For a high-speed metropolitan area network (MAN), a ring network based on the wavelength-division multiplexing (WDM) technology has been deployed to solve global information explosions in the Internet. To enhance the network performance, we have studied the node configuration problem, particularly for the one with the double-ring architecture where each node is equipped with fast-tunable transmitters and wavelength-fixed receivers (TT-FR) as fiber interfaces. In our studies, by adopting additional transmitters/receivers, nodes can afford far larger traffics than conventional ones. This fact indicates that plural nodes should be aggregated into one so that the transmitters/receivers can be utilized more efficiently. This paper presents a definition of the node aggregation problem for the WDM ring network and its simple greedy heuristic algorithm. The simulation results using the network simulator show the effectiveness of our approach.