20-12-2012, 12:20 PM
Advances in Optical Networks:SONET
Advances in Optical.ppt (Size: 1.82 MB / Downloads: 102)
Fundamentals of Optical Networks
Fiber Optic Medium
Variants of Fiber and Optical Networks
Multiplexing Methods
Optical Network Equipment
Topologies of Optical Networks
Fiber Optic Medium
Core
Medium Where Light Travels
Cladding
Reflects Light Back into the Core
Buffer Coating
Protective Coating
Types of Multiplexing
Time Division Multiplexing (TDM)
Simplest Implementation
Uses Single Wavelength
Wavelength Division Multiplexing (WDM)
Complex Implementation
Multiple Wavelengths on a Single Fiber to Increase Bandwidth
Optical Network Equipment
Repeaters (OEO) & Amplifiers (EDFA)
Optical Crossconnects (OXC)
Photonic Switch with N Full-Duplex Ports
Optical Add-Drop Multiplexer (OADM)
Wavelengths Can Be Added and Removed from the Photonic Flow
Ex: Remove Traffic for Inbound T1 and Traffic for Outbound T1
Needed for WDM
Topologies
Ring Topology
Data Moves in One Direction around 1st Ring
If Failure Occurs, Traffic is Rerouted in Opposite Direction on 2nd Ring
Each Ring is ½ Total Capacity
Self-Maintaining
Mesh Topology
Locations are Linked to 2 or More Other Locations
If a Link Fails, Traffic is Rerouted around the Failure
Requires Routes to be Established Before Failure
Telecom Terminology
Synchronous Optical Network (SONET)
Asynchronous Transfer Mode (ATM)
Digital Signal (DS)
Synchronous Transport Signal (STS)
Optical Carrier (OC)
Background of SONET
Conceived by MCI During the Mid-1980’s
Designed from the Ground-Up to Hasten the Adoption of Optical Technology
Capacity and Distance Increased Rapidly Due to Technological Developments
Increased Purity of Fiber Optic Cable
Longer Distance without Regeneration
Iron, Nickel, and Hydroxyl Ions Cause Impurities
1970’s 20dB/km Loss, Today .2 dB/km Loss
Description
Physical-Layer Standard
Four-Layer Protocol Stack
TDM Creates Synchronous Channels
Multiplex Many Types of Traffic into Uniform Streams onto Fiber Optic Cabling
Used Primarily as Backbone for ATM
Four-Layers of SONET
Photonic: STS Electrical Data is Converted into OC Light Pulses and Vice Versa
Section: Operates between Optical repeaters, Helping to Transmit STS Frames
Line: Synchronizes and Multiplexes Multiple Streams into One Stream, Invokes APS When Required
Path: Used for End-to-end Communications and Control
SONET Virtual Tributaries
SONET is Capable of Accommodating Large and Small Capacities
STS-1 Frame Payload Can be Sub-Divided to Create Virtual Tributaries (VT)
Services Below DS3 are Transported via VTs in SONET
VTs are Multiplexed to Reach Capacity of STS Payload