A Review on Importance of DWDM Technology in Optical Networking

Optical communication uses light signals for transmitting information from source to destination. Optical fiber communication has been more popular for long-distance data transfer in recent years due to various benefits such as low loss, low cost, simple amplification, minimal interference, and lightweight. A simple optical telecommunication system consists of a transmitter, a medium, and a receiver. Wavelength Division Multiplexing (WDM) is a significant improvement in optical communication. WDM is basically used for improving spectral efficiency and to handle more data from several clients. Normal WDM, CWDM, and DWDM are three types of WDM technology. DWDM uses the most denser optical channels in optical networking. Complete detail about all types of WDM is given. The optical spectrum used in the transmission of light signals is also discussed.

WDM Access Networks

In TDM PONs, or simply PONs, the transmission capacity of optical fibers remains under-utilized with single-wavelength transmissions for both upstream and downstream traffic. Use of WDM transmission in PONs can significantly enhance the overall network capacity and coverage area. WDM transmission in PONs can be realized in several ways, such as by using WDM exclusively or combining WDM with TDM, leading to WDM PONs and TDM-WDM PONs (TWDM PONs). This chapter gives several candidate physical configurations to realize WDM and TWDM PONs, and describes some useful dynamic wavelength-bandwidth allocation (DWBA) schemes for the latter. We also briefly discuss the needs of open access to the PON-based access networks for the various stakeholders, such as service providers and network providers. Finally, we describe briefly the roles of optical networking in the access segment of mobile networks. (135 words)

WDM Metro Networks

With increasing traffic, legacy SONET/SDH-metro rings have mostly been upgraded using point-to-point WDM (PPWDM) transmission. For cost-effective realization, WDM metro networks also employ wavelength-routed optical networking (WRON), where a wavelength is bypassed optically at intermediate nodes. Metro networks are generally split into core and edge rings, with the metro-core ring interfacing with the long-haul backbone and the metro-edge ring interconnecting the metro-core ring with the access segment. The PPWDM/WRON transmission is employed with each wavelength using circuit-switched SONET/SDH transmission, though the metro-edge rings can also use packet-switching to enhance bandwidth utilization with bursty traffic from the access segment. In this chapter, we consider first WDM metro networks using PPWDM/WRON-based rings and present their design methodologies using LP-based and heuristic schemes. We describe some packet-switched WDM ring testbeds and examine the possible improvement in bandwidth utilization therein, as compared to the circuit-switched WRON rings. (143 words)

Optical Networks: An Overview

We present an overview of optical networks, beginning with a background of today’s telecommunication networks and the roles of optical fibers therein. Next, we describe the chronology of developments in telecommunication networks starting from the days of public-switched telephone network (PSTN) offering ‘plain old telephone service’ as the basic service, followed by the divestiture of Bell Laboratories and subsequent developments of the demonopolized regime of telecommunication networks with multiple services offered to users by the same network providers. Then we describe the salient features of the two generations of optical networks for various network segments, including single-wavelength and WDM-based LANs/MANs, accesses networks, metro and long-haul networks, datacenters, and elastic optical networks. Finally, we discuss briefly the possible network architectures with the evolving optical-networking technologies. (124 words)

Design and Analysis of AWG and FDL-Based Optical Switch in Data Centre Network

Optical networking technologies can play a significant role in the realization of grid and data centre systems. The new and developing internet applications are progressively becoming high performance and network based, and the performance of these applications are depending on the optical network and cloud computing services. In this chapter, the authors discuss the capabilities of optical transmission and the switching techniques. An AWG-based optical switch is discussed in the chapter and the performance of switch is measured in physical and network layer parameters. Design modifications in the switch is suggested, for improving the performance of switch. The overall performance of switch is also measured when the switch is placed into the network where cascading of two or more switches are required.