|  | 7.2 | Monitoring the Network
| 7.2.4 | Simple network management protocol
SNMP is a protocol that allows management to transmit statistical data over the network to a central management console. SNMP is a component of the Network Management Architecture. The Network management Architecture consists of four major components. 1. Management Station: The management station is the network manager's interface into the network system. It has the programs to manipulate data from and control the network. The management station also maintains a database of management information (MIB) extracted from the devices under its management. 2. Management Agent: The management agent is the component that is contained in the devices that are to be managed. Bridges, routers, hubs, and switches may contain SNMP agents to allow them to be controlled by the management station. The management agent responds to the management station in two ways. First, through polling, the management station requests data from the agent and the agent responds with the requested data. Trapping is a data gathering method designed to reduce traffic on the network and processing on the devices being monitored. Instead of the management station polling the agents at specific intervals continuously, thresholds (top or bottom limits) are set on the managed device. If this threshold on the device is exceeded, the managed device will send an alert message to the management station. This eliminates the need to continuously poll all of the managed devices on the network. Trapping is very beneficial on networks with a large number of devices that need to be managed. It reduces the amount of SNMP traffic on the network to provide more bandwidth for data transfer. 3. Management Information Base: The management information base has a database structure and is resident on each device that is managed. The database contains a series of objects, which are resource data gathered on the managed device. Some of the categories in the MIB include Port interface data, TCP data, and ICMP data. 4. Network Management Protocol: The network management protocol used is SNMP. SNMP is an application layer protocol designed to communicate data between the management console and the management agent. It has three key capabilities. The ability to GET, the management console retrieving data from the agent, PUT, the management console setting object values on the agent, and TRAP, the agent notifying the management console of significant events. The key word to remember in Simple Network Management Protocol is Simple. When SNMP was developed, it was designed to be a short-term system that would later be replaced. But just like TCP/IP, it has become one of the major standards in Internet-Intranet management configurations. Over the last few years, enhancements have been added to SNMP to expand its monitoring and management capabilities. One of the greatest enhancements to SNMP is called Remote Monitoring (RMON). RMON extensions to SNMP give the ability to look at the network as a whole as opposed to looking at individual devices.
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