“…They differentiate between intra-domain functionalities, responsible for the local domain, and inter-domain functionalities for, e.g., flow configuration between domains. Bagci et al [26] extended an SDN controller with multi-domain controller-to-controller features. They implemented end-to-end service-level management supporting three different service levels (guaranteed quality, best effort plus, best effort), which were used for end-to-end service negotiation.…”