In IP over WDM networks, optical paths (OP's) form a virtual topology seen from the upper IP layer, and greatly relieve the burden of electronic processing thanks to optical bypasses. However, in contrast to the circuit-switching, connection-oriented and coarser OP's, the IP is packet-switching, connectionless and finely granular in nature. Special care should be taken in the control plane to bridge the gap. In our research, we incorporate the idea of optical flow. Optical flows are optically switched in intermediate nodes and converted into electronic form at termination to treat small nested flows. Two modes of optical flow switching (OFS) are examined. One is optical burst switching (OBS), which sends control packet ahead of data to announce a switching and make future reservations. The other is Optical Grooming Switching (OGS), which put packet flows into finer container with discrete yet flexible bit rate. We find that both of these two modes use statistical multiplexing to bridge the gap between IP packets and WDM OP's, and such function is fulfilled respectively by scheduling in OBS and by framing in OGS. Taking snapshots of statistical multiplexing, we formulate the bandwidth distribution (BWD) of the whole OFS networks and the bandwidth usage (BWU) over each node pair. The BWD can be expressed by the product of a traffic-independent grooming matrix with the traffic demand matrix under a given virtual topology. Changes to the grooming matrix are reflected by adjustments in framing or scheduling. Three distinct states of BWU are also identified to determine the initiation of such changes. The BWU states are hence proposed to add to the extension of existing routing protocols.
In addressing the integration of IP and WDM networks, we propose a joint operation approach. Through reconfiguration or real-time setup of lightpaths, joint operation focuses on optimizing network performance or guaranteeing it to a defined level under current network configuration and dynamic data traffic pattern at the network operational stage. Our model features a separation of control plane and data plane. The data plane Formulations have been studied in building the model, and the initial findings help in understanding the behavior of data plane and designing the routing and signaling protocols within control plane.
In integration of IP and WDM networks, there are two main approaches. One is joint planning approach; the other is joint operation approach. Joint planning typically addresses an optimality problem on total network cost given a certain data traffic pattern and some physical constraints at the network planning stage; while through reconfiguration or real-time setup of lightpaths, joint operation focuses on optimizing network performance or guaranteeing it to a defined level under current network configuration and dynamic data traffic pattern at the network operational stage. On contrary to the (semi-) static virtual topology in joint planning, the joint operation approach maintains a dynamic virtual topology. We propose an integration network model with separated control plane and data plane. Formulations have been studied in building the model, and the initial findings may help in designing the routing and signaling protocols.
This paper presents the test results in the initial phase that we are constructing a self-healing all-optical network testbed, which is called SHAONET. The completed testbed will be used to demonstrate broadband applications based on wavelength routing + WDM + SDH + ATM and Ethernet transport of multimedia signals from multimedia terminal and video server. The design, implementation and performance of the testbed are discussed.