SONET - (Synchronous Optical Network) - A family of digital transmission rates and standards that use fiber optics. https://en.wikipedia.org/wiki/SONET
Structure of SONET/SDH signals
Framing
SONET structures
Transport overhead
Synchronous payload envelope

SONET/SDH and relationship to 10 Gigabit Ethernet
SONET/SDH data rates
SONET physical layer
SONET/SDH Network Management Protocols
SONET equipment

SONET regenerator
SONET add-drop multiplexer (ADM)
SONET Digital Cross Connect system

SONET Network Architectures
SONET synchronization
Next-generation SDH
https://en.wikipedia.org/wiki/SONET