Frame Relay
Frame Relay is one of the most popular methods used today to connect WAN links because of its speed, reliability and cost. Frame Relay is a packet-switching technology, which means that your data will travel through your service provider’s network along with other customer’s data.
The service providor programs switches to route your data in the right direction so that it does not get crossed with another customer’s data. Frame Relay operates at the two lower layers of the OSI Model( data link layer and physical layer ) and is a specification on how to encapsulate your data across a WAN Link.
Frame relay does not rely on any certain protocol for error checking. Intead its relies on upper-layer protocols to provide error checking. It relies on TCP to provide error checking in an IP Network.
Frame relay uses Inverse ARP as a way to dynamically map a network layer address to a DLCI. With Inverse ARP, the route can discover the network address of a device associated with a VC.