Overall introduction to SONET

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SONET / SDH
(Synchronous Optical Networking /
Synchronous Digital Hierarchy)
By
Akash Kumar Dhameja,
K12270
BCA, IV sem.

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INDEX
• Introduction
• Architecture SONET System
• SONET Frame
• SONET Layers
• SONET Network
• Advantage

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• Synchronous Optical Networking (SONET) and
Synchronous Digital Hierarchy (SDH) are
standardized protocols that transfer multiple digital
bit streams synchronously over optical fibre using
lasers.
INTRODUCTION

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• Both SDH and SONET are widely used today: SONET in
the United States and Canada, and SDH in the rest of the
world.
• The SDH standard was originally defined by the
European Telecommunications Standards Institute
(ETSI), and is formalized as International
Telecommunications Union (ITU) standards
G.707,G.783,G.784,and G.803.The SONET standard was
defined by Telcordia and American National Standards
Institute (ANSI) standard T1.105.
CONTINUE….

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Signals
Devices
Connections
ARCHITECTURE OF SONET SYSTEM

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Signals:
• Electrical signaling levels called synchronous transport
signals (STSs).
• The corresponding optical signals are called optical
carriers (OCs).
• SDH specifies a similar system called a synchronous
transport module (STM).
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7. Career Point CaresSONET RATES
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Devices:
• STS multiplexers
• STS DE multiplexers
• Regenerators
• add/drop multiplexers
• Terminals.

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A simple network using SONET equipment

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STS Multiplexer/ DE multiplexer:
• Provide the interface between an electrical tributary
network and the optical network.
• For example, three STS-1 signals (channels) can be
combined into one STS-3 signal (channel), four
STS-3s can be multiplexed into one STS-12, and so on.
• STS multiplexer multiplexes an electrical signal into
corresponding Optical signal.
• STS DE multiplexer DE multiplexes an optical
OC signal into corresponding electric signals.

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STS multiplexing/de-multiplexing
Note: In SONET, all clocks in the network are locked to
a master clock.

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Byte interleaving

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Regenerator
• Regenerator is a repeater
• Extend the length of the links

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SONET SYSTEM
Add/drop Multiplexer
• Add/drop multiplexers allow insertion and
extraction of signals.

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Terminals
• Device that uses the services of a SONET
network.

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Connections:
• Sections(connecting two neighboring devices).
• Lines(two multiplexers).
• Paths(end-to-end portion ).

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SONET LAYERs
The SONET standard includes four functional
layers:
• Path
• Line
• Section
• Photonic.

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Path:
• The path layer is responsible for the movement of
a signal from its optical source to its optical
destination.
Line:
• The line layer is responsible for the movement of
a signal across a physical line
• STS multiplexers and add/drop multiplexers
provide line layer functions.

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Section Layer:
• Section layer overhead is added to the
frame at this layer and control errors.
Photonic Layer:
• It includes physical specifications for the
optical fiber channel.

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CONTINUE….

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• Each synchronous transfer signal STS-n is composed
of 8000 frames. Each frame is a two-dimensional
matrix of bytes with 9 rows by 90 × n columns.
• Each byte in a SONET frame can carry a digitized
voice channel.
SONET FRAME

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STS-1 and an STS-n frame

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• Bytes are transmitted from the left to the right and top
to the bottom.
• STS-n signal is transmitted at a fixed rate of 8000
frames per second.
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Ques: Find the data rate of an STS-1 signal.
Solution:
STS-1, like other STS signals, sends 8000 frames per
second. Each STS-1 frame is made of 9 by (1 × 90) bytes.
Each byte is made of 8 bits. The data rate is
EXAMPLE 1

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Ques: Find the data rate of an STS-3 signal.
Solution
STS-3, like other STS signals, sends 8000 frames per
second. Each STS-3 frame is made of 9 by (3 × 90) bytes.
Each byte is made of 8 bits. The data rate is
EXAMPLE 2

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Ques: What is the duration of an STS-1 frame? STS-3
frame? STS-n frame?
• Solution
In SONET, 8000 frames are sent per second. This
means that the duration of an STS-1, STS-3, or STS-n
frame is the same and equal to 1/8000 s, or 125 μs.
Note: In SONET, the duration of any frame is 125
μs.
EXAMPLE 3

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Using SONET equipment, we can create a SONET
network that can be used as a high-speed backbone
carrying loads from other networks.
SONET NETWORK

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Linear Network
Point-to-Point:
A point-to-point network is normally made of an STS
multiplexer, an STS DE multiplexer, and zero or more
regenerators with no add/drop multiplexers
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Multipoint:
A multipoint network uses ADMs to allow
communications between several terminals.
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One-Plus-One APS
• To create protection against failure in linear networks,
SONET defines automatic protection switching
(APS).
• In this scheme, there are normally two lines: one
working line and one protection line. Both lines are
active all the time.
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One-to-One APS
• The data are normally sent on the working line until it
fails.
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One-to-Many APS
• This scheme is similar to the one-to-one scheme
except that there is only one protection line for many
working lines.
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Ring Network
UPSR:
A unidirectional path switching ring (UPSR) is a
unidirectional network with two rings.
SONET NETWORK

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BLSR:
Another alternative in a SONET ring network is a
bidirectional line switching ring (BLSR).
CONTINUE….

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Mesh Network:
When the traffic in a ring increases, we need to upgrade.
CONTINUE….

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ADVANTAGE
Reduced network
complexity
Protection
Bandwidth
High data
rate.
Flexible
Topologies
Efficient
management of
bandwidth

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• http://searchnetworking.techtarget.com
• http://www.fiberoptic.com
• https://en.wikipedia.org
• https://www.slideshare.net
• https://www.techwalla.com
• http://mateoalejandro.weebly.com
REFRENCE

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Questions

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