WAN - Wide Area Network

A wide area network (WAN) is a geographically distributed private telecommunications network that interconnects multiple local area networks (LANs). A LAN is a group of computers and network devices which are all connected to each other, typically from within a short relative geographical distance. In an enterprise or business, a WAN may consist of connections to a company's headquarters, branch offices, colocation facilities, cloud services and other facilities. Typically, a router or other multifunction device is used to connect a LAN to a WAN. Enterprise WANs allow users to share access to applications, services and other centrally located resources. This eliminates the need to install the same application server, firewall or other resources in multiple locations, for example.

WANs are not restricted to the same geographical location as a LAN would be. A LAN can be set up in any number of geographical areas and be connected to a WAN—meaning a WAN is not constrained to one specific location.

A virtual private network (VPN) facilitates connectivity and security between WAN sites. Different VPNs can be utilized for different use cases. An IPsec VPN is more commonly used in continuously open site-to-site connections, such as those between branch offices and headquarters locations. An SSL VPN is often the preferred choice for enabling remote access for individual users because the data transmitted from users across the WAN is encrypted. Direct fiber optic links are also used to connect sites on a WAN – and they almost always offer greater performance, reliability and security than VPNs, but they are cost-prohibitive for most enterprises to procure and operate.

Types of WAN connections and how WAN connections work

WAN connections can include wired and wireless technologies. Wired WAN services can consist of multiprotocol label switching, T1s, Carrier Ethernet and commercial broadband internet links. Wireless WAN technologies can include cellular data networks like 4G LTE, as well as public Wi-Fi or satellite networks.