Wavelength agility in multihop lightwave networks

The multihop architecture, which provides a way of tapping the capacity potential available in lightwave networks, is described. Within this architecture, each network node is equipped with some small number of transmitters and receivers, each of which can communicate on one wavelength. Transmitters and receivers are connected to an optical medium, which is physically configured in such a way that the entire spectrum of wavelengths in use is potentially accessible by each node. Then, an assignment of transmit and receive wavelengths to each node defines the logical connectivity among nodes. Furthermore, the use of optically agile transceivers (i.e. slowly tunable lasers or optical filters) permits the logical connectivity to be updated in response to changing traffic patterns and failure/recovery of nodal transmitters and receivers. The flow and wavelength assignment problem is studied. Solutions in which the traffic flows over a derived connectivity diagram such that the largest flow on any link is minimized are sought. Examples of the resulting connectivity diagram and traffic flow are presented for selected nonuniform point-to-point traffic matrices