The document discusses different types of optical networks, including opaque, translucent, and transparent networks. It focuses on translucent networks, which aim to balance electronic and optical switching. Three types of translucent networks are described: transparent islands with sparsely placed opaque nodes for regeneration, sparsely placed opaque nodes throughout the network, and networks with translucent nodes having some regeneration capability. Algorithms like Dijkstra's are presented for solving problems related to dividing the network into transparent islands and placing regenerators in translucent networks.

1. Types of Optical Networks
Regeneration
Comparisons
Network Planning
Types of Translucent Networks
Other Topics
Conclusions
Exercises
Appendix
Translucent Optical Networks:
The Way Forward
Philippe P. S. Fanaro
October 2014
Philippe P. S. Fanaro Translucent Optical Networks: The Way Forward 1 / 21

2. Types of Optical Networks
Regeneration
Comparisons
Network Planning
Types of Translucent Networks
Other Topics
Conclusions
Exercises
Appendix
Opaque
All Electronic Switching
Translucent
Balance between Electronic and Optical Switching
Transparent
All Optical Switching
Evolution
Opaque ! Transparent
Philippe P. S. Fanaro Translucent Optical Networks: The Way Forward 2 / 21

3. Types of Optical Networks
Regeneration
Comparisons
Network Planning
Types of Translucent Networks
Other Topics
Conclusions
Exercises
Appendix
3R
Reamplify + Reshape + Retime
2R
Reamplify + Reshape
Regeneration
Could be accomplished purely in the optical domain, but it is more
reliably done through the electronic format.
Philippe P. S. Fanaro Translucent Optical Networks: The Way Forward 3 / 21

4. Types of Optical Networks
Regeneration
Comparisons
Network Planning
Types of Translucent Networks
Other Topics
Conclusions
Exercises
Appendix
Today
Transparent TRANSLUCENT Transparent
Translucent Advantages
! OXCs available to all wavelengths ) sharing improves regenerator
usage.
! Wavelength conversion capability of regenerators alleviates wavelength
collisions, which saves the need for wavelength converters.
! Unlikelihood of OXC nodes being fully opticalin the near future (the
article was written in 2007 though.)
Philippe P. S. Fanaro Translucent Optical Networks: The Way Forward 4 / 21

5. Types of Optical Networks
Regeneration
Comparisons
Network Planning
Types of Translucent Networks
Other Topics
Conclusions
Exercises
Appendix
4 Basic Criteria
! Transparent Island Division
! Opaque Node Placement
! 2R/3R Regenerator Allocation
! Routing and Wavelength Assignement
Focus
! First 3 criteria are specific to your type of translucent network.
! Last Criteria can be handle well enough in every type of network by
the GMPLS.
) We will focus on the first 3 criteria.
Philippe P. S. Fanaro Translucent Optical Networks: The Way Forward 5 / 21

6. Types of Optical Networks
Regeneration
Comparisons
Network Planning
Types of Translucent Networks
Other Topics
Conclusions
Exercises
Appendix
Transparent Islands
Sparsely Opaque Nodes
OXC Nodes
Types
! Transparent Islands
! Sparsely Placed Opaque Nodes
! Translucent Nodes
Philippe P. S. Fanaro Translucent Optical Networks: The Way Forward 6 / 21

7. Types of Optical Networks
Regeneration
Comparisons
Network Planning
Types of Translucent Networks
Other Topics
Conclusions
Exercises
Appendix
Transparent Islands
Sparsely Opaque Nodes
OXC Nodes
Transparent Islands
! Opaque: with regeneration (not necessarily conversion)
! Transparent: no regeneration
Philippe P. S. Fanaro Translucent Optical Networks: The Way Forward 7 / 21

8. Types of Optical Networks
Regeneration
Comparisons
Network Planning
Types of Translucent Networks
Other Topics
Conclusions
Exercises
Appendix
Transparent Islands
Sparsely Opaque Nodes
OXC Nodes
Main Criteria
We want to minimize the costs:
# Number of Transparent Islands )
) # Opaque Nodes )
) # Cost
How to solve the Problem: NP-complete K-cluster
! Choice of some criteria to use the L.M.S.
! The problem can be solved in polynomial time (NP- complete).
Philippe P. S. Fanaro Translucent Optical Networks: The Way Forward 8 / 21

9. Types of Optical Networks
Regeneration
Comparisons
Network Planning
Types of Translucent Networks
Other Topics
Conclusions
Exercises
Appendix
Transparent Islands
Sparsely Opaque Nodes
OXC Nodes
One Simple Strategy
Nodes which have more lightpaths passing through them receive a higher
weight, so a traffic balance may be achieved and all nodes be reachable
from one another.
Philippe P. S. Fanaro Translucent Optical Networks: The Way Forward 9 / 21

10. Types of Optical Networks
Regeneration
Comparisons
Network Planning
Types of Translucent Networks
Other Topics
Conclusions
Exercises
Appendix
Transparent Islands
Sparsely Opaque Nodes
OXC Nodes
Solving the Problem
! Again an NP-complete K-Cluster problem...
! Solveable through a 2D-Dijkstra algorithm, i.e., a Dijkstra algorithm
which has 2 variables to minimize: wavelength losses and topological
distance.
Philippe P. S. Fanaro Translucent Optical Networks: The Way Forward 10 / 21

11. Types of Optical Networks
Regeneration
Comparisons
Network Planning
Types of Translucent Networks
Other Topics
Conclusions
Exercises
Appendix
Transparent Islands
Sparsely Opaque Nodes
OXC Nodes
Main Features
! Most Uniform Signal Regeneration Distribution.
! Allocation could be solved in a similar fashion as the 2D- Dijkstra
from the Sparsely Opaque Nodes Placement.
Philippe P. S. Fanaro Translucent Optical Networks: The Way Forward 11 / 21

12. Types of Optical Networks
Regeneration
Comparisons
Network Planning
Types of Translucent Networks
Other Topics
Conclusions
Exercises
Appendix
Transparent Islands
Sparsely Opaque Nodes
OXC Nodes
Solving the Problem
! Apply different weights to the nodes of the network proportional to
the ongoing traffic through them.
! Then minimize the number of regenerators on each node.
Philippe P. S. Fanaro Translucent Optical Networks: The Way Forward 12 / 21

13. Types of Optical Networks
Regeneration
Comparisons
Network Planning
Types of Translucent Networks
Other Topics
Conclusions
Exercises
Appendix
Transparent Islands
Sparsely Opaque Nodes
OXC Nodes
An Alternative
Placing central regenerators to minimize the costs (Opaque Islands).
Solving the Problem
! Again an NP-complete K-cluster problem. If we would choose the
alternative way, it would be a K-center problem.
! Again a 2D-Dijkstra algorithm is adequate.
Philippe P. S. Fanaro Translucent Optical Networks: The Way Forward 13 / 21

14. Types of Optical Networks
Regeneration
Comparisons
Network Planning
Types of Translucent Networks
Other Topics
Conclusions
Exercises
Appendix
Other Topics for Research
! Protection and restoration of translucent networks.
! Traffic grooming on sparsely placed opaque nodes or translucent
nodes.
! Network performance monitoring and fault detection on sparsely
placed opaque nodes.
! Multicasting on sparsely placed opaque nodes.
Philippe P. S. Fanaro Translucent Optical Networks: The Way Forward 14 / 21

15. Types of Optical Networks
Regeneration
Comparisons
Network Planning
Types of Translucent Networks
Other Topics
Conclusions
Exercises
Appendix
Suggestion
! Due to the fine granularity of the IP layer, the author suggests a
combination of the IP and the Optical layers in order to achieve a better
multicasting.
! The optical layer would be responsible for a coarse trimming, while
the IP layer, a more refined one.
Philippe P. S. Fanaro Translucent Optical Networks: The Way Forward 15 / 21

16. Types of Optical Networks
Regeneration
Comparisons
Network Planning
Types of Translucent Networks
Other Topics
Conclusions
Exercises
Appendix
From the Author
! Further Research is necessary.
! Obviously, opaque networks are the way forward, a natural transition
into fully transparent networks. As argued, they offer a more efficient
allocation of resources.
Philippe P. S. Fanaro Translucent Optical Networks: The Way Forward 16 / 21

17. Types of Optical Networks
Regeneration
Comparisons
Network Planning
Types of Translucent Networks
Other Topics
Conclusions
Exercises
Appendix
Exercises
1 Differentiate the types of Optical Networks discussed.
2 Why are Translucent Optical Networks the Way Forward?
3 Which of the 3 types of Translucent Networks is the best?
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18. Types of Optical Networks
Regeneration
Comparisons
Network Planning
Types of Translucent Networks
Other Topics
Conclusions
Exercises
Appendix
Reference(s)
Answers to the Exercises
This Presentation’s Main Paper:
G. Shen and R. S. Tucker, Translucent optical networks: The way
forward, IEEE Commun. Mag., vol. 45, no. 2, pp. 48 54, Feb. 2007.
Dijkstra’s Algorithm (Original Article):
E. W. Dijkstra, A note on two problems in connection with graphs,
Numer. Math., 1:269–271, 1959.
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19. Types of Optical Networks
Regeneration
Comparisons
Network Planning
Types of Translucent Networks
Other Topics
Conclusions
Exercises
Appendix
Reference(s)
Answers to the Exercises
(1): Differentiate the types of Optical Networks.
There are mainly 3 types of optical networks:
1 The first one would be the opaque in which the regeneration and
treatment of the optical signal is accomplished in the electronic
domain.
2 The second one is a transition into the third. The translucent
optical network tries to accomplish only the necessary optical to
electronic conversion and/or regeneration in order to minimize the
costs and maximize the speed of the flux in the network.
3 The third and most probable future of the optical networks is the
transparent optical network. Here, the network has no
opto-electronic conversion, i.e., the network is fully optical, thus the
speed of the ongoing flux is maximized.
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20. Types of Optical Networks
Regeneration
Comparisons
Network Planning
Types of Translucent Networks
Other Topics
Conclusions
Exercises
Appendix
Reference(s)
Answers to the Exercises
(2): Why are Translucent Optical Networks the Way Forward?
Translucent Optical Networks are a mean of optimization of the more
common Opaque Optical Network in which, through clever Opaque Node
or OXC Regenerators placement, one tries to minimize the costs and
maximize the speed of the traffic flux.
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21. Types of Optical Networks
Regeneration
Comparisons
Network Planning
Types of Translucent Networks
Other Topics
Conclusions
Exercises
Appendix
Reference(s)
Answers to the Exercises
(3): Which of the 3 types of Translucent Networks is the best?
The OXC Nodes Network is the most optimal since there will be an
adequate number of regenerators at each node. But it might be
extremely complicated to solve in complex networks. So in some cases
the Transparent Island or Sparsely Opaque Nodes Placement might be an
easier and simpler solution.
Philippe P. S. Fanaro Translucent Optical Networks: The Way Forward 21 / 21