Experimental evaluation of hierarchical control over multi-domain wireless/optical networks

5G-Crosshaul aims at reducing network costs by designing an integrated transport (fronthaul/backhaul) network able to fulfill 5G requirements. Such transport networks will consist of heterogeneous technologies that need end-to-end orchestration. In this paper, we evaluate a hierarchical resource management framework for multi-domain wireless/optical networks. More specifically, we deploy a hierarchical 5G-Crosshaul Control Infrastructure (XCI) where child controllers deal with the specificities of each technology whilst the parent controller is in charge of offering to a resource management application (RMA) the appropriate abstraction level and an end-to-end view. To understand the end-to-end behavior related with service setup, we evaluate each network segment (wireless and optical), each plane (application and control planes), and each layer of the hierarchy inside the XCI. In particular, we evaluate the aggregated path setup time (in the order of seconds) as well as each component (wireless domain contributes with tens of ms and multi-layer optical network with hundreds of ms per layer for a total in the order of seconds). Path restoration results reveal the importance of leveraging control of child controllers when requiring fast response to unexpected data plane events, since an important part of the setup delay observed is due to the RMA-parent-child controller interaction and sequential message handling.