Many companies use Local Area Networks (LANs) to interconnect their desktop PC and mainframes. However, interconnecting LANs to other sites often require the use of a wide area service or Wide Area Network (WAN). This connection from LAN to WAN is where the challenges emerge.  To understand this challenge, let's look at each network. LANs have very high levels of performance (bandwidth) and responsiveness at reasonable cost. WAN circuits are normally thinner, longer, have greater delay, carry less traffic and are more expensive. In addition, bandwidth-intensive applications and large-file transmission that have bursts of unpredictable data sizes and patterns cannot tolerate large delays across WAN links. Thus, the challenge is to optimize WAN services that can economically provide high bandwidth on demand to small businesses or corporations at a reasonable cost. Frame Relay is a network interface designed to meet this need.