optical networks
DESCRIPTION
Optical Networks. Rainbow for Communications. Medium Sharing. Time Division Multiplexing (TDM) Frequency Division Multiplexing In the optical domain, Wavelength Division Multiplexing. Time Division Multiplexing. Wavelength Division Multiplexing. Principle. Shared Medium. Potential. - PowerPoint PPT PresentationTRANSCRIPT
Optical NetworksOptical Networks
Rainbow for Communications
Medium SharingMedium Sharing
Time Division Multiplexing (TDM)
Frequency Division Multiplexing
In the optical domain, – Wavelength Division Multiplexing
Time Division MultiplexingTime Division Multiplexing
Wavelength Division MultiplexingWavelength Division Multiplexing
PrinciplePrinciple
Shared Medium
PotentialPotential
Today: each wavelength may carry data rates from 2.5 to 10 Gbps. Commercial systems support up to 160 wavelengths on one strand.
Soon, 1000 ?
Wavelength RoutingWavelength Routing
For any two communicating nodes, establish a lightpath (using the same wavelength all along the path).
The Routing and Wavelength The Routing and Wavelength Assignment Problem (RWA)Assignment Problem (RWA)
NP Problem!
RWA For Different NetworksRWA For Different Networks
Wavelength-continuity constraint: lightpath with the same wavelength from source to destination
Wavelength-convertible networks: All or some nodes are allowed to convert wavelengths (switch wavelength).
RWA Types of ProblemsRWA Types of Problems
Static RWA
Sequential RWA
Dynamic RWA
Strategy to Solve RWAStrategy to Solve RWA
Break RWA:– Routing problem : Dijkstra or Bellman-Ford
– Wavelength assignment: a suggestion?
How About Grooming?How About Grooming?
Grooming adds another dimension to the problem:– Mix together some low rate traffic flows into
one flow to occupy one wavelength.
Switching in Optical NetworksSwitching in Optical Networks
Based on “Techniques for Optical Packet Switching and Optical Burst Switching”,
L. Xu, H.G. Perros, and G. Rouskas
Packet Coding TechniquesPacket Coding Techniques
Bit serial coding
Bit parallel:
Out of band signalling
Bit Serial CodingBit Serial Coding
Optical code-division multiplexing (each bit carries routing information)
Optical pulse interval : header and payload are separate, but transmitted at same rate
Mixed rate techniques: header and payload are separate, but header transmitted slower
Bit Parallel and Out of band Sig.Bit Parallel and Out of band Sig.
Bit parallel: bits are sent in parallel on different wavelength
Out-of-band signalling: – SCM (Subcarrier Multiplexing): header is sent
on electrical carrier.– Dual wavelength: header and payload are sent
on different wavelength
How to Solve Contention?How to Solve Contention?
Optical StoringOptical Storing
Optical Buffering : using optical delay lines
Wavelength Domain: Packet scheduling becomes similar to multiprocessor scheduling
Deflection routing: send out on any available output port