Abstract
With the advent of 21st century, the exponential growth of Internet and the revolution in high bandwidth applications have created capacity demands that exceed traditional TDM limits. As a result, the once seemingly inexhaustible bandwidth promised by the deployment of optical fiber is being exhausted. To meet growing demands for bandwidth, a technology called Dense Wavelength Division Multiplexing (DWDM) has been developed that multiplies the capacity of a single fiber. This paper discusses the twin concept of optical networking and DWDM. The paper explains in detail the DWDM system and various components of an all-optical network like Optical Amplifiers, Optical Add/Drop Multiplexers, Optical Splitters etc The traditional IP over SONET architecture as it exists today is reviewed and the concept of transmitting raw IP packets over an optical layer which employs DWDM is put forth. The requirements for creating an all optical networks and issues pertaining such an evolution have been discussed here. This paper shall serve as a guide to the optical transport networks.
I. INTRODUCTION
In recent years, the explosive growth in Internet activities such as multimedia communications and networking has created an ever-increasing demand on network capacity, bandwidth and transmission rates. With this unprecedented development in telecommunication, many carriers are nearing one hundred percent capacity utilization across significant portions of their networks and finding that their estimates of fiber needs have been highly underestimated. Three methods exist for expanding capacity: 1) installing more cables, 2) increasing system bit rates to multiplex more signals or 3) wavelength division multiplexing (WDM). Installing more cables will prove to be a viable method in metropolitan areas, since fiber has become incredibly inexpensive and installation methods more efficient (like mass fusion splicing.) But this may not be the most cost effective, if conduit space is not available or major construction is required. Increasing system bit rate may not prove economical either.
VII. CONCLUSION
In this paper we have discussed various concepts that are integral to the development of the All-Optical Network. Various new technologies and principles governing a DWDM system were introduced. The existing system architecture was studied and a proposed optical layer was described in much detail. The basic concepts underlying an IP over DWDM system - like Network Management, Fault Tolerance, Interoperability, Optical Switching - were discussed at depth. . The IP/DWDM systems shall support the Open architecture & provide complete service transparency. The future of all-optical networks is plagued with many challenges. But, the commercial implementations for IP over DWDM are not far away. It opens the pathway to Terabit networking and unleashes the enormous bandwidth potential of the silica fiber. Hence, DWDM acts as the stepping stone towards a true optical networking era.
