In this paper, a new scheme has been proposed to achieve high-performance local area network adoptii/g 5～15nm separdted eosrse wavelength division multiplexing (CWDM) technique. Using this scheme, the current single-wavelength gigabit Ethernet can be sesmlessly upgrdded to multi-wavelength network. Not only can the network bandwidth be broadeneds but also wavelength routing can be achieved among different sub-networks. The dam packet communication latency can be reduced one-to-two magnitudes in comparison with that of the current gigabit Ethernet. To expand the network scale, multi-wavelength-window CWDM teehifique can be adopted. Two kinds of network interface cards have been designed using opto-electronics devieosst the 850nm and 1300nm wavelength windows, respectively. Experiment.s indicate that the two kinds of CWDM signals can be selectively received at the corresponding optical detectors. By introducing two optical droppiing devices in the network, multi-wavelength-window (850nm, 1300nm and 1550nm) CWDM system can be achieved.