SNMP Architecture

The three fundamental members of framework the SNMP are:

1. it arranges managed (managed object)
2. management agent (management agent)
3. he arranges of management (manager)

Every managed system (as an example a simple node, a router, printing or whichever other device that supplies an interface of management SNMP) usually accommodates a management agent (master agent) and a sure number of subagent. The master agent it has at least the role of intermediary between the manager (that it is the remote application that takes the management decisions, as an example under the direct control of the human operator) and the subagent (that they are the executory ones of such decisions). Every subagent is person in charge to relatively put into effect the decisions of management in the context of a particular subsystem or to a particular aspect of the managed system. In systems that supply particularly simple mechanisms of management, master agent and subagent they can meet in an only member able software is to converse with the manager that to put into effect of the decisions; in this case it will be spoken simply about agent.

SNMP uses one clear separation between the protocol of management and the structure of the managed object. In architecture SNMP, for every given subsystem Management Information Base is defined a base said MIB(), managed from the correspondent subagent, which represents the state of the managed subsystem, or better, a projection than such state limited to the aspects of which the management is wanted to be concurred. Draft of a base given that it could be defined, mutuando a term from the reflection, "causal connected": in other words, every modification to the MIB cause a correspondent change in the state of the represented subsystem, and viceversa. To guarantee this property of the MIB is the main function of the subagent that it manages it.

The access to the MIB (in reading and writing) representsthe interface supplied to the manager in order to manage the system. Every MIB, also varying in the specific contents, has the same general structure and the same mechanisms generate them of access from part of manager (the reading and writing of the data). Thanks to the logon motive of the MIB, it is therefore possible to the manager to act on the state of the subsystem in a way that is widely independent from the concrete procedures that must be put in action (from the subagent) in order to extract the information of state represented in the MIB, or to put into effect the state modifications as a result of changes of the contents of the MIB. Therefore, as an example, a MIB data could be had that represents IP address of the managed system; in order to modify such address, to the manager he is sufficient to approach the MIB sovrascrivendo the corresponding data, prescinding of the details of as a such modification comes then concretely "put into effect" on the managed system.

More in detail, the manager it converses with the systems managed essentially in two ways: it sendes demands SNMP and it receives notifications SNMP.