Simple Network Management Protocol perspective-from SNMPV1 to SNMPv3

Simple Network Management Protocol (SNMP) is the most widely used network management protocol in TCP/IP network, and is the de facto standard of network management. It not only refers to the Simple Network Management protocol itself, but also represents the network management framework using SNMP protocol, and experiences the development process from SNMPV1 to SNMPv3, this article will discuss its evolution from the following aspects.

SNMPV1 Management model

SNMPV1 management model includes four key elements: Management station, management agent, management information base, management protocol. The following figure shows the relationship of the above four elements.

1. Management Station

Management station is the network administrator and network Management system interface, it is actually a computer running special management software. The management station runs one or more management processes that communicate with the agent on the network through the SNMP protocol, sending commands and receiving an agent's response. The management station implements network resource monitoring by acquiring the value of the MIB object, or by modifying the value of the special variable to enable the agent to perform an action or modify the configuration of the resource. Many management station application process has the graphical user interface, provides the data analysis, the fault discovery function, the network manager can conveniently check the network condition and takes the action when needs.

2, management agent

The hosts, routers, bridges, and switches in the network can be configured with SNMP as a management agent for the management station to manage. Each agent is responsible for maintaining the local MIB to store the status of the managed resources, the operation of the information from the management station, and to respond to requests for action execution, but also to provide some important unsolicited information to the management station asynchronously.

The management station can access the MIB objects of multiple management agents and receive traps from multiple agents, so the management station "manages" many agents from the point of view of operation and control. At the same time, the management agent can also respond to the requests of multiple management stations, is a one-to-many relationship, the management agent in order to control the use of its MIB management station, to protect its own and its MIB, to avoid the desire or unauthorized access, the use of the community concept. The management agent establishes a community for each of the necessary authentication, access control, and agent characteristics. The message from the management station to the agent contains the community name, it plays the role of password, as long as the message sender know the password, the message is considered trustworthy. This shows that this is not a safe way, so many managers simply provide network monitoring functions (GET and trap operations), shielding the network control function (set operation).

3. Management Information Base

MIB is an information repository that contains data about configuration and performance in the management agent, and is the foundation of network management. Each managed resource is represented by an object, and the MIB is a structured collection of such objects. The management information structure defined in RFC1155 gives the overall framework of MIB structure.