What is a WAN port?

Most networks consist of two main zones – the local area network (LAN) and the wide area network (WAN). A LAN is the internal network, whether it’s a house with two computers or an office building with thousands. The WAN is the network outside the LAN; these are other internal networks and the complete Internet. A WAN port is the gateway through which information passes back and forth between the LAN and WAN.

A router with a cable connected to the WAN port.

Most users will find a WAN port on a network router. A typical home router has one WAN port and four LAN ports. Some routers refer to these as uplink (to the WAN port) and wired connections (to the LAN ports). This port receives information from a high-speed Internet source, such as a cable modem, and splits it across multiple machines within the home network. While most home routers have four LAN ports, there can be as few as zero or an unlimited number, though rarely more than eight.

Back of a router, showing the power, WAN and LAN ports.

All five of these ports appear as rectangular holes on the back of the device. Each of them is designed to have a network cable connected to it. The WAN port is usually separated from the other ports for easy identification, but is otherwise similar to LAN ports.

The important difference in the two types of ports is inside the router. The WAN port receives information from the external network or the Internet. The information is filtered through the router’s internal firewall and routing system. Then the information is sent to the appropriate LAN port or over a wireless connection to a wireless source.

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In addition to routing and firewall capabilities, routers also include switching functions. This allows computers connected via LAN ports to only communicate with each other. This switching function bypasses the router’s default firewall and the computers are all on the same network. Users can use this function to connect multiple routers together to increase the size of their network.

If they connected multiple routers using the WAN port, they could have multiple internal networks that operate independently of each other. For example, high-speed information arrives at a single router, and that router has connections from its LAN ports to three other routers, where it connects to the WAN ports. These internal networks would contain independent information and would be no more connected to each other than to a network in a different building.

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