Sdh and Sonet

8/10/2019 Sdh and Sonet

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SDH / SONET

Engr. Zain Ul Abiden Akhtar

Assistant Professor - UCET

Telecommunication Systems

&

Applications


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SDH/SONET

SDH/SONET, created in the mid-1980s, is

the second generation of digital hierarchy.

Whereas PDH involves a lot of overheadbecause it includes three standards

throughout the world, SDH/SONET uses

one common standard that applies tonetworks worldwide.


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SDH

International Telecommunication Union

(ITU) documented in standard G.707 and its

extension G.708

Uses single master clock for

synchronization.

Basic transmission rate is 155.52Mbps


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SDH/SONET

SONET is the American National Standards

Institute (ANSI) standard, which is part of

SDH, and it is used in North America.SDH/SONET was created to be an industry

standard for high-speed transmission over

optical fiber.It was actually part of a much bigger

standard in the works at that time

Broadband ISDN.


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Broadband ISDN

Two technologies were required in order to

support such applications: a transport

infrastructure (SDH/SONET) that had thesignificant bandwidth needed to support the

applications and a switching technology

(ATM)


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SDH/SONET RING

ARCHITECTURE


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Ring Example

F

CB

D

E

A

SONET: Bi-Directional Line-Switched Ring (BLSR)

SDH: Multiplex Section Shared Protection Ring (MS-SPRING)

S

S

S

S

S

S

S: Service

P

P

P

P

P

P

P: Protection

Original Circuit

Protection Switch


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Ring Example

F

CB

D

E

A

S

S

S

S

S

S

S: Service

P

P

P

P

P

P

P: Protection

Original Circuit

Protection Switch

X


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SONET/SDH Dual Rings

SONET/SDH Ring

SONET/SDH Ring

Telephone

Switch

Telephone

Switch

Telephone

Switch

Telephone

Switch

Rings can be

Wrapped if aTrunk line

is Broken


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SDH/SONET Frame

In the case of SONET, this frame is called the

Synchronous Transport Signal (STS).

In SDH, the frame is called the Synchronous

Transport Module (STM).

The electrical side of the SONET signal is

known as the STS, and the electrical side of the

SDH is known as the STM.

The optical side of a SONET/SDH signal is

known as the Optical Carrier (OC).


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SDH/SONET Hierarchy

The SDH/SONET signal hierarchy deals with

Optical Carrier (OC) levels, which refer to

the optical aspect of the transmission theoptical pulse as it travels through the fibers.

These optical pulses go through electronic

muxes, and when the signal is going throughthese network elements, the bits are packaged

in a frame for transport across the fiber.


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The SDH/SONET Hierarchy

SONET Electr ical

Signal

Optical Signal B it Rate (Mbps) SDH

Electr ical Signal

STS-1 OC-1 51.84 N/A or STM-0

STS-3 OC-3 155.52 STM-1

STS-9 OC-9 466.56 STM-3

STS-12 OC-12 622.08 STM-4

STS-18 OC-18 933.12 STM-6

STS-24 OC-24 1244.16 STM-8

STS-36 OC-36 1866.24 STM-12STS-48 OC-48 2488.32 STM-16

STS-192 OC-192 9953.28 STM-64

STS: Synchronous

Transport Signal

OC: Optical Channel STM: Synchronous

Transfer Module


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Find the data rate of an STS-1 signal

Each Synchronous Transfer Signal STS-n is

composed of 8000 frames. Each frame is a

two-dimensional matrix of bytes with 9 rowsby 90 n columns.


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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


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SONET Framing


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STM-N FRAME STRUCTURE270 x N

Columns

261 x N

Columns9 x N Columns

9Rows

= 8

bits/byte


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SDH Rate

ITU-T defines the frequency to be 8000 frames per

second for all levels in STM hierarchy

STM-1 Rate :

9 rows x 270 columns x 8 bits/byte x 8000 frames

per second

= 155.52 Mb/s

STM-4 Rate :

9 rows x (270 x 4) columns x 8 bits/byte x 8000 frames

per second

= 622 Mb/s


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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


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Duration of an STS frame

What is the duration of an STS-1 frame? STS-3 frame?

STS-n frame?

SolutionIn 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, or125 s.

What is the user data rate of an STS-1 frame (without

considering the overheads)?


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A SONET System

STS Mux/Demux beginning & end points

Regenerator repeater that regenerates the optical signals

Add/drop mux

add signals into a given path or remove a desired signalfrom a path


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An Example of a SONET Network

Section optical link connecting 2 neighbor devices

Line portion of a network between 2 muxes

Path - end to end portion of the network between 2 STS muxes


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SONET/SDH Reference Model

Path Layer (close to OSI layer 3 Network)

Line Layer (close to OSI layer 2 Data Link)

Section Layer (close to OSI layer 2 Data Link)

Photonic Layer (close to OSI layer 1 Physical)


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Manages end-to-end connection, Monitoring and

management of user connection.

-Also responsible for the movement of signalfrom its optical source to its optical destination

-Transformation of signals

-STS mux provides path layer functions

Path Layer


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Multiplexing of several path-layer connection

among nodes, Protection and Fault

Management.- STS mux and add/drop mux provide line

layer functions

Line Layer


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-Responsible for the movement of a signal

across a physical section

-Framing, error control

Section Layer


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Defines all the transmission requirements

of signals.

-Specs for optical fiber channel, sensitivityof the receiver

Photonic Layer


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Device-Layer Relationship in SONET


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STS-1 Frame Overhead

SPE

Synchronous

Payload Envelope

- Contains user

data

Path overhead

- end-to-end

tracking

information


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Mapping

Is the procedure through which signals are packed

inside an SDH frame

PDH signal passes through the following steps

before emerging as an SDH Signal

Container (C-X)

Virtual Container (VC-X)

Tributary Unit (TU-X)

Tributary Unit Group (TUG-X)

Administrative Unit (AU-4)

STM Signal


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How 2 Mb signals are mapped into an SDH stream?

C-12

VC-12

2 Mb/Sec

Container

Virtual Container

Path Overhead (POH)


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How 2 Mb signals are mapped into an SDH stream?

VC-12

STM-1/4/16

Payload

Pointer

SOHSOH

270

9

TU

(Tributary Unit)


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Formation of Synchronous Signal

Pointer

Phase relation betweenvirtual container (payload)and subordinate frame

Plesiochronous signal

Path overhead

Additional information forend-to-end monitoring

Tributary

unit (TU)

Virtual

container

(VC)

Container

(C)

Synchronous Signal


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MAPPING OF PDH SIGNAL INTO

SDH SIGNAL


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SDH Elements


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SDH Multiplexing


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PDH attributes scheme carry into different

containers. Note that first digit of lowest level

container is 1 and the second digit indicates

whether it contains 1.5 Mbps (C11) or 2Mbps

(C12).

The container and its path overhead collectively

form virtual container VC. The VC and its pointerare known as Tributary Unit (TU) if VC carries a

lower order tributaries. The largest VC in an STM-

1 frame is known as Administrative Unit (AU).


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SDH Network Elements

Path Ter minating E lement

These are the end point devices where the lower

speed channels enter and leave the SDH Network.These are known as Path Leveldevices.

Digital Cross Connect

These devices can x-connect at the STM leveldown to individual E1 streams. So an E1 stream

on one STM trunk could be x-connected to

another STM trunk.


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Regenerator

Is a device that regenerates the signal.

Add/Dr op M ul tiplexer

The Add/Drop mux has the ability to breakout

and insert low speed channels into an STM

stream.


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Sdh and Sonet