Optical layer survivability: A services perspective

This article provides a perspective on optical layer protection and restora tion based on the services offered by carriers using the optical layer. Thi s is different from other viewpoints that provide a taxonomy of protection techniques in a more abstract fashion for the purposes of standardization. The latter viewpoints are mostly based on the classification adopted in the SONET/SDH standards. In contrast, taking a services-based view provides a way to distinguish between protection schemes based on implementation costs and the associated services enabled by the protection scheme.