Wataru Imajuku

GMPLS-based photonic multilayer router (Hikari router) architecture: an overview of traffic engineering and signaling technology

A new extended signaling and traffic engineering method for the GMPLS-based photonic and electrical multilayer router (Hikari router) is proposed. The method allows dynamic optical network management and photonic signal recovery, such as regeneration, reshaping, etc., to be realized adaptively. Wavelength conversion is also adaptive, which reduces network cost. Multilayer traffic engineering, which yields the dynamic cooperation of IP and photonic layers, is described to provide IP services cost effectively. To realize multilayer traffic engineering, we propose the OSPF extension, which advertises both the number of total wavelengths and the number of unused wavelengths, and the RSVP-TE extension, which minimizes the number of wavelength conversions needed. In addition, this paper proposes a heuristics-based multilayer topology design scheme that uses IP traffic measurements in a generalized multi-protocol label switch (GMPLS). The proposed scheme yields the optical label switch path (OLSP) network topology, that is, OLSP placement, that minimizes network cost, in response to fluctuations in IP traffic demand. In other words, the OLSP network topology is dynamically reconfigured to match IP traffic demand. Networks are reconfigured by the proposed scheme so as to utilize network resources in the most cost effective manner.

Dynamic multilayer routing schemes in GMPLS-based IP+optical networks

This article presents two dynamic multilayer routing policies implemented in the photonic MPLS router developed by NTT for IP+optical generalized MPLS networks. According to IP traffic requests, wavelength paths called lambda label switched paths are set up and released in a distributed manner based on GMPLS routing and signaling protocols. Both dynamic routing policies first try to allocate a newly requested electrical path to an existing optical path that directly connects the source and destination nodes. If such a path is not available, the two policies employ different procedures. Policy 1 tries to find available existing optical paths with two or more hops that connect the source and destination nodes. Policy 2 tries to establish a new one-hop optical path between source and destination nodes. The performances of the two routing policies are evaluated. Simulation results suggest that policy 2 outperforms policy 1 if p is large, where p is the number of packet-switching-capable ports; the reverse is true only if p is small. We observe that p is the key factor in choosing the most appropriate routing policy. We also describe items that need to be standardized in the IETF to effectively achieve multilayer traffic engineering.

Bandwidth Squeezed Restoration in Spectrum-Sliced Elastic Optical Path Networks (SLICE)

With the continuing growth in the amount of backbone traffic, improving the cost-effectiveness and ensuring survivability of the underlying optical networks are very important problems facing network service providers today. In this paper, we propose a bandwidth squeezed restoration (BSR) scheme in our recently proposed spectrum-sliced elastic optical path network (SLICE). The proposed BSR takes advantage of elastic bandwidth variation in the optical paths of SLICE. It enables spectrally efficient and highly survivable network recovery for best-effort traffic as well as bandwidth guaranteed traffic, while satisfying the service level specifications required from the client layer networks. We discuss the necessary interworking architectures between the optical path layer and client layer in the BSR in SLICE. We also present a control framework that achieves flexible bandwidth assignment as well as BSR of optical paths in SLICE. Finally, we describe an implementation example of a control plane using generalized multi-protocol label switching (GMPLS).

G-lambda: coordination of a grid scheduler and lambda path service over GMPLS

A vertical coordination between computing resource scheduler and network resource scheduler for Grid-based applications is described. The network resource management system virtualizes and schedules network resources to inter-work with Grid resource scheduler through Web-services interface.

Distributed virtual network topology control mechanism in GMPLS-based multiregion networks

This paper proposes a distributed virtual network topology (VNT) reconfiguration method for Internet Protocol over a wavelength-division-multiplexing network under dynamic traffic demand. We have developed a simple heuristic algorithm for calculating the VNT for distributed control. A generalized multiprotocol label switching (GMPLS)-based routing protocol has been developed. The VNT is quickly reconfigured by setting up and/or tearing down lightpaths using a GMPLS signaling protocol. Traffic demand is measured at the ingress node and advertised by the extended GMPLS routing protocol. Performance of the proposed method is investigated using variable traffic model.

MORSA: A Multi-objective Resource Scheduling Algorithm for NFV Infrastructure

Capital expenditure (CAPEX) and operating expenses (OPEX) have been practical concerns for telecommunication companies, and Network Function Virtualization (NFV) has attracted significant attention in recent years. However, the NFV Infrastructure (NFVI) includes a wide variety of resource types and stakeholders. Hence, there is still a need for the existing resource scheduling approaches, but they are no longer sufficient. In this paper, we propose a Multi-objective Resource Scheduling Algorithm (MORSA) to optimize the NFVI resources. In the development of the MORSA, we designed a plug-in architecture to satisfy various requirements related to NFVI resources and stakeholder policies. The MORSA allows the NFVI Resource Scheduler to optimize simultaneously the combination of possibly conflicting objectives with multifaceted constraints in complex real world situations. Evaluation results show that the MORSA obtains approximate solutions among conflicting objectives in a reasonable computation time.

Linewidth narrowing and optical phase control of mode-locked semiconductor ring laser employing optical injection locking

The linewidth of the individual modes of an actively mode-locked extended-ring-cavity semiconductor laser is reduced from a free running linewidth of over 200-20 kHz by the injection of a narrow linewidth continuous-wave (CW) light. The optical phase of the injection-locked pulses can be controlled by adjusting the free-running optical frequency of the semiconductor ring laser. The variation in the optical phase of the output pulses versus the change of the free-running optical frequency is evaluated to be 0.57/spl pi/ radians within the locking range of about 96 MHz by observing temporal shape of the beat signal formed between output pulses and CW injection light.

Heuristic multi-layer optimum topology design scheme based on traffic measurement for IP + photonic networks

This paper presented a heuristic-based multilayer topology design scheme, called EBXCQ, for IP photonic networks. By monitoring IP traffic loads, photonic MPLS routers are controlled to dynamically change the network configuration to efficiently utilize the network resources in a distributed manner.

Reduction of fiber-nonlinearity-enhanced amplifier noise by means of phase-sensitive amplifiers

In optical fiber transmission systems near the zero-dispersion wavelength that use in-line erbium-doped fiber amplifiers (EDFAs), the enhancement of optical amplifier noise caused by four-wave mixing (FWM) in transmission fibers degrades signal-to-noise ratio (SNR) excessively. We theoretically show that the enhancement of amplifier noise by the FWM in transmission fibers can be effectively eliminated by implementing in-line phase-sensitive amplifiers (PSAs). Small-signal analysis of the nonlinear Schrödinger equation shows that the transmission distance limited by the SNR of an in-line PSA system is expanded four times more than that of an in-line EDFA system.

Evaluation of amount of equipment on single-layer optical path networks managing multigranularity optical paths

The authors propose novel nongrooming, optical path cross-connect (OXC), single-layer optical path (OP) networks that can route multigranularity optical paths with reduced optical switch (OSW) size. Since the multigranularity OPs are handled in one OP layer, the configuration and path administration of the OXCs become simple. The authors evaluate the network topology dependency of the network elements, i.e., the required number of OSW ports and fibers in networks consisting of 36 fixed nodes with different network topologies as well as that of a 16-OXC, 25-link NSFNET. The proposed networks require 60% fewer OSW ports, enabling efficient link resource utilization. A 60% reduction in total network cost is also confirmed.