Routed Wavelength WDM Networks

An optical fiber can potentially have more than 30 THz of bandwidth that can be exploited by future generation broadband ISDN networks. However, because of the mismatch between optical transmission and electronic processing, the network transmission rate cannot exceed few Gbps. One popular solution to this problem is to employ wavelength division multiplexing (WDM) by fragmenting the whole bandwidth of the optical fiber into a number of narrow band (say, 1 Gbps) channels. The source party can communicate with its destination party through these channels under the control of a given protocol. In WDM networks, there are essentially two types of architectures, passive switch networks and active switch networks. A passive switch network uses a passive star coupler to split the inlet lightwave to all other outlets. Because the passive star coupler can be considered as a broadcasting device, this single-hop system is known as a broadcast and select WDM network [7]. In this type of system, network-wide status and control information can be easily obtained. As a result, through proper scheduling, the channel efficiency can be considerably high. In addition, due to the accuracy of the control information, a given qualityof-service (QoS) can be controlled and guaranteed relatively easy. However, to make a complete connection, the transceivers on each node have to frequently