The wide application of computer network has brought a lot of convenience to people, but the subsequent network failures have also brought a lot of trouble, and sometimes even brought huge economic losses. Below, I searched and sorted out the network fault diagnosis technology for everyone. Welcome to reading. I hope it helps you! For more information, please continue to pay attention to our fresh graduates training network!
With the development of modern science and technology, the integration of equipment is getting higher and higher, and the network carrying information has become an indispensable part of people's lives. However, some hardware failures often occur in the network operation, which makes the daily work unable to proceed normally. Diagnosing and eliminating network faults has become an important work in network management. In order to find network faults in time, locate them accurately and eliminate them, you must master a lot of professional knowledge and rich experience.
I. Research background
In the past decades, the scale of computer networks has experienced explosive growth. The application of network has penetrated into every corner of people's life and work, and has become an essential infrastructure. With the increasing dependence on the network, people also put forward higher requirements for the reliability of the network: ① a stable, efficient and safe network environment; (2) when the network fails, the cause of the failure can be found in time and repaired. It can be seen that network fault diagnosis is of great significance for maintaining the health of the network. However, in today's network environment, network fault diagnosis has encountered unprecedented difficulties, mainly in the following aspects;
1. Computer networks have made great progress in scale, network complexity and business diversity. The fault relationship of large-scale networks is complex, and the corresponding relationship between fault causes and fault phenomena is vague, which greatly improves the difficulty of fault diagnosis.
2. The complexity of network equipment also increases the difficulty of fault diagnosis. The complexity of network equipment has two meanings: first, new network equipment is constantly introduced, with more and more functions and more complexity; Second, there are a large number of equipment providers, and product specifications and standards are not uniform;
Second, the network architecture
Network architecture includes protocols, entities and interfaces.
To realize communication in computer networks, we must rely on network protocols. In the 1970s, the products of major computer manufacturers all had their own network communication protocols. However, it is difficult to connect computer systems produced by different manufacturers. In order to realize data communication between computer systems produced by different manufacturers and between different networks, the International Organization for Standardization (ISO) or OSI/RM is also called ISO/OSI, and this system is called an open system.
Physical layer is the lowest layer of OSI/RM, including: 1. Physical characteristics of communication interface and transmission medium; 2. The data exchange unit of the physical layer is binary bits; 3. Synchronization of bits; 4. Connection of lines; 5. Physical topology; 6. Mode of transmission.
The data link layer is the second layer of OSI/RM, including framing, physical address addressing, flow control, error control and interface control.
Network layer is the highest layer of computer communication subnet, including logical address addressing, routing function, flow control and congestion control.
Other levels: transport layer, session layer, presentation layer and application layer.
Computers also have TCP/IP architecture, that is, transmission control protocol/Internet protocol. TCP/IP includes the hierarchy and protocol set of TCP/IP.
Third, the principles of network fault diagnosis
Network failures are extremely common and the types of failures are very complicated. If we classify and find the common faults of network faults, we can undoubtedly find the root of the faults quickly and accurately and solve the network faults. Generally, it can be divided into two categories: physical failure and logical failure.
Physical faults generally refer to physical problems or hardware problems of lines or equipment.
1. Line failure
In daily network maintenance, the incidence of line faults is quite high, accounting for about 70% of the faults. Line faults usually include line damage and serious electromagnetic interference.
2. Port failure
Port failures usually include loose plug and physical failure of the port itself.
3. Hub or router failure
Hub or router failure here refers to physical damage, which can not work, leading to network failure.
4. Host physical failure
Network card failure, the author also classifies it as a physical failure of the host, because most network cards are installed in the host, and the configuration and communication are completed by the host, which can be regarded as a network terminal. This kind of fault usually includes network card looseness, network card physical fault, host network card slot fault and host itself fault.
Host resources are stolen, and the host does not control services such as finger, RPC and rlogin. Attackers can attack the host through the normal services or vulnerabilities of these processes, and even get administrator rights, and then have the right to copy and modify all the contents of the disk at will. It should also be noted that you should not easily enjoy the local hard disk, because this will lead to malicious attackers illegally using the resources of the host.
Four, the main technology of network fault diagnosis
The research and application of wireless sensor networks in the military can be traced back to the Cold War, when the United States established a submarine sonar monitoring system to monitor the relevant information of the former Soviet nuclear submarines, and then established a radar air defense network.
Wireless sensor networks are dense, low-cost and randomly distributed. Self-organization and fault tolerance make the whole system not collapse because some nodes are damaged in malicious attacks, which is incomparable to traditional sensor technology. It is precisely this that makes the sensor network very suitable for the harsh battlefield environment [6], which mainly includes reconnaissance of the enemy, monitoring of troops and equipment, and judgment of nuclear and biological attacks. , and can be used in many ways.
In wireless sensor networks, according to a certain election mechanism, some nodes are selected as backbone nodes, and the peripheral nodes belong to the management of backbone nodes, and then the backbone nodes are responsible for building a connected network. This algorithm divides the whole network into connected regions, which is called clustering algorithm or clustering algorithm. The backbone node is the cluster head, and the common node is the node in the cluster. Hierarchical clustering algorithm usually selects cluster head nodes periodically to balance the energy consumption of nodes in the network.
Wireless sensor network is a special wireless self-organizing network, which is a network application system composed of a large number of intelligent sensor nodes densely deployed in the monitoring area. Its rapid and convenient deployment and complete monitoring capability make it widely used in military, industrial process control, medical care and environmental monitoring. In wireless sensor networks, the energy of nodes is very limited, and there is generally no energy supplement, so how to use energy efficiently to maximize the network life cycle has become the primary challenge for sensor networks.
Research prospect of verb (abbreviation of verb)
The research on topology control of wireless sensor networks is the core to promote the further development of WSN, and the optimization of energy management strategy involves the design of CMOS circuits from the physical layer to the upper layer or even below the physical layer.
Network topology is an important platform for upper layer protocols to run, and its good structure can improve the efficiency of routing protocols and MAC protocols, which is helpful to experiment with the primary design goal of WSN.
From the analysis of the full text, it can be seen that the inherent contradiction of topology control can be summarized as the need to achieve global data transmission in a balanced way with as little energy consumption as possible, and on this basis, the cost of the algorithm itself, the unpredictability of traffic in the real environment and the influence of the network environment are considered.
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