing weight of each link;

Step S106: Send the weighted hash load balancing strategy flow table to the P4 programmable switch.

Specifically, the working status of multiple links can be monitored on the UI interface of the SDN controller, including the bandwidth-delay product BDP transmitted back by each link after subsequent active detection, that is, the link quality. The SDN controller initiates a scheduled periodic task, sends a detection packet to the opposite router through each link, calculates the bandwidth Bandwidth and delay Delay of each link based on the return packet, and then calculates the link bandwidth-delay product BDP = Bandwidth × Delay, and displays it on the controller interface. Then, based on the proportion of each link's bandwidth-delay product in all links as the weight of the hash load balancing algorithm, the controller sends the new weighted hash load balancing strategy flow table to the P4 data plane.

As shown in Figure 2, the dual links are named L1 and L2 respectively, and the weights and operators of hash load balancing are shown in Table 1. Different from the ordinary hash load balancing strategy, the ordinary hash load balancing strategy is random when communicating, for example, when HOST1 accesses HOST2, that is, a random path is selected from L1 and L2 for transmission. The weighted hash load balancing strategy in this embodiment selects the path for transmission based on the bandwidth-delay product as the weight factor, that is, according to the weighted hash algorithm, the higher the weight, the greater the probability of being selected, and the higher the link quality and the higher the bandwidth-delay product in the present invention, the higher the probability of being selected for transmission.

Table 1. Weight calculation table

link Bandwidth-Delay Product Weights Hash Operator L1 BDP1＝Bandwidth1×Delay1 W1＝BDP1/(BDP1+BDP2) Hash(W1) L2 BDP2＝Bandwidth2×Delay2 W2＝BDP2/(BDP1+BDP2) Hash(W2)

It should be noted that the hash load balancing weight of each link can also be obtained through balancing algorithms such as destination IP hash, source IP hash, weighted source IP hash, source IP port hash, ISP algorithm, minimum bandwidth, weighted minimum bandwidth, minimum number of connections, polling, weighted polling, and dynamic proximity.

Step S200: The P4 programmable switch selects a forwarding link according to the weighted hash load balancing policy flow table and performs load balancing NAT gateway forwarding.

Specifically, the main functions of the P4 programmable switch in data plane forwarding include link layer and network layer forwarding intercommunication. The controller acts as an access terminal to actively detect the entire link, match the address of the access host and perform load balancing NAT forwarding. Therefore, the P4 Pipeline pipeline needs to design the table entries according to the above requirements, as shown in Table 2:

Table 2. Table entry design of P4 programmable switch

In one implementation, step S200 in this embodiment includes the following steps:

Step S201, the P4 programmable switch receives a data packet from an access host and selects a forwarding link according to the weighted hash load balancing strategy flow table;

Step S202: delivering the data packet to the corresponding NAT gateway exit of the P4 programmable switch according to the forwarding link;

Step S203: The NAT gateway egress of the P4 programmable switch performs source IP network address conversion on the data packet, and sends the data packet to the peer server through the forwarding link.

Specifically, when the host is connected to the LAN port of the P4 programmable switch and communicates with the outside world, the forwarding link is selected based on the weighted hash load balancing policy flow table. The packet passes through the forwarding link and reaches the NAT gateway exit of the P4 programmable switch. Then the P4 programmable switch performs source IP network address translation SNAT on the packet, converting the source address into an IP address that can be routed to the next-hop peer server and sent to the peer server.

For example, taking the dual-link network aggregation scenario shown in FIG3 as an example, the present invention is applicable to the scenario where the link is greater than or equal to 2. When HOST1 accesses the host HOST2 with the external IP address 5.5.5.12, taking a packet transmission and reception as an example, the first step is to provide the MAC (00:00:03) of the egress gateway through the ARP request from the controller, and after the load balancing routing of the weighted hash load balancing strategy flow table, the physical port port3 is selected as the egress. Assuming that the logical port IP address of the P4 gateway is 2.2.2.12, after the source IP network address is converted to SNAT (1.1.1.12→2.2.2.12), the destination MAC is changed to the ETH1 address of the next hop, and then forwarded by the peer service routing, it is delivered to the correct destination HOST2. If the communication is within the same network segment, such as HOST1 accessing the controller CONTROLLER (1.1.1.12→1.1.1.11), the controller performs Layer 2 forwarding through the t_mac_lpm forwarding table after completing the ARP proxy reply. Unlike accessing the external network, the weighted hash strategy and NAT gateway forwarding are no longer performed. However, for the access host HOST1, whether accessing the internal network or the external network, this process is not perceived.

In one implementation, the following steps are included before step S200 in this embodiment:

Step S20: After the access host is connected to the LAN port of the P4 programmable switch, the SDN controller automatically allocates an IP address to the access host through the DHCP dynamic host configuration protocol.

For example, this embodiment takes the dual link of FIG. 3 as an example. After HOST1 is connected to the LAN port of the P4 programmable switch, the SDN controller allocates an IP address 1.1.1.12 to HOST1 through the DHCP dynamic host configuration protocol.

In one implementation, the following steps are included after step S203 in this embodiment:

Step S204: After receiving the reply packet from the peer server, the NAT gateway egress of the P4 programmable switch converts the destination IP network address of the reply packet and sends it to the access host.

Specifically, after the return packet from the outside is routed through the peer server to the NAT gateway port of the P4 programmable switch, the P4 programmable switch performs destination IP network address translation DNAT on the return packet, converting the address into the IP address of the host sending the packet, thus completing a round of communication.

For example, taking the dual-link network aggregation scenario shown in Figure 3 as an example, the reply packet of HOST2 is forwarded to port 3 of P4 through the peer service routing, and then converted to the correct HOST1 address by the destination IP network address translation DNAT (2.2.2.12→1.1.1.12), and the destination MAC is also changed to the MAC of HOST1, thereby completing the external communication. The table entry that mainly implements the function is t_hash_nat.

In one implementation, the method described in this embodiment further includes:

Step M100: The SDN controller regenerates and sends the weighted hash load balancing policy flow table to the P4 programmable switch in each cycle of sending a detection packet.

Specifically, the SDN controller actively detects each link periodically, updates and sends the weighted hash load balancing policy flow table to the P4 programmable switch in each cycle, and then starts a new round of detection tasks.

Exemplary Systems

Furthermore, the present invention also provides a P4-based multi-path load balancing NAT gateway forwarding system, as shown in FIG4 , the system includes: an SDN controller and a P4 programmable switch;

The SDN controller is used to obtain a weighted hash load balancing strategy flow table according to the bandwidth-delay product, and send the weighted hash load balancing strategy flow table to the P4 programmable switch;

The P4 programmable switch is used to select a forwarding link according to the weighted hash load balancing policy flow table and perform load balancing NAT gateway forwarding.

In one implementation, the SDN controller described in this embodiment is specifically used for:

Periodically send a probe packet to each link to get a reply packet;

According to the returned packet, the bandwidth Bandwidth and delay Delay of each link are obtained;

According to the bandwidth Bandwidth and delay Delay of each link, a bandwidth-delay product BDP=Bandwidth×Delay of each link is obtained;

According to the proportion of the bandwidth delay product BDP, a hash load balancing weight of each link is obtained;

According to the hash load balancing weight of each link, the weighted hash load balancing strategy flow table is obtained;

The weighted hash load balancing strategy flow table is sent to the P4 programmable switch.

In one implementation, the P4 programmable switch in this embodiment is specifically used for:

Receive a data packet from an access host and select a forwarding link according to the weighted hash load balancing strategy flow table;

Delivering the data packet to the corresponding NAT gateway exit of the P4 programmable switch according to the forwarding link;

The NAT gateway egress of the P4 programmable switch performs source IP network address conversion on the data packet and sends the data packet to the peer server through the forwarding link.

In one implementation, the SDN controller described in this embodiment is further used for:

In each cycle of sending a detection packet, the weighted hash load balancing strategy flow table is regenerated and sent to the P4 programmable switch.

Referring to FIG. 5 , it is a schematic diagram of the structure of a multi-path load balancing NAT gateway forwarding processing device based on P4 provided in an embodiment of the present invention. The processing device 1300 shown in FIG. 5 includes one or more processors 1301, a communication interface 1302, and a memory 1303. The processor 1301, the communication interface 1302, and the memory 1303 can be connected via a bus, or can communicate via other means such as wireless transmission. The embodiment of the present invention takes the connection via bus 1304 as an example, wherein the memory 1303 is used to store instructions for executing instructions stored in the memory 1303. The memory 1303 stores program code, and the processor 1301 can call the program code stored in the memory 1303 to implement the relevant functions of the multi-path load balancing NAT gateway forwarding processing device 1300 based on P4.

It should be understood that in the embodiment of the present invention, the processor 1301 may be a central processing unit (CPU), and the processor may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

The communication interface 1302 may be a wired interface (e.g., an Ethernet interface) or a wireless interface (e.g., a cellular network interface or a wireless local area network interface) for communicating with other modules or devices. For example, in the embodiment of the present application, the communication interface 1302 may be specifically used to receive input data input by a user; or receive data from an external device, etc.

The memory 1303 may include a volatile memory, such as a random access memory (RAM); the memory may also include a non-volatile memory, such as a read-only memory (ROM), a flash memory, a hard disk drive (HDD) or a solid-state drive (SSD); the memory may also include a combination of the above types of memories. The memory may be used to store a set of program codes so that the processor can call the program codes stored in the memory to implement the related functions of the multiplier 10 as above.

It should be noted that FIG5 is only a possible implementation of the embodiment of the present invention. In practical applications, the processing device may also include more or fewer components, which is not limited here. For the contents not shown or described in the embodiment of the present invention, please refer to the relevant description in the aforementioned method embodiment, which will not be repeated here.

Those of ordinary skill in the art will appreciate that the units and implementation steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided by the present invention can include non-volatile and/or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

In summary, the present invention discloses a multi-path load balancing NAT gateway forwarding method and system based on P4, the method comprising: the SDN controller obtains a weighted hash load balancing strategy flow table according to the bandwidth delay product, and sends the weighted hash load balancing strategy flow table to the P4 programmable switch; the P4 programmable switch selects a forwarding link according to the weighted hash load balancing strategy flow table and performs load balancing NAT gateway forwarding. The present invention can be implemented based on the P4 language, obtains the path quality by active detection for weighting, and performs routing communication by weighted hash strategy, which improves the network reliability while having certain flexibility and scalability.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (11)

1. A multi-path load balancing NAT gateway forwarding method based on P4, characterized in that the method comprises: The SDN controller obtains a weighted hash load balancing strategy flow table according to the bandwidth-delay product, and sends the weighted hash load balancing strategy flow table to the P4 programmable switch; The P4 programmable switch selects a forwarding link according to the weighted hash load balancing strategy flow table and performs load balancing NAT gateway forwarding; The SDN controller obtains a weighted hash load balancing strategy flow table according to the bandwidth-delay product, and sends the weighted hash load balancing strategy flow table to the P4 programmable switch, including: The SDN controller periodically sends a detection packet to each link to obtain a reply packet; According to the returned packet, the bandwidth Bandwidth and delay Delay of each link are obtained; According to the bandwidth Bandwidth and delay Delay of each link, a bandwidth-delay product BDP=Bandwidth×Delay of each link is obtained; According to the proportion of the bandwidth delay product BDP, a hash load balancing weight of each link is obtained; According to the hash load balancing weight of each link, the weighted hash load balancing strategy flow table is obtained; The weighted hash load balancing strategy flow table is sent to the P4 programmable switch. 2. According to the multi-path load balancing NAT gateway forwarding method based on P4 in claim 1, it is characterized in that the SDN controller obtains a weighted hash load balancing strategy flow table according to the bandwidth-delay product, and before sending the weighted hash load balancing strategy flow table to the P4 programmable switch, it also includes: The SDN controller is enabled and sends an initialization flow table to the P4 programmable switch to achieve intercommunication between IP addresses in the same network segment on the LAN side accessing the P4 programmable switch, and intercommunication between the NAT gateway IP address of the P4 programmable switch and the external network IP address of the peer end. 3. According to the multi-path load balancing NAT gateway forwarding method based on P4 in claim 1, it is characterized in that the P4 programmable switch selects a forwarding link and performs load balancing NAT gateway forwarding according to the weighted hash load balancing strategy flow table, including: The P4 programmable switch receives a data packet from an access host and selects a forwarding link according to the weighted hash load balancing strategy flow table; Delivering the data packet to the corresponding NAT gateway exit of the P4 programmable switch according to the forwarding link; The NAT gateway egress of the P4 programmable switch performs source IP network address conversion on the data packet and sends the data packet to the peer server through the forwarding link. 4. According to the multi-path load balancing NAT gateway forwarding method based on P4 in claim 3, it is characterized in that, before the P4 programmable switch receives a data packet from an access host and selects a forwarding link based on the weighted hash load balancing strategy flow table, it also includes: After the access host is connected to the LAN port of the P4 programmable switch, the SDN controller automatically allocates an IP address to the access host through the DHCP dynamic host configuration protocol. 5. The multi-path load balancing NAT gateway forwarding method based on P4 according to claim 3 is characterized in that after the NAT gateway outlet of the P4 programmable switch performs source IP network address conversion on the data packet and sends the data packet to the peer server through the forwarding link, it also includes: After receiving the reply packet from the peer server, the NAT gateway exit of the P4 programmable switch converts the destination IP network address of the reply packet and sends it to the access host. 6. The multi-path load balancing NAT gateway forwarding method based on P4 according to claim 1, characterized in that the method further comprises: The SDN controller regenerates and sends the weighted hash load balancing strategy flow table to the P4 programmable switch in each cycle of sending a detection packet. 7. A multi-path load balancing NAT gateway forwarding system based on P4, characterized in that the system comprises: an SDN controller and a P4 programmable switch; The SDN controller is used to obtain a weighted hash load balancing strategy flow table according to the bandwidth-delay product, and send the weighted hash load balancing strategy flow table to the P4 programmable switch; The P4 programmable switch is used to select a forwarding link according to the weighted hash load balancing policy flow table and perform load balancing NAT gateway forwarding; The SDN controller is specifically used for: Periodically send a probe packet to each link to get a reply packet; According to the returned packet, the bandwidth Bandwidth and delay Delay of each link are obtained; According to the bandwidth Bandwidth and delay Delay of each link, a bandwidth-delay product BDP=Bandwidth×Delay of each link is obtained; According to the proportion of the bandwidth delay product BDP, a hash load balancing weight of each link is obtained; According to the hash load balancing weight of each link, the weighted hash load balancing strategy flow table is obtained; The weighted hash load balancing strategy flow table is sent to the P4 programmable switch. 8. The multi-path load balancing NAT gateway forwarding system based on P4 according to claim 7, characterized in that the P4 programmable switch is specifically used for: Receive a data packet from an access host and select a forwarding link according to the weighted hash load balancing strategy flow table; Delivering the data packet to the corresponding NAT gateway exit of the P4 programmable switch according to the forwarding link; The NAT gateway egress of the P4 programmable switch performs source IP network address conversion on the data packet and sends the data packet to the peer server through the forwarding link. 9. The multi-path load balancing NAT gateway forwarding system based on P4 according to claim 7, characterized in that the SDN controller is also used for: In each cycle of sending a detection packet, the weighted hash load balancing strategy flow table is regenerated and sent to the P4 programmable switch. 10. A processing device, characterized in that the processing device includes a memory, a processor, and a P4-based multi-path load balancing NAT gateway forwarding program stored in the memory and executable on the processor, and when the processor executes the P4-based multi-path load balancing NAT gateway forwarding program, the steps of the P4-based multi-path load balancing NAT gateway forwarding method as described in any one of claims 1-6 are implemented. 11. A storage medium, characterized in that the storage medium stores one or more programs, and the one or more programs can be executed by one or more processors to implement the steps of a multi-path load balancing NAT gateway forwarding method based on P4 as described in any one of claims 1-6 above.