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OPTICAL PACKET SWITCHING

OPTICAL PACKET SWITCHING. Done by : ARUN JOY R7A11. WHAT IS A SWITCH ??.

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OPTICAL PACKET SWITCHING

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  1. OPTICAL PACKET SWITCHING Done by : ARUN JOY R7A11

  2. WHAT IS A SWITCH ?? • Device that channels incoming data from any of the multiple input ports to any of the output ports. • SWITCHING TYPES • CIRCUIT SWITCHING • PACKET SWITCHING • In circuit switching a dedicated path is established for communication. E.g.: telephone networks • In packet switching, the messages to be transmitted is broken to small PACKETS.

  3. Today’s switching networks • ROUTING and TRANSMISSION are the two functions required to move packets through networks • The router uses the information in the packet-(IP header, Type, Priority) to route the packets from input to output with minimal packet loss

  4. Optic fibers • A medium for transmitting information in the form of light pulses along a glass/fiber • Also known as LIGHT PIPE • Provides greater bandwidth

  5. WAVE LENGTH DIVISION MULTIPLEXING (WDM) • A technology used to increase the information rate • Here multiple signals can traverse through a single strand of optic fiber

  6. USE • By the use of this technology, optic fiber transmission system can carry 32-80 wavelengths modulated @ 2.5gbps-10gbps per wavelength

  7. OPTICAL TRANSMISSION MEDIA • In MAN, links between the nodes are optical fibers • Here packets are in the optical format • O-E-O conversion are required at the interface

  8. LIMITATIONS • LIMITED PACKET PROCESSING • SLOW OPERATION • COST AND COMPLEXITY • CROSS TALK These limitations degrades the performance of the system affecting the bandwidth

  9. SOLUTION! • The solution is OPTICAL PACKET SWITCHING • The signals are being processed by means of OPTICAL SWITCH FABRIC OPTICAL SWITCH FABRIC OPTICAL SIGNALS OPTICAL SIGNALS

  10. SWITCH ARCHITECTURE • An OPS node consists of following components • INPUT INTERFACE • SWITCHING MATRIX • BUFFER • OUTPUT INTERFACE • 5. ELECTRONIC CONTROL UNIT

  11. 1.INPUT INTERFACE • Wave length conversion ->conversion of external to internal wavelengths ->identification of the beginning and end of the header and payload • Provides synchronization • Header processing

  12. CONTROL UNIT • Processing routing information • Updates header information • Forwards header to output interface

  13. SWITCHING MATRIX • Optical switching of the payloads according to the commands from the control unit

  14. OUTPUT INTERFACE • Provides 3R(reamplification,reshaping,retiming) regeneration • Attaches updated header to corresponding optical payload • Conversion of internal to external wavelength • resynchronization

  15. GENERAL PACKET FORMAT • A generic packet format consists of • Header • Payload • Additional GUARD BANDS before and after payload

  16. PACKET HEADER • A packet header may comprise of following fields • Sync-provides synchronization • Source Label-provides source node address • Destination Label-provides destination node address • Type-type and priority of the carried payload

  17. continued… • Sequence Number:Packet sequence number to reorder packets arriving out of order and guarantee in-order packet delivery • OAM: Operation, Administration, Maintenance • HEC: Head Error Correction

  18. OPTICAL SWITCHING TECHNIQUES • Two types of optical switching techniques 1.ALL OPTICAL LABEL SWAPPING (AOLS) 2.LIQUID CRYSTAL SWITCHES

  19. ALL OPTICAL LABEL SWAPPING • Consists of Optical Core Networks 1.Edge Router 2.Core Router • Here Packets can be routed independent of Payload Bit Rate, Coding format ,length etc • Can handle IP packets as well as ATM cells

  20. LABEL • A Lower Bit Rate (LABEL) is attached to the front of the packet • A LABEL contains- 1.Error checking information 2. Source Information 3. Destination Information 4. Framing and timing information

  21. PROCESS • Packets entered through EDGE nodes (source side) is encapsulated with the optical label • Header 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 Erased back to packet payload • Updated header is encapsulated to the payload

  22. All optical label swapping

  23. 2.LIQUID CRYSTAL SWITCHES • Principle : -when an electric field is applied to liquid crystal, the molecules line up and become opaque • The molecules are so thin and straight, will allow light of a particular orientation to pass through the liquid crystal • It consists of 2 components • CELL • DISPLACER

  24. CELL AND DISPLACER CELL: Formed by placing the liquid crystal between 2 plates of glass Glass is coated with oxide materials that conducts electricity The function is to REORIENT the polarized light entering the cell DISPLACER: It is a composite crystal that directs the polarized light leaving the cell

  25. conclusion • The new technology –regarded as ULTIMATE SOLUTION to bandwidth needs PROVIDING ->IMPROVED EFFICIENCY ->LOW COSTS ->UTILISE DWDM

  26. THANK YOU!!!

  27. QUESTIONS ????

  28. DONE BY • ARUN JOY • 7TH SEMESTER,DEPARTMENT OF COMPUTER SCIENCE AND ENGG, SREE NARAYANA GURUKULAM COLLAGE OF ENGINEERING,KADAYIRUPPU.

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