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).