Dealing with the explosive increase in the amount of Internet traffic requires high-speed and huge capacity Internet protocol (IP) backbone networks. Existing IP backbone networks are constructed using point-to-point wavelength-division-multiplexing (WDM) transmission systems, where all the wavelengths are terminated link-by-link, so that rather expensive optical/electrical conversions are necessary at every node. In these systems, since every IP packet is routed at each intermediate node based on the header information, a header processing bottleneck will occur when the node input traffic exceeds several hundreds of gigabits per second. In order to mitigate these problems, an optical cross-connect (OXC) function that employs wavelength routing of the optical paths (OPs) will provide an effective solution. This paper proposes a network design method where electrical and photonic multiprotocol label switching (MPLS) technologies are used; the network is referred to as a photonic IP network. We first propose new algorithms that minimize the network cost in a multilayered network comprising electrical label switched paths (LSPs) and optical LSPs (optical paths that are controlled using the MPLS mechanism). The particular point of the proposed algorithms is that they include different cost minimization scenarios appropriate for the different OLSP provisioning conditions that are chosen as the first step in the design stage. The effectiveness of the proposed algorithms and the benefits of the OLSPs are quantitatively evaluated through various simulations.

Multiple fiber ring (MFR) networks employing the optical path (OP) concept are discussed to realize robust networks. The architecture is superior to that discussed in several testbeds, with respect to fault recoverability. Both the OP based and non-OP based MFRs can develop several architectures, each of which provides different performance regarding network resource utilization. The required node system scale can be a good measure in determining the network performance. Network design simulations, varying path distribution patterns, have been performed and they elucidated the criteria for selecting the most suitable architecture in terms of resource utilization.

To realize a large scale and robust photonic transport network, this paper proposes a network protection strategy and maintenance signaling flow for WDM optical path transport networks. The network protection strategy is applicable for mesh-type WDM optical path transport networks, and the OA&M flow that is required for the network to recover from failures are clarified. The proposed OA&M flow does not rely on the OP-AIS (optical path alarm indication signal) generation method. This signaling method can also be applied to the all-optical type network.

This paper proposes optical path accommodation design algorithms for both the wavelength path (WP) and virtual wavelength path (VWP) schemes with or without failure restoration. The optical path (OP) employs WDM/FDM (wavelength/frequency division multiplexing) and wavelength routing in the path layer of the transport network. The proposed algorithms adopt some heuristic approaches to the algorithmic complexity caused by the NP-completeness of the wavelength assignment problem. The objective function is taken as minimizing the average total number optical path cross-connect (OPXC) ports, in other words, OPXC system scale. Utilizing the developed algorithms, extensive simulations quantitatively evaluate the OPXC system scale requirements of a large scale network whose physical topology and path demand distribution pattern are arbitrary. The simulations reveal the basic difference between the WP and VWP schemes.

The optical path (OP) technology, which employs both wavelength-division multiplexing and wavelength routing, will be the key to enhanced network integrity and an ubiquitous broadband integrated services digital network (B-ISDN) in the future. To construct the OP network, path accommodation design that can solve simultaneously the problems of path routing and wavelength assignment must be established. Since optical wavelengths are scarce resources, even with state-of-the-art technologies, the available number of wavelengths that can be multiplexed into a fiber is restricted to a relatively small number. This entails space division multiplexing with multiple fibers in the link in order to accommodate the large number of paths within a link. This paper proposes novel OP accommodation design algorithms that can heuristically establish wavelength paths (WPs) or virtual wavelength paths (VWPs) in the network, where each link is composed of multiple fibers. These algorithms minimize the average number of fibers (in other words, cross-connect ports) handled at the WP/VWP cross-connect nodes and enable us to obtain the required OP cross-connect (OPXC) system scale at each node in WP/VWP networks. Algorithms that consider failure restoration are also proposed. Some WP/VWP accommodation designs over a polygrid network are simulated using the proposed algorithms. The difference between the WP and VWP schemes in terms of the required OPXC system scale with and without considering failure restoration is quantitatively evaluated for the first time.