Wide Area Network

WAN comprises of routers, routing protocol and transmission facilities properly constructed to enable LAN to be network together, regardless of how much geographical distance separating them.  Wide Area Networks technology base include the following

·         Transmission facilities

·         Communication hardware including CSUS/DSUS (Channel Service Unit/Data Service Unit, routers and Switches

·         Internetwork addressing

·         Routing protocols

Wide Area Network Transmission facilities

Ranges from 9.6KBS(Kilobyte per seconds) to 44.7MBS and beyond in size (bandwidth), they are support a digital stream of data at a fixed and predetermined transmission rate and there are two types of primary transmission facilities in wide area network

·         Circuit Switching Facility

·         Packet Switching Facility

Circuit Switching Facility

Circuit switching is a communication method that creates a switch, dedicated path between two end stations e.g. a telephone line. At telephone is hardwiring to a central office telecommunication switch that is owned and operated by local exchange carrier. Any telephone can establish a connection to any other telephone through a series of intermediary central office switches. The connection is a physical circuit dedicated to that session for the duration of communication session. After the telephone terminates their sessions the physical circuit through the switch telecommunication infrastructure is down. The resources are then freed up to the next coil. The creation of dedicated physical circuit is the essence of circuit. Circuit switch transmission facilities include leased lines, ISDN (Integrated Service Digital Network)

Packet Switch Facilities

This  features an internal packet format that is used to encapsulated. To encapsulate data to be transported. They do not provide a dedicated connection between two location instead the premises facility, interconnect with the telecommunication carriers switched infrastructure. Packets are forwarded in a connectionless manner through this commercial packet switched network (PSN) example are X.25 and frame relay  

·         X.25 – Very old WAN communication protocol that support both switch and permanent virtual circuit, they are less expensive, transmit at 56kbps

·         Frame relay - features small size packets and has got few error checking mechanism. It support transfer of packet through only permanent virtual packet between the network end point routers