inline network device
An inline network device is one that receives packets and forwards them to their intended destination.
Common inline network devices include routers, switches, firewalls, and intrusion detection and intrusion prevention systems, web application firewalls, antimalware and network taps. Typically residing on layer 2 or layer 3 of the network topology, inline network devices are considered critical to the function of an enterprise network. Any failure of an inline network device typically results in dropped packets, which can cause errors in the computing programs and processes that rely on the successful transmission of those packets.