SEMINAR ON Optical Burst Switching

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SEMINAR ONOptical Burst Switching

• Presented By
• Kadlag Priti
• 
  Under guidance of
• 
  Prof G.D.Puri
  
• 
  

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OVERVIEW

• Optical Switching Techniques
• Problems and solution for OCS and OPS
• What is OBS
• Why OBS? A Comparison
• OBS Fundamental
• OBS Network Edge
• Actual Data Transmission In OBS
• One-way vs. two-way reservation
• One way reservation
• Packet and OBS switching mechanism
• Just Enough Time
• Advantages And Disadvantages
• Applications
• Conclusion

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Optical Switching Techniques

• Optical Circuit Switching
• Bandwidth inefficient for bursty data (internet
  traffic).
• Frequent long circuit setup
• Waste bandwidth during off/low-traffic periods
• Optical Packet Switch
• A packet contains a header and the
  payload(variable or fixed length).
• Each node needs to buffer, process the header,
  and send it to the next switch.

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Problems and solution for OCS and OPS

• Problems
• Explosive traffic growth and bursty Traffic
  pattern
• Lack of optical buffer (RAM) for packet
  switching.
• Fiber delay lines (FDLs) are bulky and provide
  only limited delays
• Need fast processing of header and payload
• Solution
• Find a method between circuit switching and
  packet switching.
• To increase the Bandwidth efficiency.
• Thats Optical Burst Switching comes into the
  picture

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What Is OBS ...

• OBS combines benefits of OCS and OPS.
• OBS is an attempt at a new synthesis of optical
  and electronic technologies.
• OBS lies between OPS and WRN.
• In OBS, data is transmitted in variable size
  packets called Burst.
• A burst is switched to next node before its last
  bit arrives which will reduce offset time.
• No store and forward is required.
• It provides strong separation between control and
  data plane.
• It will reduce the problem of bursty traffic.

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Why OBS? A Comparison
OBS combines the best of circuit-switching and
packet-switching
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OBS Fundamentals

• In an OBS network, various types of client
  data are aggregated at the
• ingress (an edge node) and transmitted as
  data bursts which later will be
• disassembled at the egress node.
• The process of burst assembly is called as the
  burstification.

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OBS Network Edge

• Network Edge OBS users perform the following four
  functions
• Burst assembly
• Signaling
• Routing wavelength assignment
• Computation of offset time for control packet

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Data Transmission In OBS

• Data is transported in variable sized units
  called bursts.
• When a burst is ready, reservation request is
  sent to the next resource.
• Data is sent shortly after the reservation
  request, without receiving an acknowledgement of
  successful reservation.
• Control and data signals are send on different
  channels.
• There are two protocols for data transmission in
  OBS namely JET and JIT.

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One-way vs. two-way reservation

• In one-way reservation, burst is sent out after
  prespecified delay, called offset, without
  waiting for acknowledgment (ACK) that connection
  has been established.
• In conventional two-way reservation, source OBS
  user would wait for ACK before sending any data.
• Benefit of one-way reservation
• Significantly decreases connection set-up time to
  one-way end-to-end propagation delay plus time
  required to process control packet configure
  optical switch fabric at intermediate OBS nodes.
• Shortcoming of one-way reservation
• Burst can be lost since control packets may not
  be successful in setting up connections due to
  congestion on data wavelength channels.
• Retransmission of lost bursts is complex.

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ONE WAY RESERVATION
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Packet (a) and OBS(b) switching
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Just-Enough-Time (JET)

• JET is a special protocol for reservation of
  resources for burst.
• Basic ideas
• Each control packet carries the information like
  offset time and burst length.
• The offset time is chosen so that no optical
  buffering or delay is required at the
  intermediate nodes.
• Delayed reservation the reservation starts at
  the expected arrival time of the burst

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Just In Time (JIT)

• Connection establishment.
• Connection tear down.
• Connection failure due to request rejection.
• Connection failure due to data lost.

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Advantages And Disadvantages

• Advantages
• More efficient bandwidth utilization.
• Remove throughput limitation.
• Guard band between burst and header.
• Reduce processing requirements.
• Energy consumption.  
• Disadvantages
• Limited/No QoS.
• Less processing speed.
• Noise Problem

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Applications

• OBS supports multiservice traffic offering
  high
• bandwidth efficiency and low latency.
• File transfers.
• Multimedia Application like restore films,
  
• add videos, edit video clips etc.

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Conclusion

• Optical packet and circuit switching were
  discussed and compared to the new OBS switching
  technique.
• OBS is a very promising switching technique that
  will most likely be adopted in the future.
• Optical burst switching (OBS) as an efficient way
  to resolve the problem of congestion that the
  Internet is suffering from.

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Thank You
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Any Questions ?