ector Laser," IEEE Journal of Quantum Electronics QE-23, 903 (1987); C. J. Chang-Hasnain, "Vertical Cavity Surface Emitting Laser," IEEE Journal of Selected Topics on Optics Primer Quantum Electronics (June 2000): 978 ff; and P. Zorabedian and W.R. Trutna, "External Cavity Diode Laser," Optics Letters 13 (1988): 826 ff. 12. Composition: Indium-Gallium-Arsenide (InGaAs). 13. Composition: Germanium (Ge). 14. R. A. Barry, "Intelligent Optical Networking Year 2001: A Practical Perspective," NGN 2001 Proceedings, 2001. 15. Major new physics-related issues impact operation at the OC-768 rate. 16. Some material here is based in part on Stephen Koffler and Lori Franklin, "Optical Networking: A Focus on the Metro Opportunity," First Union Securities, New York, NY, June 2000. 17. This figure was adapted from Avanex Corporation Promotional Material, www.avanex.com. 18. This is based on Adva Optical Promotional Material, www.advaoptical.com; the rest of the section is from the same source. 19. C. Metz, "A Survey of Advanced Internet Protocols," Cisco Educational Materials, 2001. This page intentionally left blank. CHAPTER Traditional SONET Architectures Chapter 3 We open this chapter with a review of the evolution of optical networks in general and the Synchronous Optical Network (SONET) in particular dur- ing the past 15 years. The rest of the chapter tackles technical aspects of SONET from the perspective of broadband metro applications and resiliency.¹ 3.1 The Evolution of Optical Networking The deployment of fiber-optic facilities began in the early 1980s. Up to that point, the telecommunications infrastructure was built on a hierarchy that was derived from and suited to copper/coaxial transmission systems. Throughout the 1980s, these fiber-optic systems were vendor proprietary, notably based on AT&T (now Lucent) technology in the North American market. Other manufacturers introduced systems in Europe and Japan; however, none of the systems interoperated with one another. Starting in the mid-1980s, and more SO in the lat