LONDON, Sept. 19 -- Marconi Plc said that it had won its first major North American contract to supply high-speed optical network products. The company said the multimillion dollar agreement was to supply dense wavelength division multiplexing (DWDM) equipment to IRIS Networks, a consortium of 11 independent telephone companies. "This partnership is a breakthrough for Marconi, as it is our first major DWDM win in North America," Marconi chief executive Mike Parton said in a statement. It gave no exact value for the contract.