Comprehensive design for control and data planes in wavelength-routed optical networks

We propose a control plane design methodology for optical backbone networks, which attempts to minimize the network congestion without compromising the network restoration response against link failures. Notwithstanding the low bandwidth requirements for control functionalities used in the slower backbone networks, the evolving control plane operations in optical backbones are going to demand significantly larger capacity. However, this demand is expected to remain well within the maximum capacity of a lightpath in the emerging wavelength-routed optical networks (WRONs). In view of this, we propose to setup lightpaths on some judiciously selected fiber links (with point-to-point lightpaths between neighbouring nodes), on a specific wavelength throughout the network and utilize an appropriate fraction of the same set of lightpaths for carrying control information, forming thereby the control plane of a WRON. The remaining bandwidth of these lightpaths is however utilized to carry the data traffic along with all other lightpaths of the WRON, forming the data plane at large. We carry out simulation studies on NSFNET (42 links) and Deutsche Telecom (DT) network (46 links), employing possible control planes using both symmetric (all 42 and 46 fiber links included in control plane, respectively) as well as asymmetric (using fewer fiber links than symmetric case) configurations, e.g., for NSFNET with 38, 32 and 28 links, and for DT network with 40, 34 and 28 links. The results of our simulations indicate that, the proposed hybrid design of control plane with a mix of asymmetric topology and in-band transmission can bring down network congestion significantly with respect to symmetric out-of-band (dedicated fully-reserved lightpaths for control plane), without sacrificing in respect of the network restoration time while recovering from single-link failures.