Routers are key devices for connecting between networks. As a hub for interconnecting different networks, the router system forms the backbone of the TCP/IP based Internet, which can be said to be the "hub" of the entire network architecture.
4G CAT6 CPE With the gradual popularization of network applications, more and more enterprise networks are connected to the Internet. For most current networks, whether it is to achieve network interconnection or access the Internet, routers are indispensable. Due to the importance of routers, their management has become an important part of the daily work of network administrators, and the analysis and troubleshooting of router faults is also one of the most troublesome problems for many network administrators.
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Composition of routers
Currently, common routers can be divided into fixed port and modular structures in terms of structure. Fixed ports are usually adopted by some low-end routers, and the number and type of ports in these routers are already fixed. Usually, the number of ports is relatively small, and the processing capacity of routers is relatively low. This type of router has a low price and is more suitable for use in smaller networks, such as branch offices of small or medium-sized companies. Modular structures are generally adopted by mid to high-end routers. It usually reserves slots on the chassis, and users can choose different types of interface cards according to their needs. In high-end routers, the processor is also installed on the board and can be inserted into the slot of the chassis. This type of board is generally called the engine, and in the chassis, except for the power supply and fan, there is only a backplane for switching. In this way, users can not only choose interface cards, but also choose different engines for routers to customize routers with different processing capabilities.
5G CPE Regardless of the physical structure of the router, the logical structure of the router is usually similar, which is what is of concern when maintaining and configuring the router. Here are some parts related to this:
processor
The brain of the router. Similar to the function of a computer's CPU, it mainly completes the control function of the entire device.
DRAM
Dynamic memory. Equivalent to memory in a PC. The location where the code and data are stored during the operation of the router. Once a power outage or system restart occurs, all content will be lost.
BootROM
read-only memory. The content of this memory is programmed at the factory and mainly consists of some basic startup code. The content inside cannot be rewritten after leaving the factory.
NVRAM
A type of electrically erasable memory. The speed of writing data inside is relatively slow, but after a power outage, the content inside will not be lost and can be permanently saved. Usually storing system software, there is no need to write data to it during normal use. When necessary (such as system software upgrades), the data inside can also be updated.
Flash
Similar to NVRAM, it is also a non volatile memory, but it is typically used to store configuration files.
systems software
System software is the software platform for router operation (referred to as IOS in CISCO products). Although it does not have a specific physical form, it plays a crucial role in the operation of the entire router system. Many problems are related to it.
The above provides a brief introduction to the relevant parts of the router. A correct understanding of the functions of each part can help us understand the working principle of the router, quickly and effectively determine the scope of the fault, and reduce blindness.
Classification of common faults in routers
There are generally two types of faults that occur in routers: hard faults and soft faults. The classification method here does not have strict standards, it is only for convenience, and in practice, it should be analyzed on a case by case basis.
Hard fault
We categorize the situation where there are problems with the components of the router itself into this category. Common hard faults typically manifest in hardware. There are usually several types:
The system cannot power up normally
When the power switch of the router is turned on, the power light on the front panel of the router does not light up and the fan does not turn. At this point, it is important to focus on checking the power system. Check if the power socket has power and if the voltage is within the specified range. If the power supply is normal, the power cord should be checked for integrity and secure contact. If necessary, it can be replaced. If it still does not work, it can be determined that the problem should be on the power supply of the router. You can check if the power fuse of the router is intact, and if it burns, it should be replaced. If it still doesn't work, I have to send it for repair.
Component damage
This type of situation is a common type of hardware failure. The components here are often interface cards. This is manifested as when the problematic component is inserted into the router, other parts of the system are functioning normally, but the faulty component cannot be correctly identified. This is often because the component itself has a problem. There is also a situation where components can be correctly identified, but after configuration is completed (ensuring correct configuration), the interface cannot function properly, often due to physical faults. To confirm the above two situations, it is best to replace the suspected problematic component with a good component of the same model to confirm whether the problem exists.
System software damage
This type of fault seems to be classified as a software fault, but since it is often a problem with the router itself and is closely related to hardware, we may consider categorizing it here. Taking Cisco's router as an example, if the router always enters the RMAN state after powering on, it often indicates a problem with the system software IOS. In this case, it is advisable to rewrite the IOS.
other
What needs to be mentioned here are some situations where when upgrading system software, we may find that the system cannot complete the upgrade no matter what. At this time, it is advisable to check whether the size of the software you want to upgrade exceeds the NVRAM capacity of your router. If it exceeds the limit, you will never be able to upgrade. At this point, you should first expand the capacity of NVRAM and then upgrade the system software. This issue is easily overlooked.
Soft fault
Function cannot be implemented
Sometimes, you need to make certain specific configurations (such as NAT). You repeatedly check and confirm that the configuration is correct, but the corresponding function cannot be implemented. At this time, don't worry about suspecting that there is a problem with the device. It is best to first look for the version number of the system software and find the relevant instructions to see if the version of software you are using supports this function. Because the system software of routers often comes in many versions, each version supports different functions. If your current software version does not support this feature, you should find the corresponding software and upgrade first.
There are problems with network planning
Sometimes, your configuration seems to be fine, but the router just doesn't work properly or is unstable, and there are always some inexplicable problems. At this point, it's better not to rush back and forth with debugging. Instead, take a look at your network plan and see if there are any issues with it. For example, whether there are reused network segments, whether the calculation of network masks is correct, and so on, often the problem is solved easily.
Configuration issues
This type of problem is the most common, as there are indeed issues with your configuration. For example, if the parameters of the routers at both ends of the line do not match or are incorrect, this situation can always be solved by careful and meticulous search. I won't go into further detail here.
