How to treat an “interface” of a router or a switch?
Nagios defines two types of objects to monitor—host and service. A host is a computer,
network device, printer, UPS or device that can be accessed via the Internet Protocol (IP). A service
can be a real network service such as POP3, SNMP and HTTP, or other information such as processor
load, disk usage, or temperature that can be accessed locally within a host. Nagios makes no distinction
among different types of devices like servers, routers, or switches. Nagios treats every device
generically as a host. This makes it problematic for networks that consist of many routers and switches
because these network devices require more complex monitoring for their interfaces.