Itaru Nishioka

Hierarchical routing in layered ring and mesh optical networks

We consider hierarchical optical networks with different granularities of paths (wavelengths and wavebands). We introduce classification layers for routing models in these networks (separated and integrated routing, homogeneous and heterogeneous networks, online and offline routing). We also propose and analyze two heuristic routing and aggregation algorithms (online and offline) to be used for homogeneous networks in the separate routing framework. The analysis is based on ring topology; its results are supported by simulations of large scale networks (Europe and USA). These simulations demonstrate a significant cost reduction achieved by employing hierarchical routing (from 33% in the online algorithm to almost 60% in the offline one).

Experimental Demonstration of Highly Resilient Wavelength-Switched Optical Networks With a Multivendor Interoperable GMPLS Control Plane

The backbone infrastructure for providing carrier-class services, such as a wavelength-switched optical network (WSON), usually involves equipment from multiple vendors. For intelligent path control in the WSON, it is highly desirable to introduce a unified generalized multiprotocol label switching (GMPLS) control plane, which is beneficial for reducing the operational cost and facilitating the dynamic service recovery. However, the interoperability issue of GMPLS-enabled WSON among multiple vendors has not been investigated to date, preventing its wide deployment in an actual operational scenario. Accordingly, in this paper, we experimentally present a highly resilient WSON with a multivendor interoperable GMPLS control plane. We successfully verify the interworking of the GMPLS control plane and wavelength-switching equipment from multiple vendors, and experimentally present dynamic wavelength path control and dynamic lightpath recovery from single-link failures that occur at different times and multiple link failures that occur simultaneously on a multivendor WSON testbed with both control and data planes. To the best of our knowledge, the interoperability trial of GMPLS-controlled WSON is a world first.

Nationwide GMPLS field trial using different types (MPLS/TDM/lambda) of switching capable equipment from multiple vendors

A GMPLS field trial using different types of switching capable equipments from multiple vendors was conducted on a nationwide scale and the setup of MPLS/TDM/lambda hierarchical LSP was successfully achieved ensuring GMPLS interoperability in a multilayer for the first time.

Ultra-small one-chip color-less multiplexer/demultiplexer using silicon photonic circuit

Using silicon waveguides, an arrayed waveguide grating and switches are integrated into one chip. Low-power and fast-speed reconfigurability of optical paths within a 2-mm device is demonstrated.

Multi-domain ASON/GMPLS network operation: current status and future evolution

This paper describes clarifications and comparisons of routing models for multi-domain optical networks as well as the current status and future perspective for ASON/GMPLS technologies. The three routing models, the per-domain routing, the ASON hierarchical routing, and the PCE-based routing, have been being standardized for the ASON/GMPLS multi-domain networks. In this paper, we compare these three routing models in terms of path computation capabilities, on-line multiple path planning capability and inter-domain confidentiality. According to our analyses, the PCE-based routing and the ASON hierarchical routing models have rich path computation capabilities enough for multi-domain ASON/GMPLS network operation, while the per-domain routing does not provide much capabilities. One of the significant issues left for the ASON hierarchical routing model is an appropriate abstraction mechanism which strongly affects the path computation capabilities and inter-domain confidentiality. In addition to the sufficient path computation capabilities, the PCE-based routing model offers the on-line bulk optimization for multiple requests. Therefore, we concluded that the PCE-based routing is the most suitable for multi-domain ASON/GMPLS networks.

Field Trial of Signaling Interworking of Multi-carrier ASON/GMPLS Network Domains

A seamless end-to-end call set up over multi-carrier ASON and GMPLS network domains was successfully achieved. Interworking of two ASON network domains and five GMPLS network domains was demonstrated on a nationwide scale.

A multi-area MPLS/GMPLS interoperability trial over ROADM/OXC network

This article describes the first multi-area multiprotocol label switching and generalized MPLS interoperability trial over a reconfigurable optical add/drop multiplexer and optical cross-connect network. The interoperability trial demonstrated the routing of label switched paths over a multi-area GMPLS controlled ROADM/OXC network and the control of Ethernet over MPLS transport service on top of the GMPLS network. The trial was conducted using various network elements provided by 14 institutions and was carried out in Tokyo and Virginia. This article introduces the motivation for the trial, technical issues related to controlling multiarea MPLS/GMPLS networks, test network topology, and experimental results. The results show that the interior gateway routing protocol based multi-area routing architecture is a promising solution for the nationwide deployment of GMPLS networks within a carrier domain. In addition, this article discusses the technical issues of routing constraints in ROADM/OXC networks and the limit of multiarea routing without the Path Computation Element Protocol.

PCE-based Scalable Dynamic Path Control for Large-scale Photonic Networks

This paper proposes an inter-domain path control system based on PCE (Path Computation Element) for large-scale photonic networks, especially for a photonic network across over multiple carrier domains. We discuss the overall architecture of multi-domain optical network control system. The system utilizes maximum flow information in path computation and Path Key scheme in signaling, which improve the load-balancing and the confidentiality of the inside information for the route computation and the path provisioning among different carriers. We also provide measured performance results for inter-domain path computation and path setups using global optimization scheme, estimating the path provisioning time at the network scale dependency with the route computation time and the signaling time. As a result, we show its applicability to a 1000-node scale photonic network.

Multi-area MPLS/GMPLS Interoperability Trial Over 14-Vendor Packet/TDM/ROADM/OXC Network

A multi-area MPLS/GMPLS interoperability trial was successfully conducted using various types of network elements from 14 vendors for the first time. The results show that the interior gateway routing protocol based multi-area routing architecture is a promising solution to achieve nationwide deployment of GMPLS networks within a carrier domain.

Optical network control challenges

This paper discusses two challenges, failure recovery enhancement and scalability enhancement, on optical network control plane. These challenges enable us to provide optical networks with high reliability and lower operational cost.