In inter-connected optical networks, users submit lightpath requests at the time they wish to establish the lightpath. The service provider consults the information gathered by the inter-domain routing protocols for available resources. For each request, the network must decide immediately whether to accept or reject the request. In this model, there is always the uncertainty of whether the user will be able to establish the desired lightpath at the desired time or not. Furthermore, in the context of a number of applications, e.g., Grid applications, users need to setup lightpaths in advance to perform their activities that are planned in advance.

In this paper, we propose a scheme that allows the setup of inter-domain lightpaths in advance; it extends the Optical Routing Border Gateway Protocol (ORBGP) to get information about inter-domain paths and availability of wavelengths over a certain period of time in the future. One of the key innovations of the scheme is that it provides the user with alternatives, carefully selected, when his/her request cannot be accommodated because of resources shortage.