Useful URL's
 
  Cisco - Optical Networking APS (Automatic Protection Switching)
  Cisco - Optical Networking SDH (Synchronous Digital Hierarchy)
  Cisco - Optical Networking SONET (Synchronous Optical Network)
  Cisco - Optical Networking SRP/DPT (Spatial Reuse Protocol/Dynamic Packet Transport)
  Cisco - Optical Networking Intro to DWDM/WDM (Dense Wave Division Multiplexing/Wave Division Multiplexing)
  Cisco - Optical Networking Intro to CWDM (Course Wave Division Multiplexing)