Most modern types of network equipment support SNMP. This standard is considered very simple in structure. Its implementation in the network infrastructure of modern companies is not difficult. Computer control through the appropriate protocol can be implemented using a wide range of software solutions. What are the main features of SNMP? How is the appropriate protocol used in practice?
What is SNMP?
To begin, we will study the basic information about the technology under consideration. What is SNMP? This abbreviation stands for Simple Network Management Protocol, and means "Simple Network Management Protocol." This standard is one of the most common that are used to control various devices in IP networks that operate on the basis of the TCP / IP architecture. For example, routers, switches, workstations, network printers.
The protocol under consideration is most often used in cases where the infrastructure involves the monitoring of devices that are connected to the network, in order to fulfill the conditions specified by the administrator. The structure of information, the turnover of which is carried out within the framework of the SNMP protocol, includes, in particular, those that are presented in the form of variables by which it is possible to describe the configuration of the control object that is in the network system. Through control applications, the corresponding variables can be requested, and in some cases set.
SNMP Features
The protocol under consideration allows network administrators to configure certain devices using the main server without resorting to special programs whose functionality is designed to monitor various network processes. Using the protocol in question, it is possible to carry out not only the management (SNMP in this sense is a unique tool) of certain procedures during the administration of processes in the network, but, in particular, also monitor the performance of the infrastructure and identify problems that arise in her, monitor the use of network resources.
Now consider what key components form the infrastructure of networks based on SMTP.
SNMP: core components
SNMP is a protocol that involves the use of several network components. The main ones include:
- managed object - a computer or application to which it sends certain commands using the protocol in question, the network administrator;
- MIB database;
- agent application;
- program manager;
- a system for ensuring network interaction.
The managed object can not only receive commands from the administrator, but also send them in accordance with the specified parameters. Data from the object is transferred to the manager program, which interprets them according to the established algorithms. In turn, an agent application operates on a managed device. It collects information on the corresponding device and, if necessary, translates it in a format adapted to the specifics of the SNMP protocol.
The network communication support system allows the administrator to work with several manager programs in order to control the functioning of the infrastructure. In this case, several types of software of the corresponding type can be installed on networks.
The most important, perhaps the key element of the SNMP protocol is the MIB, or control information base. Its purpose is to describe the data structure that is exchanged in the process of managing devices. In fact, the corresponding database allows you to place information that is used to control the device directly on it, whether it is a modem, server, or, for example, a network card. SNMP is a universal protocol, and in many ways its functionality can be implemented thanks, first of all, to the capabilities of the MIB database.
Devices compatible with this technology contain both standard variables and those that characterize the features of an individual device. The main elements of this database are OID type identifiers. They allow you to set variables that are read or defined using the SMNP protocol.
The agent application, which is a component of the SMNP network infrastructure, usually receives requests using port 161. In turn, the manager program can use any ports available on the network. In this case, this type of software usually receives notifications on port 162.
Consider the main tools used by administrators who use the SNMP protocol in their work, in more detail. Among them is a program manager.
SNMP Manager Program: Key Features
This type of software allows, thanks to the capabilities of the protocol in question, to manage groups of various devices within the network infrastructure. The program in question can function subject to preliminary installation on devices that are controlled through its interfaces, a special agent application, which we mentioned above. It sends the necessary data to the administrator server using the SNMP protocol. In turn, on the side of the main PC, the manager program in question operates, which processes information received from managed devices.
What software is used to manage the network via SNMP?
What specific programs can be used as managers? In principle, there are solutions adapted for the implementation of the SNMP protocol in various operating systems - Windows, Solaris. If we talk about software for Windows, then among the popular ones that work in this OS and use SNMP is the package released by Castle Rock Computing. In turn, another effective solution has been developed for Solaris - Sun NetManager. Both options can be used to build an efficient SNMP-based network card. In addition, they allow direct communication with the MIB.
Within the corresponding interfaces, it is possible to control routers of various brands that support the SNMP protocol, in particular, Cisco. As a rule, modern manufacturers of network devices issue documentation on the MIB of a device that reflects the ability to manage the corresponding infrastructure components within the network.
Another popular solution for managing network devices is Zabbix. SNMP is a protocol that this program also uses. The corresponding solution has a large number of functions.
In terms of the use of SNMP, it, for example, allows for effective monitoring of network processes. SNMP data exchange is carried out through special messages. Consider their specifics in more detail.
Features of SNMP Messages
The main messages that the administrator server can initiate the exchange of via SNMP include commands such as:
- GetRequest;
- SetRequest;
- GetNextRequest;
- GetBulkRequest;
- Response
- Trap;
- InformRequest.
The essence of the 1st team is to send a request from the manager program to the agent application in order to obtain one or another value from a variable - one or from a list. In turn, the manager receives a response with certain values.
The specificity of the 2nd team is to send a message also from the manager program to the agent application, but in this case, in order to adjust the variable - one or from a list. The agent application accepts the changes and then sends the manager program new values for one or another variable.
The essence of the 3rd team is to send a request from the manager program to the agent application of certain commands in order to detect on the device all available variables, as well as the values that are set for them. In turn, the agent application returns a response that contains the value of one variable, as well as a link to the next, relative to its position in the list. The next request involves the transfer of data reflecting information on the next variable, as well as a link to the one that goes further in the queue. Further, the data turnover algorithm using the considered SNMP command is repeated.
The specificity of the 4th command is that in fact it is an upgraded version of the GetNextRequest message. It assumes that the agent application will transmit to the manager program a response containing data on several variables at the same time, starting with the one presented in the initial request.
The essence of the 5th command is to carry out the procedure for returning the associated variable, as well as the values from the agent application to the manager program, using the 4 types of messages discussed above. In this case, through the appropriate command between devices, error messages are exchanged.
The specificity of the 6th team is in the transfer of messages from the agent application without a preliminary request from the program manager. The structure of this message contains the current value of the variable. Note that the recipient of the command in this case is determined by means of special configurations within the framework of the MIB.
The essence of the 7th team is that it, in fact, corresponds to the notification of sending a message from the manager program to the agent application and vice versa. Its use is due to the fact that in a network infrastructure certain messages in some cases may not be delivered correctly. The InformRequest team, in fact, confirms the fact of the successful transfer of the command from one device to another.
Correct SNMP configuration in many cases requires the administrator to pay more attention to checking the functionality of the MIB. Consider what its features are.
MIB: features of the functioning of the base
The key procedure in the framework of the functioning of the MIB is the addressing of variables. It is carried out taking into account the structure of the considered component of the SNMP protocol. The MIB looks like a tree diagram consisting of several elements, each of which has a special identifier.
The variable name within the MIB reflects the address to it, starting from the root directory. The structure of a variable can contain a variety of information, for example, about the device’s operating time. In the tree structure, MIBs can be present as standard branches that are supported by most devices, or those added by the device manufacturer or by the organization in which the computer network infrastructure is implemented. The main thing in this case is to correctly place the corresponding sets of variables.
So, if they are introduced into the MIB structure temporarily, then it makes sense to place them in the experimental section. Immediately before approving the database structure, a separate number should be assigned to the set of variables. To do this, use the private-enterprises section. This will allow engineers or network administrators, whose competence is SNMP monitoring and solving other tasks to ensure the functioning of the infrastructure, to open a new branch in the MIB structure in order to place variables only from their company.
SMNP History
It will be interesting to learn about the history of SNMP development. The main software environment in which the SNMP protocol is currently used is Windows. However, its development was initiated back in 1988 - long before the Microsoft operating system, presented in familiar interfaces, began to conquer markets. In fact, SNMP was originally developed for UNIX - a family of operating systems designed to solve a wide range of tasks to ensure the functionality of various computer networks. Although, of course, by that time, many experts saw the potential of Windows, and it is possible that the development of a universal network protocol was largely predetermined by the fact that the new operating system could become more popular.
Of course, there was another factor that played an important role in speeding up work on SNMP - the Web. Already then the first online services appeared, and it was clear to experts that ahead was the active integration of network interfaces on a global scale.
One way or another, the largest manufacturers of network devices in 1988 decided that they needed to develop a universal set of tools designed to manage devices. By that time, companies released their own solutions for monitoring, as well as configuring devices. Unification was needed.
SNMP Development: Basic Instructions
In August 1988, network equipment makers came to a consensus. In the process of developing the new protocol, some existing concepts were applied. The specialists who conducted the collaboration identified 3 key documents: RFC 1065, 1066, and 1067. Subsequently, they were supplemented and new ones appeared - RFC 1155, 1156, and 1157. These sources were processed and in 1991 they were basis, the first version of SNMP was released.
So, RFC 1155 contained instructions defining:
- the structure in which management information should be reflected;
- What are the basic principles for applying syntax when defining names for variables.
RFC 1155 has been supplemented by the source RFC 1212 for, again, the syntax of variables. At the time of approval of the SMNP protocol, a number of new documents were developed, such as RFC 1213. It reflected a list of key variables by which the network infrastructure was to be configured.
The RFC 1157 source contained parameters necessary for:
- definitions of commands by which the server and the managed object could interact with each other;
- the implementation of the exchange of trap messages.
As soon as the SNMP protocol, adapter, network card, server were published and introduced - in principle, any device that would be part of the network infrastructure could become the object of control carried out as part of standard procedures. The introduction of SNMP has become the strongest growth factor in the global network equipment market. Also, thanks to standardization, it became possible to introduce new interfaces on the widest scale, such as, for example, Ethernet, FDDI.
Summary
So what is SNMP, we found out. This abbreviation corresponds to one of the key network protocols that are used to maintain the functionality of modern computer networks. This protocol involves the implementation between the various infrastructure elements - managing servers and managed devices, the exchange of standardized messages. In this case, an appeal is made to the MIB database of a device.
Through standardized messages within the SNMP protocol are implemented:
- requests for one or more MIB parameters;
- sequential reading of various values for various parameters, for example, tabular;
- setting specific values for one or more MIB variables;
- the device returns a response to a particular request from another device;
- sending notification messages about certain network processes.
MIB algorithms can be both general for all devices, and those that are prescribed by manufacturers for specific types of network equipment.
What is SNMP in terms of importance for the modern IT market? This technology is obviously among the most important, and in many cases has no alternative. And this despite its simplicity, which, however, was the result of many years of development and coordination of network standards with the participation of leading equipment manufacturers.
Network communications, within which the capabilities of the MIB protocol are used, involve the use of program managers, as well as agent applications. The first send various commands to the second, after which the device software performs certain algorithms. Data is also transferred according to established schemes from the agent application to the manager program.
Network computers can be managed from the main server. A special program, for example, Zabbix, can be involved for this. SNMP is a protocol supported by programs that can run on different operating systems. Initially, SNMP was developed for UNIX, but types of software were created that allowed it to be used in Windows, Sun Solaris.
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