1. Optical Switching Switch Fabrics, Techniques and Architectures
Submitted by,
A.PRAVEEN SHARMA

2. Outline Introduction Optical Switch Optical Packet Switch
Optical Burst Switch
GMPLS
Conclusion

3. Introduction New services like VOD, IPTV
DWDM (Dense Wavelength Division Multiplexing) is developed
Then, What is problem?
Slow O/E/O conversion.
Electronic equipment is dependent on the data rate & protocol. (non-transparent)

4. Optical switch - OXC What is Optical Cross-Connect (OXC)?
Fabric
What is Optical Cross-Connect (OXC)?
Set up light paths
Electrical XC, All-optical XC, Opaque XC
Electrical XC
All-optical XC
Process
O/E/O (slow)
O/O/O (fast)
Data rate & format
Transparent? No
Yes
Implementation
Easy
Hard
Major difficulties of All-optical XC
The lack of processing at bit level in optical domain
The lack of efficient buffering in optical domain

5. Optical switch - Optical Switch Fabrics
Allow switching directly in the optical domain (All-optical)
Important parameters
Switching time (↓)
Insertion loss (↓ and loss uniformity at all input-output connections)
Crosstalk (↓)
Extinction ratio (ratio of ON-OFF power) (↑)
Polarization-dependent loss (↓)

6. Optical switch - Optical Switch Fabrics
Main optical switching technologies
Opto-mechanical Switch
Use prisms, mirrors, directional couplers.
Lack of scalability
Micro-electro-mechanical System Device (MEMS)
Use tiny reflective surfaces to redirect the light
2D-MEMS(on-off mirror)
3D-MEMS(movable mirror)
Scalability
low loss
short switching time
Low power consumption
Low crosstalk
SNU INC lab.

7. Optical switch - Optical Switch Fabrics
Electro-optic Switch
Use a directional coupler
Its coupling ratio is changed by varying the refractive index
-The Three Types of Electro Optic switches,
1.Thermo-Optic Switch
2.Liquid crystal switch
3.Bubble switch

8. Optical switch - Optical Switch Fabrics
Optomechanical Switch
MEMS
Electro-optic
Switching time
Milliseconds
Nanoseconds
Insertion loss
Low
High
PDL
high
Scalability
Bad
Good

9. Optical Packet Switching
Optical Circuit Switching
Limited circuit
Low efficiency (due to fixed bandwidth)
Optical Packet Switching
Using Packet ( = Header (for routing) + Data )
If Optical Packet Switching is realized, it can
allocate WDM channels on demand (microsecond)
share network resource efficiently
offer high-speed data rate/format transparency & configurability .

10. Optical Packet Switching
What is the problem in implementing OPS?
Long Switching time
Buffer is needed
Long switching time is due to
Buffer at Optical domain is needed .

11. Optical Packet Switching
Contention Resolution
Buffering
Using FDL (Fiber Delay Line)
bulky, expensive
Deflection routing
Only one packet – desired link, others – longer links
There can be the looping of packets .

12. Optical Packet Switching
Architecture
Output
Input
O/E interface: extract the header info.
FDL
SNU INC lab.

13. Optical Packet Switching
Shared Wavelength Converters
Reduce Tunable Wavelength converter
SNU INC lab.

14. Optical Burst Switching
Switch the channels entirely in the optical domain using electronic tech.
Process
Assemble the packets
Switched through transparently without any conversion
Convert into the original packets .

15. The future of Optical switching.

16. GMPLS - Generalized Multiprotocol Label Switching
Extends common control plane to support various interfaces.
GMPLS can support
Packet switching
Time-division (MPλS (wavelength switching) -Spatial-switching (OXC) .

17. Conclusion Switching functions must be executed optically
Two obstacles
In the future, breakthroughs may counteract the fundamental limitations of optics
Then, current network is completely changed .

18. THANK YOU .