In order to manage the managed program (agent), the manager needs to know the information model in the managed program (in fact, it is the information model of the managed object contained in the agent). In order to transmit this information, people must agree on a network protocol between the manager and the managed. We know that different platforms have different encodings for integers and characters. In order to enable applications under different platforms to read each other's data, a unified and unambiguous data description grammar and coding format must be specified. Therefore, ITU has stipulated the syntax of information model definition (GDMO), the protocol of OSI application layer (CMIP) and standard data description language (ASN. 1, abstract syntax symbol 1).
GDMO grammar is mainly used to describe various concrete and abstract resources that need to be managed in various networks. This syntax is needed to describe the information model of equipment in general manufacturers' equipment, which is convenient for users or other manufacturers to manage equipment. The lower protocol of CMIP generally uses OSI protocol stack, which is mainly used to realize various operations on objects defined by GDMO, such as creating and deleting object instances, reading and writing attributes, and so on. Due to different hardware and data formats (coding format, word length, internal addressing boundary of the structure, etc. On the software platform, TMN managers and managed persons must describe the received data through a unified data description grammar ASN. 1 to ensure the correct analysis of the received data and take out the correct data content.
ASN. 1 is not only a data description language, but also provides the same data coding format for both parties, such as BER (Basic Coding Rule). Between the supervisor and the managed program, the information model is defined by standard GDMO, the interactive data is defined by ASN. 1, and the interactive operation is realized by CMIP. After realizing these three points, we can think that the equipment meets the Q3 reference point standard between TMN functional modules. Of course, ITU also stipulates other interfaces, such as Qx, X and so on. These interfaces can be considered to serve Q3.
Second, the development of network management
In fact, the network management has long existed. Because in a broad sense, any system needs management, but according to the size and complexity of the system, the importance of management in the system is also heavy or light. The network is of course a system. Telecom networks dating back to the end of 19 have their own corresponding management "system"-telephone operators. He is the administrator of the whole telephone network system, although the content he can manage is very limited. The management of computer network can be said to be accompanied by the emergence of —ARPANET, 1969, the first computer network in the world. At that time, ARPANET had a corresponding management system. Some later network structures, such as IBM's SNA, DEC's DNA and Apple's AppleTalk, also have corresponding management systems. However, although network management has existed for a long time, it has not received due attention. This is because the network at that time was small in scale and low in complexity, and a simple private network management system could meet the needs of the normal work of the network, so there was little research on it. However, with the development of the network and the increase of scale and complexity, the previous network management technology can no longer adapt to the rapid development of the network. Especially in the past, the network management system was often a special system developed by manufacturers in their own network systems, and it was difficult to manage other manufacturers' network systems and communication equipment software. This situation is not suitable for the development trend of heterogeneous network interconnection. The appearance and development of the Internet in the early 1980s made people more aware of this.
R&D personnel quickly launched the research on network management, and put forward a variety of network management schemes, including HEMS (Advanced Entity Management System) and SGMP (Simple Gateway Monitoring Protocol). Cmis/cmip (common management information service/protocol), netview, lanmanager, etc. By the end of 1987, IAB(Internet Activities Board), the core management organization of the Internet, realized that it was necessary to choose among many network management schemes in order to focus on network management. IAB should choose a management scheme suitable for TCP/IP networks, especially the Internet. At the meeting of 1988 in March, IAB formulated the development strategy of Internet management, that is, adopting SGMP as a short-term Internet management solution and turning to CMIS/CMIP in due course. Among them, SGMP is a network management tool developed and applied on NYSERNET and SURANET, while CMIS/CMIP is a network management standard jointly formulated by ISO and CCITT in the mid-1980s. At the same time, IAB has also set up corresponding working groups to make appropriate modifications to these schemes to make them more suitable for Internet management.
These working groups then introduced SNMP (Simple Network Management Protocol) (1988) and CMOT(TCP/IP/CMIS over TCP/IP) (1989). But the actual development is not as planned by IAB. SNMP has been widely used and supported since it came out, but CMIS/CMIP is difficult to realize because of its complexity and high implementation cost. When ISO constantly modifies CMIP/CMIS to make it mature, SNMP has been tested and developed in practical application environment. 1990, IETF officially released SNMP in RFC 1 157,1April 993, and released SNMP v2(RFC 144 1). When the ISO network management standard finally matured, SNMP has been supported by hundreds of manufacturers, including IBM, HP, Fujitsu, SunSoft and other big companies and manufacturers. At present, SNMP has become a de facto industrial standard in the field of network management, and has been widely supported and applied. Most network management systems and platforms are based on SNMP.
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Due to the need of practical application, there are more and more researches on network management, which has become a global hot topic involving communication and computer fields. Cnom (Network Operation and Management Committee) under the IEEE Communication Society holds a seminar on network operation and management every two years from 1988. International federation for information processing (IFIP) also holds a seminar on integrated network management every two years from 1989. There is also an OSI Network Management Forum (OSI/NM FORUM), which is dedicated to discussing related issues of network management. In recent years, some manufacturers and organizations have launched their own network management solutions. The DME (Distributed Management Environment) ratio of the network management forum OMNIPoint and the Open Software Foundation (OSF) is more influential. In addition, major computer and network communication vendors have launched their own network management systems, such as HP's OpenView, IBM's NetView series, Fujitsu's NetWalker and SunSo ft's Sunnet Manager. They have been applied in various practical application environments and have had a considerable impact.
In recent years, the Internet has developed rapidly in China, especially in some large and medium-sized enterprises, banking and financial departments, post and telecommunications industries and other fields. But network management is only the initial stage. Because network management system is very important for the efficient operation of a network system, it is urgent to popularize the research and application of network management system in China. Our view is that we should adopt the combination of introduction and independent development in application. On the one hand, the research and application of network management in China has just started, and there is a certain gap with the advanced level abroad, so it is not realistic to develop it entirely by itself; On the other hand, it is not good to rely solely on foreign products. Foreign network management products may not be suitable for China's network application environment, which is also unfavorable for our own network management research. In research, we should try our best to follow the advanced foreign technology and carry out our own research.
Third, the function of network management.
ISO defines five functions of network management in ISO/IEC 7498-4 document, which is widely accepted. These five functions are:
(1) fault management
Fault management is one of the most basic functions in network management. Users want to have a reliable computer network. When a component in the network fails, the network administrator must quickly find the fault and eliminate it in time. It is usually impossible to isolate faults quickly, because the causes of network faults are usually quite complicated, especially when the faults are caused by multiple networks. In this case, the network is usually repaired first, and then the cause of network failure is analyzed. It is very important to analyze the cause of the failure to prevent the recurrence of similar failures. Network fault management includes fault detection, isolation and correction, and should include the following typical functions:
Maintain and check the error log.
. Accept the error detection report and respond.
Track and identify errors.
Perform diagnostic tests.
Correct the error
Network fault detection is based on monitoring the status of network components. Simple faults that are not serious are usually recorded in the error log without special handling; More serious failures need to be notified to the network administrator, which is called "alarm". The chief network manager handles the alarm and eliminates the fault according to the relevant information. When the fault is complex, the network administrator should be able to perform some diagnostic tests to determine the cause of the fault.
(2) Accounting management.
Billing management records the use of network resources, with the purpose of controlling and monitoring the cost and expenses of network operation. It is especially important for some public commercial networks. It can estimate the expenses and costs that users may need to use network resources, and the resources that have been used. The network administrator can also stipulate the maximum fee that users can use to control users from occupying and using network resources too much. This also improves the efficiency of the network on the other hand. In addition, when users need to use resources in multiple networks for communication purposes, billing management should be able to calculate the total cost.
(3) Configuration management
Configuration management is also important. It initializes the network and configures it to provide network services. Configuration management is a set of related functions necessary to identify, define, control and monitor the objects that make up a communication network, so as to realize specific functions or optimize network performance.
This includes:
. Set the related parameters of routing operation in open system.
Manage managed objects and managed object group names.
Initializes or closes a managed object.
Collect relevant information about the current state of the system as needed.
Get information about important changes in the system.
. Change the configuration of the system.
(4) Performance management.
Performance management evaluates system performance, such as the running state of system resources and communication efficiency. Its functions include monitoring and analyzing the performance mechanism of the managed network and the services it provides. The results of performance analysis can trigger the diagnostic test process or reconfigure the network to maintain the performance of the network. Performance management collects and analyzes data information about the current situation of the managed network, and maintains and analyzes performance logs. Some typical functions include:
Collect statistical information
Maintain and check the system status log.
Determine the performance of the system under natural and artificial conditions
. Change the system operation mode and manage the system performance.
(5) Safety management.
Security has always been one of the weak links in the network, and users have high requirements for network security, so network security management is very important. There are several major security problems in the network: the privacy of network data (to protect network data from being illegally obtained by intruders), authentication (to prevent intruders from sending wrong information on the network) and access control (to control access to network resources). Accordingly, in addition to maintaining and checking security logs, network security management should also include authorization mechanism, access control, encryption and encryption keyword management. Including:
Create, delete and control security services and mechanisms.
Distribution of safety-related information
Report of safety-related events