Applying the Semantic Web to Optical Networks Jeroen van der Ham 1⋆ , Paola Grosso 1 , Ronald van der Pol 2 , Andree Toonk 2 , and Cees de Laat 1 1 System and Network Engineering research-group, Universiteit van Amsterdam 2 SARA Computing and Networking Services Amsterdam, the Netherlands Abstract. Current research networks allow end users to build their own application-specific network paths (lightpaths). This requires a clear communication between the requesting application and the provider. The Network Description Language (NDL) is an RDF-based vocabulary, de- signed to describe optical networks. These descriptions aid the appli- cation in understanding the possibilities and allow it to clearly express a request to the provider. This article introduces NDL and shows its current applications in optical research networks. 1 Introduction The Network Description Language (NDL) is an ontology based on RDF. NDL is primarily intended for use within optical hybrid networks, and more specifically for lightpath planning and provisioning. On these hybrid networks, researchers can request lightpaths through the network. These lightpaths can be used to quickly move large amounts of data, or to get a guaranteed fixed quality of service regarding bandwidth, delay, or jitter. Applications that require these kinds of services include the experiments in the new particle accelerator at CERN, the LHC[1], which will produce several Petabytes per year. This data is spread to several research institutes around the world. Another example is the eVLBI community[2], where experiments are conducted using several radio-telescopes in parallel. The data from these telescopes is sent to a correlator station, where the data is combined in real- time. This effectively creates a large interferometer that can be used to study radio objects in the sky. Consistent delay, jitter and no loss of data is very important in this case. NDL provides a common semantic to the application and to the service provider, so that the communication between the two is unambiguous. One of the advantages of using NDL over other network description models, is that we can leverage already established semantic web tools while using an ontology specifi- cally designed for the optical realm. This makes the application and deployment of NDL straightforward. The rest of the article is organised as follows: section 2 describes hybrid net- works and the concept of lightpaths. In section 3 we describe related work, both ⋆ Corresponding author: vdham@science.uva.nl