y(j)s sonet slide 1 sonet. y(j)s sonet slide 2 the pstn circa 1900 pair of copper wires “local...

Y(J)S SONET Slide 1

SONETSONET

Y(J)S SONET Slide 2

The PSTN circa 1900The PSTN circa 1900

pair of copper wires

“local loop”

manual routing at local exchange office (CO)

• Analog voltage travels over copper wire end-to-end • Voice signal arrives at destination severely attenuated and distorted

• Routing performed manually at exchanges office(s)• Routing is expensive and lengthy operation• Route is maintained for duration of call

Y(J)S SONET Slide 3

The Digitalization of the PSTNThe Digitalization of the PSTN

Shannon (Bell Labs) proved that

Digital communicationsis always better than

Analog communicationsand the PSTN became digital

Better means More efficient use of resources (e.g. more channels on trunks) Higher voice quality (less noise, less distortion) Added features

After the invention of the transistor, in 1963 T-carrier system (TDM)

1 byte per sample – 8000 samples per second

t

timeslots

Y(J)S SONET Slide 4

OAMOAMAnalog channels and 64 kbps digital channels

do not have mechanisms to check signal validity and quality

thus major faults could go undetected for long periods of time hard to characterize and localize faults when reported minor defects might be unnoticed indefinitely

Solution is to add mechanisms based on overhead

as Packet networks evolved, more and more overhead was dedicated

toOperations, Administration and Maintenance (OAM) functions

including: monitoring for valid signal defect reporting alarm indication/inhibition (AIS)

Y(J)S SONET Slide 5

SONET/SDH SONET/SDH

motivation and historymotivation and history

Y(J)S SONET Slide 6

First stepFirst step SONET was developed by ANSI;

SDH TSDH was developed by ITU-T.

Synchronous Optical NETwork

Designed for optical transport (high bitrate)

Direct mapping of lower levels into higher ones

Carry all Packet types in one universal hierarchy– ITU version = Synchronous Digital Hierarchy– different terminology but interoperable

Overhead doesn’t increase with rate

OAM designed-in from beginning

Y(J)S SONET Slide 7

LayersLayers

SONET defines four layers:

1.Path

2.Line

3.Section and

4.Photonic

Y(J)S SONET Slide 8

SONET architectureSONET architecture

SONET (SDH) has at 3 layers: path – end-to-end data connection, muxes tributary signals path section

– there are STS paths + Virtual Tributary (VT) paths

line – protected multiplexed SONET payload multiplex section section – physical link between adjacent elements regenerator section

Each layer has its own overhead to support needed functionality

SDH terminology

Path

Termination

Path

Termination

Line

Termination

Line

Termination

Section

Termination

path

line line line

ADM ADMregenerator

section section sectionsection

SONET System consists of Signal, devices and connections.

Device–layer relationship in Device–layer relationship in SONETSONET

Y(J)S SONET Slide 9

Y(J)S SONET Slide 10

rates rates

and and

frame structureframe structure


SONET STS-1 frameSONET STS-1 frame

Each STS-1 frame is 90 columns * 9 rows = 810 bytes

There are 8000 STS-1 frames per secondso each byte represents 64 kbps (each column is 576 kbps)

Thus the basic STS-1 rate is 51.840 Mbps


SDH STM-1 frameSDH STM-1 frame

Synchronous Transport Modules are the bit-signals for SDH

Each STM-1 frame is 270 columns * 9 rows = 2430 bytes

There are 8000 STM-1 frames per second

Thus the basic STM-1 rate is 155.520 Mbps

3 times the STS-1 rate!


SONET/SDH ratesSONET/SDH rates

STS-N has 90N columns STM-M corresponds to STS-N with N = 3M

SDH rates increase by factors of 4 each time

STS/STM signals can carry PDH tributaries, for example:

STS-1 can carry 1 T3 or 28 T1s or 1 E3 or 21 E1s

STM-1 can carry 3 E3s or 63 E1s or 3 T3s or 84 T1s

SONET SDH columns rate

STS-1 90 51.84M

STS-3 STM-1 270 155.52M

STS-12 STM-4 1080 622.080M

STS-48 STM-16 4320 2488.32M

STS-192 STM-64 17280 9953.28M


STS-1 frame structureSTS-1 frame structure

TransportOverhead

TOH

THANK YOU.


y(j)s sonet slide 1 sonet. y(j)s sonet slide 2 the pstn circa 1900 pair of copper wires “local...

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