In-depth explanation of Key Technologies in vro Technology

At present, China's vro technology is developing very rapidly. So I have studied the key technologies in the vro technology and shared them here. I hope they will be useful to you. The Internet is connected by routers. The router technology is the core device of the Internet or an IP network. The increasing bandwidth access has led to the increasing demand for router technologies.

When talking about the development of vro technology, we can't help but talk about the development of "embedded" devices. That's right. Generally speaking, vro technology is an embedded product. So what is an embedded device? As a matter of fact, embedded devices are constantly exploring every aspect of our daily lives. Generally speaking, an embedded device is a device or equipment that has a computer function but is not called a computer. It includes almost all the electrical equipment around us: PDA, mobile phone, set-top box, automobile, microwave oven, elevator, security system, vending machine, medical instrument, stereo audio, ATM, etc.

In more professional words, embedded devices are embedded devices that use microprocessor or microcontroller chip (MCU), peripheral circuits, and internal programs to implement specific functions. For example, 8-bit single-chip microcomputer, 32 ARM, and DSP chip all belong to the category of embedded core chip. The 8-bit MCU market has gradually stabilized, and 32-bit MPU represents the development direction of embedded technology and is accelerating development. In the 32-bit embedded microprocessor market, the ARM Kernel-based microprocessor is in an absolute leading position in the market, so it is particularly important to track the development trend of ARM technology.

Vro development is generally based on a 32-bit processor. Generally, low-end and Middle-end vrouters have multiple options for development configuration, for example, there are a variety of options, such as arm9-core chip + Wince operating system, arm7-core chip + uClinux operating system, DSP chip + Vxworks operating system. This article introduces common SOHO router technologies and selects the development mode of the ARM7 core chip + uClinux operating system. It provides a complete example to explain the router technology implementation process.

Why are we introducing SOHO router technology? What is a SOHO router? In the past, many families had more than one computer and needed to access the Internet to obtain information and send and receive emails. The number of computers for these small companies and home network users is generally small, and the network structure is not complex. Features and bandwidth requirements are not high. To improve network performance, share limited IP addresses, or save Internet access costs, these users urgently need cost-effective small routers. We call this small router a SOHO router. At present, the market is flooded with a large number of such low-end routers, which are very suitable for embedded systems due to the low cost of the chip series. At present, most SOHO router technologies on the market use the ARM7 series processor. However, with the development of technology, the vro technology of the dedicated Routing Chip of the ARM9.

We can simply understand the development of embedded devices as a three-tier model. The bottom layer is a hardware system consisting of a microcontroller chip and peripheral devices, for example, the ARM7TDMI chip used in the development of small SOHO router technology is the hardware basis for the implementation of device functions. To realize upper-layer applications, the support of the lowest-layer hardware is required. The middle layer is the operating system. For example, the uClinux operating system we select is the intermediate layer connecting the hardware part and the application. It can complete basic operations on the underlying hardware, it can also provide Runtime Environment Support for upper-layer applications. The upper layer is the application layer, which is the code part for implementing targeted applications, such as functional programs such as routing settings.

How vro works

To implement communication between nodes in the current network, you must first assign a unique IP address to each node. Router technology should have at least two network ports connected to the LAN or WAN subnet respectively. Each port must have a unique IP address and must be the same as the network number of the connected IP subnet. Different ports have different network numbers and correspond to different IP subnets. In this way, hosts in each subnet can send IP datagram requests to the vro through their own subnet IP addresses.

When the router receives an IP datagram, it must first judge the message and then proceed with further processing based on the result. If the datagram is valid or correct, the router forwards the message based on the destination IP address of the datagram. Otherwise, the packet is discarded. If the destination IP address of the datagram is directly connected to a sub-Network of the router, the router technology will forward the packet to the destination subnet through the corresponding interface; otherwise, it will be forwarded to the next Hop router. To complete the preceding operations, each vro must maintain a route table. Store the optimal paths for different destinations in the Routing table. This is the Routing Policy problem. The route table reflects the network topology. Generally, a table entry should contain the destination IP address of the datagram (usually the network address of the destination host) the IP address of the next hop router technology and the corresponding network interface. When the network topology changes, the route table should also be changed accordingly. Therefore, the router technology must be able to generate and update the route table.

The routing mechanism is actually how to find the route table and query the route table to decide which direction to forward data. In general, the router first searches for the matched host address. If not, then searches for the matched network address. Finally, searches for the default route. Once a matching table item is found, the router technology will send the data from the corresponding interface. After the router has the preceding elements, it can complete the data forwarding task. In addition, the router technology is not only responsible for forwarding IP packets, but also responsible for communicating with other router technologies to jointly determine Internet route selection and route table update and maintenance.