Explain about the SNMP manager.

The SNMP manager, also referred to as a Network Management Station (NMS), provides a user interface through which network administrators can monitor and manage their network. The manager fulfills the role of a client in the client/server model and is available in a variety of formats including command-line interfaces, graphical user interface (GUI) applications, and fully automated applications. The SNMP manager is responsible for issuing requests to the SNMP agent. These requests can be queries to obtain the value of a MIB object, or they can be requests to set the value of a MIB object. SNMP managers also can listen for notifications or alerts, called traps, generated by components in the SNMP community .

An SNMP manager can make the following types of requests to the SNMP agent: getRequest Requests that the agent return the value of the specified object. getNextRequest Requests that the agent return the first valid value following the specified object. For example, assume a getNext is executed for ifType (1.3.6.1.2.1.2.2.1.3). Assuming the first valid instance of ifType is ifType.1 (1.3.6.1.2.1.2.2.1.3.1), this is the value that the SNMP agent will return. getBulkRequest Performs the same function as the get request, but allows the manager to query more than one object per request. This is only valid using the SNMPv2c security model . setRequest Requests that the SNMP agent set the value of the specified object. walk Implements a series of getNext requests such that an entire sequence of objects is returned to the manager. In each iteration of the getNext series, the last object returned becomes the next object on which a getNext is executed. The walk ends when an object is returned that is beyond the scope of the request. An example of this is provided in Fig. 6. Note that the walk request is not architected in the SNMP communication that occurs between the SNMP manager and SNMP agent. Instead, it is a convention widely used by most SNMP managers.