Due to the development of multimedia and other applications in the network, and the continuous adoption of new technologies such as ATM and Fast Ethernet, the bandwidth and speed of the network are rapidly increasing, and traditional wifi routers can no longer meet people's performance requirements for wifi routers. Because the design and implementation of packet forwarding of traditional wifi routers are based on software, the processing of packets in the forwarding process has to go through many links, and the forwarding process is complicated, which makes the rate of packet forwarding relatively slow.
1. New generation wifi routers
Since the wifi router is a key device for network interconnection and a "gateway" for the network to communicate with other networks, it has high requirements for its security. Therefore, various additional security measures in the wifi router increase the burden on the CPU. This makes the wifi router a "bottleneck" on the entire Internet.
Traditional wifi routers perform a series of complex operations when forwarding each packet, including route lookup, access control table matching, address resolution, priority management and other additional operations. This series of operations greatly affects the performance and efficiency of the wifi router, reduces the packet forwarding rate and forwarding throughput, and increases the burden on the CPU. However, the correlation between the packets before and after the wifi router is very large, and the packets with the same destination address and source address often arrive continuously, which provides the possibility and basis for the fast forwarding of the packets. New-generation routers, such as IP Switch and Tag Switch, use this design idea to implement fast forwarding with hardware, which greatly improves the performance and efficiency of wifi routers.
Next-generation wifi routers use forwarding caches to simplify forwarding of packets. In the fast forwarding process, only the first few packets of a group of packets with the same destination address and source address need to be traditionally routed and forwarded, and the destination address, source address and next gateway address ( next router address) in the forwarding cache. When the subsequent packet is to be forwarded, first check the forwarding cache. If the destination address and source address of the packet match those in the forwarding cache, it will be forwarded directly according to the next gateway address in the forwarding cache, without going through the traditional The complex operation of the wifi router greatly reduces the burden of the wifi router and achieves the goal of improving the throughput of the wifi router.
1.1 Basic Concepts
Routing is the act of moving information from a source location to a destination location through an interconnected network. Generally speaking, in the routing process, information will go through at least one or more intermediate nodes. Often, people compare routing and switching, mainly because to the average user, the two perform exactly the same function. In fact, the main difference between routing and switching is that switching occurs at the second layer (the data link layer) of the OSI reference model, while routing occurs at the third layer, the network layer. This difference determines that routing and switching need to use different control information in the process of moving information, so the two implement their respective functions in different ways.
As early as 40 years ago, there have been discussions on routing technology, but it was not until the 1980s that routing technology gradually entered commercial applications. The reason why routing technology was not widely used at the beginning of its existence was mainly because the network structure before the 1980s was very simple, and routing technology was useless. It was not until the last decade or so that large-scale Internet gradually became popular, which provided a good foundation and platform for the development of routing technology.
A wifi router is the main node device of the Internet. The wifi router determines the forwarding of data through routing. The forwarding strategy is called routing (rouTIng), which is also the origin of the router name (router, forwarder). As the interconnection hub between different networks, the wifi router system constitutes the main vein of the Internet based on TCP/IP. It can also be said that the wifi router constitutes the skeleton of the Internet. Its processing speed is one of the main bottlenecks of network communication, and its reliability directly affects the quality of network interconnection. Therefore, in the field of campus network, regional network, and even the entire Internet research field, wifi router technology has always been in the core position, and its development process and direction have become a microcosm of the entire Internet research. At the current time when my country's network infrastructure and information construction are in the ascendant, this paper discusses the role, status and development direction of routers in interconnected networks, for domestic network technology research, network construction, and to clarify routers and network interconnection in the network market. The various plausible concepts of , all have important meanings.
1.2 Principle
A wifi router is used to connect multiple logically separated networks. The so-called logical network represents a single network or a subnet. When data is transferred from one subnet to another, it can be done through routers. Therefore, the wifi router has the function of judging the network address and selecting the path. It can establish flexible connections in a multi-network interconnection environment, and can connect various subnets with completely different data packets and media access methods. The wifi router only accepts source stations or other wifi Router information, which is an interconnected device at the network layer. It does not care about the hardware devices used by each subnet, but requires running software that conforms to the network layer protocol. Routers are divided into local wifi routers and remote routers. Local wifi routers are used to connect network transmission media, such as optical fibers, coaxial cables, and twisted pair cables; remote wifi routers are used to connect remote transmission media and require corresponding equipment, such as telephone lines. Equipped with a modem, wireless must pass through a wireless receiver and transmitter.
WiFi router works as follows:
1.2.1 The workstation A sends the address 12.0.0.5 of the workstation B together with the data information to the wifi router 1 in the form of a data frame.
1.2.2 After wifi router 1 receives the data frame of workstation A, it first takes out the address 12.0.0.5 from the header, and calculates the best path to workstation B according to the path table: R1->R2->R5->B; and Send the data frame to wifi router 2.
1.2.3 wifi Router 2 repeats the work of wifi Router 1 and forwards the data frame to wifi Router 5.
1.2.4 wifi Router 5 also takes out the destination address and finds that 12.0.0.5 is on the network segment connected to the wifi router, so the data frame is directly handed over to workstation B.
1.2.5 Workstation B receives the data frame from Workstation A, and a communication process ends.
In fact, in addition to the above-mentioned main function of routing, the wifi router also has the function of network flow control. Some wifi routers only support a single protocol, but most wifi routers can support the transmission of multiple protocols, that is, multi-protocol routers. Since each protocol has its own rules, it is bound to reduce the performance of the wifi router to complete the algorithms of multiple protocols in one router. Therefore, we believe that the performance of wifi routers supporting multiple protocols is relatively low. When purchasing a wifi router, users need to choose the wifi router with the network protocol they need according to their actual situation.
In recent years, switching router products have appeared. In essence, it is not a new technology, but in order to improve the communication ability, the principle of the switch is combined into the wifi router to make the data transmission ability faster and better.
2. WiFi router function
One function of the wifi router is to connect different networks, and the other function is to select the line for information transmission. Choosing a smooth and fast shortcut can greatly improve the communication speed, reduce the communication load of the network system, save network system resources, and improve the smooth rate of the network system, so that the network system can play a greater role.
From the point of view of filtering network traffic, wifi routers function very similarly to switches and bridges. But unlike the switch that works at the physical layer of the network and divides the network segment physically, the router uses a special software protocol to logically divide the entire network. For example, a wifi router that supports the IP protocol can divide the network into multiple subnet segments, and only network traffic directed to a specific IP address can pass through the router. For each received packet, the wifi router recalculates its checksum value and writes a new physical address. Therefore, using a wifi router to forward and filter data tends to be slower than a switch that only looks at the physical address of a packet. However, for those complex networks, the use of routers can improve the overall efficiency of the network. Another obvious advantage of wifi routers is that they can automatically filter network broadcasts. In general, the entire installation process of adding a wifi router to a network is much more complicated than a plug-and-play switch.
Generally speaking, the interconnection of heterogeneous networks and the interconnection of multiple subnets should be completed by wifi routers.
The main job of a wifi router is to find an optimal transmission path for each data frame passing through the wifi router, and to efficiently transmit the data to the destination site. It can be seen that the strategy of selecting the best path, that is, the routing algorithm, is the key to the wifi router. In order to complete this work, the relevant data of various transmission paths, the RouTIng Table, is stored in the wifi router for use in routing. The path table stores the information of the subnet flag, the number of wifi routers on the network, and the name of the next wifi router. The path table can be fixed by the system administrator, or dynamically modified by the system, automatically adjusted by the wifi router, or controlled by the host.
2.1 Static Path Table
A fixed path table set in advance by a system administrator is called a static path table, which is generally preset according to the network configuration during system installation, and will not change with future network structure changes.
2.2 Dynamic Path Table
Dynamic (Dynamic) routing table is the routing table automatically adjusted by the wifi router according to the operation of the network system. The wifi router automatically learns and memorizes the network operation according to the functions provided by the Routing Protocol, and automatically calculates the best path for data transmission when needed.
