Simple Network Management Protocol (SNMP) is a UDP-based application-layer protocol used in network management systems to monitor network-attached devices. SNMP is typically integrated into modern network infrastructure devices, such as routers, bridges, switches, servers, printers, copiers, fax machines, and other network-attached devices. An SNMP-managed network consists of three main components: a managed device, an SNMP agent (network-management software running on the managed device), and a Network Management Station (NMS), which monitors and controls managed devices while collecting SNMP data from agents. The NMS (or manager) receives notifications, called traps, on UDP port 162, while the SNMP agent receives requests on UDP port 161.