Used by quite a number of people, Simple Network Management Protocol normally abbreviated as SNMP is a protocol suite component. The protocol is used in the systems that deal with the management of networks. Its main function is to monitor devices, which are attached to the network for conditions that need administrative attention. SNMP comes with standards that are set for the management of networks including data object sets, database schema, and an Application Layer protocol. Management data is usually exposed by SNMP in variables upon the systems that are managed, which are used to describe the configuration of the system. Managing applications can query and set (sometimes) these variables.
A network that is managed by SNMP has three main components. Managed devices are also known as network elements are among the components and they are essentially network nodes that have an agent belonging to SNMP. The managed devices reside on managed networks. Their main function is to collect then store information for management and later make it accessible to NMSs by use of SNMP. Management devices can be switches, bridges, routers, access servers, printers, IP telephones, computer hosts, and hubs. An agent is another component that is basically software for network management which is located in managed devices. It contains local knowledge concerning management information and its function is to translate the information into forms that are SNMP compatible. Network Management Systems are the third component and their function is to execute applications that control and monitor managed devices. They also provide most of the memory and processing resources that network management requires. A managed network can have one or many NMS.
SNMP has three versions. SNMPv1 is the original implementation of the protocol. It works with protocols like UDP (User Data Protocol) CNLS (OSI Connectionless Network Service) Novell Internet Packet Exchange (IPX), Internet Protocol (IP), and DDP (AppleTalk Datagram -Delivery Protocol). SNMPv1 is very popular. SNVPv2 is a revision of version 1 and has improvements on security, confidentiality, manager-to-manager communications, and performance. It also has GETBULK used to retrieve management data in large amounts upon request. SNMPv3 is the recent standard version and among the services it provides are privacy, access control, and authentication. SNMPv1 and SNMPv2 are incompatible in the areas of protocol operations and message formats. Messages belonging to SNMPv2 use differing Protocol Data Unit (PDU) and header formats from messages belonging to SNMPv1. Two protocol operations in version 2 are not in version 1.