FDDI is similar to token ring in technology. The architectural structure uses the notion of a token and a station required to capture the token before it can transmit data onto the ring. Frame relay Frame relay is a lower-layer protocol technology. It is similar to X.25 except that routing decisions are made at the data-link layer within the network. Multiple speeds are supported.
Frame relay can also support video and voice transfer in addition to data transfer.
By definition, ISDN is a protocol. It has a set of standards that define its operation. It is technology implemented in many regional telephone companies. Users of ISDN realize benefits of it such as receiving higher speeds through existing telephone infrastructure. ISDN technology supports data, video, and voice.