Data-link layer-wans are all about exchanging information across wide geographic areas. they are also, as you can probably gather from reading about the internet, about scalabilitythe ability to grow to accommodate the number of users on the network, as well as to accommodate the demands those users place on network facilities. although the nature of a wana network reliant on communications for covering sometimes vast distancesgenerally dictates slower throughput, longer delays, and a greater number of errors than typically occur on a lan, a wan is also the fastest, most effective means of transferring computer-based information currently available.an x.25 wan consists of packet-switching exchangeatm is a connection-oriented, unreliable (does not acknowledge the receipt of cells sent), virtual circuit packet switching technology. unlike most connectionless networking protocols, atm is a deterministic networking system it provides predictable, guaranteed quality of service. from end to end, every component in an atm network provides a high level of control. atm technology includes: