Abstract

Optical layer protection is an attractive method for protecting client signals in an optical network. Protection switching using optical switches promises considerable cost savings relative to electronic protection switching, in addition to offering advantages such as wavelength and bit rate transparency.¹ One of the more difficult issues in implementing optical protection switching has been to find reliable performance monitoring schemes. A fundamental problem is that a certain minimum time is required in order to reliably detect failures. This detection time is not much different in the optical layer compared to the client layer. It is therefore difficult for the optical layer to switch before the client layer detects a failure and initiates its own protection.² The only solution to this challenge is to devise a monitoring scheme that enables advance warning of potential failure modes.

© 2002 Optical Society of America