Simple Network Management Protocol（SNMP）is an Internet Standard protocol for collecting and organizing information about managed devices on IP networks and for modifying that information to change device（ ）.SNMP is a component of the Internet Protocol Suite as defined by the Internet（ ）Task Force.SNMP operates in the（ ）layer of the Internet protocol suite.All SNMP messages are transported via User（ ）Protocol.An SNMP-managed network consists of three key components: a）Managed devices，b）（ ）（i.e.，software which runs on managed devices），and c）Network management station（NMS）（i.e.，software which runs on the manager）.