Table of Contents:

Definition and Overview

1. Current Metro Architectures

2. Metro Operational Requirements

3. Metro OADX Applications

4. OADX Architectures

5. The OADX Business Case

6. OADX Benefits

7. Summary

Self-Test

Glossary

PDF of this tutorial

Definition
Optical add/drop switches (OADXs) are advanced optical elements designed to increase the scalability and efficiency of a metro optical network while retaining compatibility with the legacy synchronous optical network (SONET) and synchronous digital hierarchy (SDH) architectures and while enabling new services based on Gigabit Ethernet and other services based on optical wavelengths.

Overview
With Internet traffic continuing to increase exponentially and enterprises seeking to consolidate data resources and leverage higher-bandwidth networking topologies, SONET/SDH networks in the metro can no longer accommodate the demand for today's customer growth rates. The current generation of optically enabled Ethernet and storage area networking (SAN) equipment has given enterprise users the ability to build enterprise metropolitan-area networks (MANs) using leased dark fiber to interconnect their metro sites. The advantage of such connections is a reduction in the complexity and cost of point-to-point data services for the end user. However, these dark fiber connections require long-term commitments on behalf of the enterprise customer and are unable to respond effectively to the dynamic nature of Internet protocol (IP) traffic, and thus result in inefficient use of bandwidth in relation to the total bit-rate capacity of the fiber-optic cable. While wavelength division multiplexing (WDM) can increase the overall capacity of the fiber link, today's systems only deal with point-to-point connections.

To accommodate the any-to-any connections of today's peer-based IP networks, the networks must be built with either an extensive mesh of pre-provisioned dedicated fiber links or a hierarchical switched network. In either instance, there are engineering and management complexities to solve for a scalable and cost-effective deployment. The current metro network requirements are favorable to solutions that offer a scalable, dynamic, and cost-effective wavelength shared infrastructure. This is where OADXs can provide solutions.