We study the configuration issue of three-stage multi-granularity optical cross-connects (MG-OXC) for the dynamic traffic model in all-optical networks. From the single node point of view, we propose a configuration algorithm to configure different granularity cross-connects for arrival sub-requests with different traffic types and bandwidths. The performance of the configuration algorithm is evaluated by simulation and, furthermore, is validated by experiment based on our flexible Multi-functional Optical Switching Testbed (MOST).

The need for greater transmission capacity through optical fiber has been met so far by the wide scale deployment of wavelength division multiplexing (WDM). Still, to manage and access this bandwidth, the next growth challenge will most likely emerge at the switching nodes, where processing is needed to groom the ever diverse and changing traffic. The eventual goal is to reduce the amount of complex electronics, and thus, the cost, by migrating to the all-optical network, where data is switched and routed transparently in optical form, with a minimum amount of electronic processing. As a first step in this direction, optical cross-connects (OXCs) and optical add-drop multiplexers (OADMs) are already being introduced commercially to perform basic routing and switching functions for protection and allocation. Eventually, we envision an optical packet switched network layer that features: (i) bit rate transparency, (ii) protocol transparency, and (iii) fast switching with fine granularity. With these characteristics, an optical packet switched network layer can be a high performance and cost competitive solution for future networks. Several networking functions will be needed to deploy the all-optical transparent layer. Wavelength conversion will allow the reuse of wavelengths in the network and may help alleviate contentions. Optical synchronization and optical packet header processing (for routing and switching) will increase throughput and reduce latency. Last, but not least, all the above solutions will need to be bit rate and modulation format independent (or at least be able to handle a wide range of bit rates and modulation formats).

In order that they fully support human activities, new network services and applications are overwhelming conventional ones, such as telephony, facsimile, and telegraph. Demands for digital networks are exploding, not only in terms of quantity but also quality. Nobody can predict where these demands will lead. Traffic engineering, which is impossible in pure Internet protocol (IP) -based networks, is recognized as being indispensable for quality of service (QoS) control. It includes guaranteed services in terms of bandwidth, delay, delay variation (jitter), and service protection. The "engineered tunnel" through IP network supports virtual private networks (VPNs) and allows us to develop voice-over-IP (VoIP), teleconferencing and other secure private network services. This paper proposes the "photonic router" which makes use of wavelength-based networks for signal routing. IP packets having the same destination are bundled into a wavelength path. Interchange nodes along the path route control path routing on the basis of wavelength information, not on IP headers, which can not be read or processed with current optical techniques. In short, wavelength path routing offers "cut-through" in the photonic layer. This paper shows its feasibility by describing the combination of an optical cross-connect, payload assembler/disassembler, label controller, and IP router. Optical cross-connect systems, which are now being intensively studied worldwide, are deemed to be key equipment for a wavelength-path network with centralized control system. This paper proposes to apply the cross-connect to an IP network with distributed autonomous control.

This paper presents a cost-effective network for very large ATM cross-connects. In order to develop it, we propose the delta network with expanded middle stages. This proposed network is the intermediate network between a nonblocking network and the delta network with respect to the cost of hardware and internal blocking probability. Using this network, we explore the tradeoff between the cost and internal blocking probability, and derive the optimum configuration under temporarily deviating traffic. Internal blocking occurs when input traffic temporarily deviates from its average value. However, we cannot evaluate the internal blocking probability by using conventional traffic models. In this paper, we adopt temporarily deviating traffic such that all traffic is described as the superposition of the paths which are defined by traffic parameters. As can easily be seen, the path corresponds to virtual path (VP) or virtual channel (VC). Therefore, we believe that our model describes actual traffic more exactly than conventional models do. We show that the optimum configuration is the proposed network whose expansion ratio γ=3 when the maximum number of paths that can be accommodated in one link is greater than 22. This network achieves the internal blocking probability of 10-10. As an example of this network, we show that the proposed network of size 7272 is constructed with only 40% of the hardware required by the nonblocking network.