There are many types of devices that are specific to WAN environments, including:
- Dialup modem - Considered to be a legacy WAN technology, a voiceband modem converts (i.e., modulates) the digital signals produced by a computer into voice frequencies that can be transmitted over the analog lines of the public telephone network. On the other side of the connection, another modem converts the sounds back into a digital signal (i.e., demodulates) for input to a computer or network connection.
- Access server - Concentrates dialup modem, dial-in and dial-out user communications. Considered to be a legacy technology, an access server may have a mixture of analog and digital interfaces and support hundreds of simultaneous users.
- Broadband modem - A type of digital modem used with high-speed DSL or cable Internet service. Both operate in a similar manner to the voiceband modem, but use higher broadband frequencies and transmission speeds.
- CSU/DSU - Digital-leased lines require a CSU and a DSU. A CSU/DSU can be a separate device like a modem or it can be an interface on a router. The CSU provides termination for the digital signal and ensures connection integrity through error correction and line monitoring. The DSU converts the line frames into frames that the LAN can interpret and vice versa.
- WAN switch - A multiport internetworking device used in service provider networks. These devices typically switch traffic, such as Frame Relay or ATM and operate at Layer 2.
- Router - Provides internetworking and WAN access interface ports that are used to connect to the service provider network. These interfaces may be serial connections, Ethernet, or other WAN interfaces. With some types of WAN interfaces, an external device, such as a DSU/CSU or modem (analog, cable, or DSL), is required to connect the router to the local service provider.
- Core router/Multilayer switch - A router or multilayer switch that resides within the middle or backbone of the WAN, rather than at its periphery. To fulfill this role, a router or multilayer switch must be able to support multiple telecommunications interfaces of the highest speed used in the WAN core. It must also be able to forward IP packets at full speed on all of those interfaces. The router or multilayer switch must also support the routing protocols being used in the core.
Note: The preceding list is not exhaustive and other devices may be required, depending on the WAN access technology chosen.
WAN technologies are either circuit-switched or packet-switched. The type of devices used depends on the WAN technology implemented.