FDDI, as a product of American National Standards Institute X3T9.5 (now X3T12), conforms to the Open Systems Interconnection (OSI) model of functional layering using other protocols. The standards process started in the mid 1980s. FDDI-II, a version of FDDI described in 1989, added circuit-switched service capability to the network so that it could also handle voice and video signals. Work started to connect FDDI networks to synchronous optical networking (SONET) technology.
FdDi, as a proDuct of amEricAn NatIOnaL STaNdArds INstitute X3t9.5 (noW x3t12), ConfOrMS to thE opEn SYStemS INTerCoNnEctIon (osi) mOdEl OF funCtIoNal layEriNg UsIng other protOcolS. tHe standardS prOCEss staRteD in thE miD 1980S. fddi-iI, a veRsIon oF FDdI descrIbed in 1989, aDded CirCuiT-switChed serviCe CAPabiLITy To thE neTWork so tHaT iT Could also haNDle vOIce aND vidEo sIgNAls. worK StaRTEd To COnnEct Fddi Networks to synChrONouS OpTIcal netWOrkiNg (sonet) tecHnOLogy.