Mumbai University > Computer Engineering > Sem 5 > Computer Networks

Marks: 10 Marks

Year: May 2016

Fiber Distributed Data Interface (FDDI) is a standard for data transmission in a local area network. It uses optical fiber as its standard underlying physical medium, although it was also later specified to use copper cable, in which case it may be called CDDI (Copper Distributed Data Interface), standardized as TP-PMD (Twisted-Pair Physical Medium-Dependent), also referred to as TP-DDI (Twisted-Pair Distributed Data Interface).

FDDI provides a 100 Mbit/s optical standard for data transmission in local area network that can extend in range up to 200 kilometers (120 mi). Although FDDI logical topology is a ring-based token network, it did not use the IEEE 802.5 token ring protocol as its basis; instead, its protocol was derived from the IEEE 802.4 token bus timed token protocol. In addition to covering large geographical areas, FDDI local area networks can support thousands of users. FDDI offers both a Dual-Attached Station (DAS), counter-rotating token ring topology and a Single-Attached Station (SAS), token bus passing ring topology.

The FDDI data frame format is:

Where PA is the preamble, SD is a start delimiter, FC is frame control, DA is the destination address, SA is the source address, PDUis the protocol data unit (or packet data unit), FCS is the frame check Sequence (or checksum), and ED/FS are the end delimiter and frame status. The Internet Engineering Task Force defined a standard for transmission of the Internet Protocol (which would be the protocol data unit in this case) over FDDI.

It was first proposed in June 1989 and revised in 1990. Some aspects of the protocol were compatible with the IEEE 802.2 standard for logical link control. For example, the 48-bit MAC addresses that became popular with the Ethernet family. Thus other protocols such as the Address Resolution Protocol (ARP) could be common as well.