Fiber Distributed Data Interface (FDDI)
FDDI is the standard data transmission LAN technology with the data transfer rate of 100Mbps over multi-mode fiber optic cables. The protocol used for FDDI is derived from standard IEEE 802.4. FDDI uses a dual ring model based on the Ring topology, consisting of primary and secondary rings.
If data is transferred to the primary ring, then the data flows in one direction, whereas, in case of the secondary ring, flow of data is in the opposite direction. The purpose of using two token rings is to restore backup. In the FDDI technology, each computer in the network is known as FDDI Workstation.
- Start Delimiter: Specifies the start of a frame through signaling pattern which makes it unique from the rest of the frame.
- Frame Control: Specifies the size of the address field. It also verifies the data and other control information in the frame is synchronous or asynchronous.
- Destination Address: Specifies the six bytes long destination address. It consists of a unicast, multicast, or broadcast addresses.
- Source Address: Contains six bytes long source address and identifies the single station that sends the frame.
- Data: Contains the defined information for the upper layer protocol and control information.
- Frame Check Sequence: Uses four bytes to store the calculation value of Cyclic Redundancy Check (CRC is an error detecting code that identifies accidental changes in the data) that is used for error detection.
- End Delimiter: Contains the unique symbol that indicates the end of the frame.
- Frame Status: Enables the source station to verify the error has been occurred or not. It also allows the source station to verify that the frame has been discerned and copied by the receiving station or not.