The author wishes to thank the members of the Munich Network Management (MNM) Team for helpful discussions and valuable comments on previous versions of the paper. The MNM Team directed by Prof. Dr. Heinz-Gerd Hegering is a group of researchers of the University of Munich, the TU München, and the Leibniz Supercomputing Center. Its webserver is located at http://wwwmnmteam.informatik.uni-muenchen.de.