A FRAD (frame relay access device; also sometimes referred to as a frame relay assembler/dissembler) is a box that encapsulates (puts frame relay header and trailer information on) outgoing data packets and decapsulates (removes frame relay headers and trailers from) incoming packets. Frame relay is a system in which data (in the form of packets) from different protocols such as Ethernet, X.25, and the Internet Protocol (IP) is collected into "frames" or larger units of transmission that are delivered in burst-like mode over a switched connection that is, however, a "permanent virtual circuit" (PVC). A PVC ensures that packets always arrive in the right order so that they can be reassembled successfully. Since frame relay does not take responsibility for error detection, the FRAD sometimes includes error detection.
The FRAD is a box, usually close to the user, that provides the interface between the user and a network that uses frame relay. The FRAD is sometimes included as part of a router.