Optical Networks
Fiber
•Provides the physical transport medium
Optical networks: Create the pipes
•WDM: Fast pipes for voice/data
•Optical amplification: Long pipes
IP Routers, ATM switches, SDH equipment: Fill the pipes
Operations Support System (OSS)
•Manage all aspects of the network
Evolution of Transmission Technology
•1st Generation: Copper is transmission medium
•2nd Generation: Optical Fiber (late 80s)
4Higher data rates; longer link lengths
•Dense Wavelength-Division Multiplexing (DWDM, 1994)
4Fiber exhaust forces DWDM
4Erbium-doped fiber amplifiers (EDFAs) lower DWDM transmission cost
•3rd Generation: Intelligent optical networking (1999)
4Routing and signaling for optical paths
Dense Wavelength-Division Multiplexing (DWDM)
DWDM Evolution
•Faster (higher speed per wave),
440 Gb/s on the horizon
•Thicker (more waves),
4160 waves possible today
•Longer (link lengths before regeneration)
4A few thousand km possible today
•160 waves at 10 Gb/s = 1.6 Tb/s
425 million simultaneous phone calls
45 million books per minute
IP over ATM
ATM over SONET
IP over ATM over SONET
Optical Pass-Through (Routing)
Intelligent Optical Networking
Optics is not merely a transmission technology
•Optics provides a flexible layer upon which to deliver network service
DWDM provides enormous link capacities
•DWDM: Physical layer of Intelligent Optical Network
Routing and signaling of optical paths
•Provides significant economies over conventional network architectures
•Enables revolutionary new services
42.5 Gb/s path from Bangalore to Boston, on demand!
SONET over Optical Layer
IP over SONET over Optical Layer
IP over Optical Layer
IP over Intelligent Optical Networks
§Establish high-speed optical layer connections (lightpaths)
§IP routers connected through lightpaths rather than fiber
§Switching (WDM crossconnects) add flexibility to the optical layer
•Flexible, potentially rich, topology at IP layer
