3..optical packet switching network

8/7/2019 3..Optical Packet Switching Network

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OPTICAL PACKET SWITCHING

NETWORK



WHAT IS A SWITCH ??

y Device that channels incoming data from any of the

multiple input ports to any of the output ports.y SWITCHING TYPES:

1..CIRCUIT SWITCHING

2..PACKET SWITCHING

y

In circuit switching a dedicated path is established fory communication. EX..telephone networks

y In packet switching, the messages to be transmitted isbroken to small PACKETS.



Todays switching networks:

y ROUTING and TRANSMISSION are the two functionsrequired to move packets through networks

y The router uses the information in the packet-(IPheader, Type, Priority) to route the packets from inputto output with minimal packet loss..



Optic fibers

y A medium for transmitting information in the form of light pulses along a glass/fiber

y Also known as LIGHT PIPEy Provides greater bandwidth



WAVE LENGTH DIVISION MULTIPLEXING (WDM)

A technology used to increase the information rate

Here multiple signals can traverse through a singlestrand of optic fiber



USE:B y the use of thistechnology, optic

fibertransmissionsystem can carry 32-80 wavelengths

modulated @2.5gbps-10gbpsper wavelength



OPTICAL TRANSMISSION MEDIA

In MAN, links between the nodes are optical fibersHere packets are in the optical formatO-E-O conversion are required at the interface



LIMITATIONS

LIMITED PACKET PROCESSINGSLOW OPERATIONCOST AND COMPLEXITY CROSS TALK

These limitations degrades the performance of the

system affecting the bandwidth



SOLUTION!

The solution is OPTICAL PACKET SWITCHING

The signals are being processed by means of OPTICAL

SWITCH FA BRIC

Optical signalsOptical signals

OPTICAL SWITCH FA BRIC



SWITCH

ARCHITECTURE

An OPS node consists of

following components

1. INPUT INTERFACE

2. SWITCHINGMATRIX 3. BUFFER 4. OUTPUT INTERFACE

5. ELECTRONICCONTROL

UNIT



1.INPUT INTERFACE

Wave length conversion

->conversion of external to internal

y wavelengths->identification of the beginning and end of the

header and payloadProvides synchronization

Header processing



CONTROL UNIT

Processing routing informationUpdates header informationForwards header to output interface



SWITCHING MATRIX

Optical switching of the payloads according tothe commands from the control unit



OUTPUT INTERFACE

Provides 3R(reamplification ,reshaping, retiming)regeneration

Attaches updated header to correspondingoptical payloadConversion of internal to external wavelengthresynchronization



GENERAL PACKET FORMAT

A generic packet format consists of

y HeaderPayload

Additional GUARD B ANDS before and after payload



PACKET HEADER

A packet header may comprise of following fields

y Sync - provides synchronization

y Source Label -provides source node addressDestination Label-provides destination nodeaddress

y Type-type and priority of the carried payload



continued

y Sequence Number :Packet sequence number toreorder packets arriving out of order and guarantee in-

order packet delivery

y OAM: Operation, Administration,Maintenance

y HEC: Head Error Correction



OPTICAL SWITCHING TECHNIQUES

Two types of optical switching techniques

1.ALL OPTICAL LA BEL SWAPPING (AOLS)

2.LIQUID CRYSTAL SWITCHES



ALL OPTICAL LABEL SWAPPING

y Consists of Optical Core Networks

1.Edge Router

2.Core Router

y Here Packets can be routed independent of PayloadBit Rate, Coding format ,length etc

y Can handle IP packets as well as ATM cells



LABEL

A Lower Bit Rate (LA BEL) is attached to the

front of the packet A LA BEL contains-

1.Error checking information2. Source Information

3. Destination Information4. Framing and timing information



PROCESS

Packets entered through EDGE nodes (source

side) is encapsulated with the optical labelHeader is removed. At internal CORE nodes, the label is optically erased,embedded with a new label

The payloads with the label gets routed in the networks

At the Edge nodes (destination side) ,the label is Erasedback to packet payload

Updated header is encapsulated to the payload



All tical la l s a i g



2.LIQUID CRYSTAL SWITCHES

Principle : -when an electric field is applied toliquid crystal, the molecules line up andbecome opaque

The molecules are so thin and straight, will allow light of aparticular orientation to pass through the liquid crystal

It consists of 2 components

4. CELL

5. DISPLACER



CELL AND DISPLACER

CELL: Formed by placing the liquid crystal between 2plates of glass

Glass is coated with oxide materials that conductselectricity

The function is to REORIENT the polarized lightentering the cell

DISPL A CER:It is a composite crystal that directs the polarized light

leaving the cell



conclusion

The new technology regarded as ULTIMATE

y SOLUTION to bandwidth needs PROVIDING

-->IMPROVED EFFICIENCY -->LOW COSTS

-->UTILISE DWDM



DONE BY

SHIKHA SINGH B. Tech(I.T.)- 3rd year

K.N.I.P.S.S., Sultanpur

3..optical packet switching network

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