Wide area network

A Wide Area Network (WAN) is a telecommunication network that covers a broad area (i.e., any network that links across metropolitan, regional, or national boundaries). Business and government entities utilize WANs to relay data among employees, clients, buyers, and suppliers from various geographical locations. In essence this mode of telecommunication allows a business to effectively carry out its daily function regardless of location.

 

Types of WAN Technologies

In this article:

• Introduction
• Dedicated wan connection or leased line
• Circuit switched networks
• Packet switched networks
• WAN Services

					Wide Area Networks (WANs) are used to interconnect networks that are not physically close to each other, might be physically separated across the cities, across regions, or even across geography. Currently there are many WAN technologies available. Primary different between WAN technology and LAN technology is about the distance that separates the interconnected networks. WANs use different transmission media, hardware, and protocols.
					Theigure 1 shows WAN connection diagram describes each of WAN elements and functions in the WAN technologies concept. DTE (Data terminal equipment) is a device on the side of WAN link (resides on the subscribers premises) that sends and receives data. DTE (which is usually a network router, or a computer, or a multiplexer) is a mark point between the LAN and the WAN. DTE is a device that communicates with the DCE at the other end. Demarcation points (Demarc) is the points as the network interface or point of presence where the telephone wiring company connects to the clients. Local loops is the cable that extends from the demarc to the CO (central office) which is maintained by the Telco. It can be UTP, fiber optic, or combination of both and other media. DCE (data circuit terminating equipment) is a device (which is typically a router at the ISP) that communicates with both DTE and WAN clouds. DCE is a device that supplies clocking signals to DTEs. A modem or CSU/DSU at the customer site can be classified as DCE. DTE and DCE can be similar device / router but with different role and function. WAN Cloud, the hierarchy of trunks, switches, and CO – central office, that makes up a network telephone lines. Physical structure varies, and different networks with common connection points may overlap, so that’s way it is represented as a Cloud. The important part is that data goes in, travels through the line, and arrives at the destination. PSE (packet switching exchange) is a switch on a carrier’s packet switched network. PSEs are the intermediary points in the WAN cloud.
					Circuit switched networks circuit switched diagram This circuit switched WAN connection type gives you an alternative to leased lines, letting you use shared lines. See figure 3 – circuit switched -diagram.  This WAN connection type works both ways, allowing both dial-in and dial-up WAN connections. When you use this circuit switched WAN connection: The sending computer dials-in to the line and the WAN connection is set up. The receiving computer sends acknowledgement and locks the line. The sending computer transmit the data over this WAN connection After the transmission is complete, the connection is released for other users. A circuit switched network uses switched virtual circuit (SVCs). A dedicated data transmission path is established before communication begins by throwing electrical switches. The path remains until the communication ended.   Packet switched networks Packet switched Diagram Packet switched networks do not require a dedicated or temporary reserved line. See figure 4 packet-switched diagram.  Instead, a message’s path is dynamically set as the data flows through the network. This WAN connection type has the following characteristics: Messages are divided into packets. Packets travel independently through the internetwork (i.e. take different paths) Packets are reassembled into the correct order at the receiving end Sending and receiving devices assume an ‘always on’ connection (no dials-up needed) This wan connection type – packet switched networks use permanent virtual circuits (PVCs). Although a PVC looks like a direct, dedicated WAN connection, the path each packet can take through the internetwork can vary. Dedicated and switched networks have an always available connection to the network but circuit switched networks need to establish connection first via a dial-up mechanism between devices. In a dial-on-demand routing the routers open connections automatically when the data needs to be sent, and will close automatically when the line is idle.