In general, the port at which a router connects to a given network. For a given network, the port on the router that is directly connected to the network is called a local router interface, while any port on the router that is connected to a different network is called a remote router interface. Each interface of a router has a unique MAC address, just like a network interface card (NIC) in a computer.
In the Routing and Remote Access Service (RRAS) of Microsoft Windows 2000, a router interface is a physical or logical interface over which packets are forwarded. These packets can be unicast packets of Internet Protocol (IP), Internetwork Packet Exchange (IPX), or AppleTalk, or multicast packets of IP. Routing interfaces in Windows 2000 RRAS can be
If only one router is connected to a network, the local router interface is the default gateway for all hosts on that network. Windows 2000 and Windows NT support configuring additional gateways by using the Advanced button on the TCP/IP property sheet.