Application layer-simple network management protocol (snmp) is used in network management systems to monitor network-attached devices for conditions that warrant administrative attention. snmp is a component of the internet protocol suite as defined by the internet engineering task force (ietf). it consists of a set of standards for network management, including an application layer protocol, a database schema, and a set of data objects.overview and basic conceptsin typical snmp use, one or more administrative computers have the task of monitoring or managing a group of hosts or devices on a computer network. each managed system executes, at all times, a software component called an agent (see below) which reports information via snmp to the managing systems.essentially, snmp agents expose management data on the managed systems as variables (such as free memory, system name, number of running processes, default route). but the protocol also permits active management tasks, such as modifying and applying a new configuration. the managing system can retrieve the information through the get, getnext and getbulk protocol operations or the agent will send data without being asked using trap or inform protocol operations. snmpv3 inform messages are valuable because they provide a reliable way for this data to be acknowledged by the management system, which is important because snmp is a udp-based protocol. management systems can also send configuration updates or controlling requests through the set protocol operation to actively manage a system. configuration and control operations are used only when changes are needed to the network infrastructure. the monitoring operations are usually performed on a regular basis.the variables accessible via snmp are organized in hierarchies. these hierarchies, and other metadata (such as type and description of the variable), are described by management information bases (mibs).[edit]basic componentsan snmp-managed network consists of three key components:managed deviceagentnetwork management system (nms)a managed device is a network node that contains an snmp agent and that resides on a managed network. managed devices collect and store management information and make this information available to nmss using snmp. managed devices, sometimes called network elements, can be any type of device including, but not limited to, routers, access servers, switches, bridges, hubs, ip telephones, computer hosts, and printers.an agent is a network-management software module that resides in a managed device. an agent has local knowledge of management information and translates that information into a form compatible with snmp.a network management system (nms) executes applications that monitor and control managed devices. nmss provide the bulk of the processing and memory resources required for network management. one or more nmss may exist on any managed network.
