A router is a network device that connects two networks (specifically two subnets) together. For example, a router would connect a Local Area Network (LAN) to the Internet. A router is different from a switch. A switch transfers data between network devices on the same subnet, whereas a router transfers data between subnets. In this manner, a router often works in conjunction with a switch.

Network administrators can use routers to connect various LANs together to form a Wide Area Network (WAN).

A router sometimes contains a firewall to block unwanted network traffic; however, technically, a firewall and router are two distinct entities. Consumer “routers” often contain a router, firewall, and switch in one physical device.

Routers are important for OPC communication because automation data must often pass between two networks, such as an Operations Network and a Business Network, between two production units in a plant, or between different facilities altogether. It is therefore important to properly configure a router to enable this type of data exchange.

See also: Switch