Survivable routing serves as one of the most important issues in optical backbone design. Due to the high data rates enabled by the wavelength division multiplexing technology, any interruption in the service results in the loss of a large amount of application data. Thus, making efforts to calculate and signal the protection resources promptly after the failure occurred would lead to an unacceptable high delay. As the main purpose of this chapter, the principles of pre-planned protection approaches in mesh optical backbone networks are discussed. The Shared Risk Link Group (SRLG) concept is introduced modeling physical and geographical dependency among seemingly unrelated link failures. Finally, methods are presented for calculating the exact end-to-end availability of a connection.
Shared Risk Link Group disjointness and geodiverse routing: A trade‐off between benefit and practical effort
