The Lee algorithm is a well-known technique for finding interconnection routes in applications such as on printed circuit boards. It is a problem highly suited to the use of the parallelism of optics. An optical solution to routing that is based on multirule symbolic substitution is described. As well as single-destination routing on a single layer, the adaptation of the technique for dealing with multiple destinations and multilayer boards is described. Finally, the performance gain of an optical over an electronic implementation of the algorithm is estimated.