Wide Area Network (WAN)

WANs interconnect  LANs. WAN provide LANs access to computer or file servers in other locations. Because WANs connect user networks over a large geographic area, the make possible for business to communicate across greater distance.

Using WANs allow computers , printers, and other devices on LAN to be shared with distant locations. WANs provide large communication across large geographic areas. the ability to send instant message (IM) to someone anywhere in the world provides the same communication capabilities that used to be possible only if the people were in the same physical office. collaboration software provides access to real-time information and resources that allow meetings to be held remotely instead of in person. Wide-area networking has also created a new class of workers called telecommuters - people who never have to leave home to go to work.

WANs are designed to do the following:

• operate over large geographically separated areas
• Allow users to engage in real-time communication with other people  
• Provide full-time remote resources connected to local services
• provide e-mail, world wide web, file transfer, and e-commerce services

Some common WAN topologies:

• Modems (asynchronous dial-up)
• Integrated Services Digital Network (ISDN)
• Digital Subscriber Line (DSL)
• Frame Relay
• T1 or E1 leased line - T1, E1, T3, E3 and so on
• Synchronous Optical Network (SONET) - Synchronous Transport Signal level 1 (STS-1) (Optical Carrier [OC]-1), STS-3 (OC-3), and so on