There is now more and more shared vision that future networks will exploit the functionality offered by wavelength division multiplexing (WDM). In particular, WDM offers technical solutions to route, to add and to drop different wavelength channels. In Europe, part or the research on Pan-European Networks is done within the on-going ACTS projects. In particular, WDM networking trials are of optical packet switching. This is in particular the topic of the ACTS project KEOPS. A reference network model including both the optical transport layer and the optical packet layer is presented below.