We investigate virtual-network-function placement and scheduling problem in optical datacenter networks, considering the installation/de-installation latency of VNF and the rapid variation of low-latency-demands. The proposed scheme achieves low blocking probability, latency, and spectrum resource consumption.
Future access network architectures should exhibit reliability while providing broadband Internet services. Progress on research and development of reliable wired and wireless access networks is discussed in this paper. Some emerging access network architectures and their reliability issues are explained.
We investigate new connection-provisioning algorithms to efficiently provide signal-quality-guaranteed connections in an all-optical WDM mesh network. In the all-optical network, signal degradations incurred by non-ideal transmission medium accumulate along a lightpath. When the signal degradation reaches a certain level, the connection is not usable and is blocked due to transmission impairments in the physical layer. To ensure high service quality of provisioned connections, it is essential to develop intelligent routing and wavelength assignment (RWA) algorithms which can combat the effects of impairments when setting up a connection. For this purpose, we propose two impairment-aware RWA algorithms, namely impairment-aware best-path (IABP) algorithm and impairment-aware first-fit (IAFF) algorithm. The optical signal-to-noise raito (OSNR) requirement and polarization mode dispersion (PMD) effect are used as signal-quality constraints to avoid setting up a connection with unacceptable quality due to the effects of transmission impairments. With the signal-quality consideration, as compared to algorithms that are not impairment aware in a realistic optical network, our proposed impairment-aware algorithms efficiently provide signal-quality-guaranteed connection while significantly reducing connection-blocking probability, better utilizing network resources, and having a reasonable computational requirement. Also, the effect of channel bit rate is studied in this paper.
Wavelength-division multiplexing (WDM) is the promising technology to meet the rapid growth of Internet traffic. The next-generation optical WDM networks will have the capability of real-time provisioning of network capacity, providing interoperability between different optical and electronic networks, etc. An unified control plane that incorporates these desirable features is being designed and developed. Traffic grooming is a very important problem whose solution will enable us to fully develop such a control plane for next-generation optical networks. In this work, we study the network architectures for grooming-capable WDM networks and propose a routing algorithm that enables a WDM network to support dynamic grooming of traffic streams of different capacity granularities. Network performance, based on various node architectures, is investigated via simulations.
We propose a novel optical-electrical hybrid contention-resolution scheme for optical packet-switched networks. This scheme exploits both electrical buffering at the ingress nodes and optical contention resolutions at the core nodes. It significantly improves the network's performance with a simple node architecture. By employing self-similar packet traffic with typical IP packet-size distribution, we demonstrate a packet-loss rate of less than 0.01 with average offered transmitter load up to 0.6 for a representative telecom network. Our results also show that the use of electrical buffering at the edge does not introduce any significant latency.
Intelligent methods for automatic protection and restoration are critical in optical transport mesh networks. This paper discusses the problem of quality of service (QoS)-based protection in term of the protection-switching time and availability for end-to-end lightpaths in a WDM mesh network. We analyze the backup lightpath-sharing problem in such networks and study the correlation of the working lightpaths and its impact to the sharing of their backup lightpaths. We present a multi-protocol-label-switching (MPLS) control-based fully distributed algorithm to solve the protection problem. The proposed algorithm includes intelligent and fully automatic procedures to set up, take down, activate, restore, and manage backup lightpaths. It greatly reduces the required resources for protection by allowing the sharing of network resources by multiple backup lightpaths. At the same time, it guarantees, if possible, to satisfy the availability requirement even with resource sharing by taking the correlation of working lightpaths into consideration when deciding backup lightpaths. A simple analysis of the proposed algorithm in terms of computation, time, and message complexity indicates that the implementation of the algorithm is practical. The illustrative studies that compare the performance of 1:1, unlimited sharing, and QoS-based sharing backup algorithms indicates that QoS-based sharing achieves comparable performance as unlimited sharing, which is much better than the 1:1 backup scheme in terms of connection blocking probability, average number of connections in the network for a given offered load, and network-resource utilization.
This study investigates the problem of fault management in a wavelength-division multiplexing (WDM)-based optical mesh network in which failures occur due to fiber cuts. In reality, bundles of fibers often get cut at the same time due to construction or destructive natural events, such as earthquakes. Fibers laid down in the same duct have a significant probability to fail at the same time. If two fibers reside in the same cable (bundle of fibers) or the same duct, we say that these two fibers are in the same Shared Risk Group (SRG). When path protection is employed, we require the primary path and the backup path to be SRG-disjoint, so that the network is survivable under single-SRG failures. Moreover, if two primary paths go through any common SRG, their backup paths cannot share wavelengths on common links. This study addresses the routing and wavelength-assignment problem in a network with path protection under SRG constraints. Off-line algorithms for static traffic is developed to combat single-SRG failures. The objective is to minimize total number of wavelengths used on all the links in the network. Both Integer Linear Programs (ILPs) and heuristic algorithms are presented and their performances are compared through numerical examples.
This paper presents a comparative study of contention-resolution schemes based on wavelength, time, and space domains in an unslotted optical packet-switched network with a large irregular mesh topology consisted of 15 nodes. For the first time, to the best of our knowledge, we investigated the effect of selective deflection and limited wavelength conversion. Features and performances of different combinational schemes are listed and compared. While simulation results show the effectiveness of wavelength conversion for resolving contentions over optical buffering and space deflection, physical explanations of the different effectiveness in resolving contentions of these schemes are also discussed.
SIMON is an object-oriented event-driven simulation package implemented in C++ which incorporates optical device characteristics in the measurement of network-level blocking statistics. SIMON is suitable for studying the performance of large wavelength-routed optical networks, in which a call is set up in the network for a specific duration on a pre- determined lightpath. Currently the physical-layer models allow for modeling phenomena such as signal attenuation in fiber and other components, amplifier gain saturation, and homowavelength crosstalk in switches. Simulation experiments can be performed with a user-specified bit-error rate limit, which must be satisfied by any call set up in the network.
We develop algorithms for the design of optical packet-switched networks. These algorithms are aimed at upgrading an existing fiber-based, network infrastructure, such as the NSFNET backbone, by using wavelength division multiplexing (WDM) technology. The network architecture employs wavelength-routing optical switches which enable the establishment of all-optical, WDM channels, called lightpaths. A set of lightpaths may be used as a virtual topology over which packet-switched traffic may be transported ina store-and-forward manner. The packet forwarding is done by electronic packet routers which are attached to the wavelength-routing optical switches. This paper examines issues related to the upgrading of an existing fiber-based, packet-switched, electronic network to accommodate WDM, and to the optimal choice of the virtual topology based on changing traffic demands. We demonstrate how the total information carrying capacity of the network can be enhanced by using WDM.
A single-hop wavelength division multiplexing (WDM) based local lightwave network employing a passive star topology is considered. The system consists of a single control channel and a number of data channels. Each station is equipped with a transmitter and a receiver, both of which are tunable over all the channels. Nodes employ the control channel to arbitrate (coordinate) their access to the data channels. The attractiveness of this architecture is its extreme simplicity. We have previously proposed a Receiver Collision Avoidance (RCA) protocol for such a system in which all nodes are equidistant from the passive star. Under the RCA protocol, access to the control channel is provided via a variation of slotted ALOHA, which includes a simple mechanism that can dynamically detect and avoid receiver collisions. The protocol is scalable and can support a large number of bursty nodes with a relatively small number of data channels. In this paper, we consider an extended RCA protocol (E-RCA) to incorporate nonuniform distances, while maintaining all of the protocol's original attractive features. The analytical model for the E-RCA protocol is difficult to formulate; therefore, extensive simulations were conducted under various distance distributions. Results indicate that the E-RCA protocol performs almost as well as the RCA protocol under the same average distance conditions. Also, like the RCA protocol, the E-RCA protocol is simple, based on practical assumptions, and can be readily implemented with current lightwave technology.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.