1. SEMINAR ON Optical Burst Switching
Presented By
Kadlag Priti
Under guidance of
Prof G.D.Puri
9/20/2018

2. OVERVIEW 9/20/2018 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
9/20/2018

3. 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.
9/20/2018

4. Problems and solution for OCS and OPS…
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.
That’s Optical Burst Switching comes into the picture
9/20/2018

5. 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.
9/20/2018

6. Why OBS? A Comparison …
OBS combines the best of circuit-switching and packet-switching
9/20/2018

7. 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.
9/20/2018

8. 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
9/20/2018

9. 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.
9/20/2018

10. 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.
9/20/2018

11. ONE WAY RESERVATION
9/20/2018

12. Packet (a) and OBS(b) switching …
9/20/2018

13. 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
9/20/2018

14. Just In Time (JIT)… Connection establishment. Connection tear down.
Connection failure due to request rejection.
Connection failure due to data lost.
9/20/2018

15. Advantages And Disadvantages…
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
9/20/2018

16. 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.
9/20/2018

17. 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.
9/20/2018

18. Thank You
9/20/2018

19. Any Questions ?
9/20/2018