Translucent optical networks the way forward

Types of Optical NetworksRegenerationComparisons

Network PlanningTypes of Translucent Networks

Other TopicsConclusions

ExercisesAppendix

Translucent Optical Networks:The Way Forward

Philippe P. S. Fanaro

October 2014

Philippe P. S. Fanaro Translucent Optical Networks: The Way Forward 1 / 21




ExercisesAppendix

Opaque

All Electronic Switching

TranslucentBalance between Electronic and Optical Switching

Transparent

All Optical Switching

EvolutionOpaque → Transparent





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3RReamplify + Reshape + Retime

2RReamplify + Reshape

Regeneration

Could be accomplished purely in the optical domain, but it is morereliably done through the electronic format.





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Today

Transparent � TRANSLUCENT ≈ Transparent

Translucent Advantages

→ OXCs available to all wavelengths ⇒ sharing improves regeneratorusage.→ Wavelength conversion capability of regenerators alleviates wavelengthcollisions, which saves the need for wavelength converters.→ Unlikelihood of OXC nodes being fully opticalin the near future (thearticle was written in 2007 though.)





ExercisesAppendix

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 bythe GMPLS.⇒ We will focus on the first 3 criteria.





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Transparent IslandsSparsely Opaque NodesOXC Nodes

Types

→ Transparent Islands→ Sparsely Placed Opaque Nodes→ Translucent Nodes





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Transparent Islands

→ Opaque: with regeneration (not necessarily conversion)→ Transparent: no regeneration





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Main CriteriaWe 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).





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One Simple Strategy

Nodes which have more lightpaths passing through them receive a higherweight, so a traffic balance may be achieved and all nodes be reachablefrom one another.





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Solving the Problem

→ Again an NP-complete K-Cluster problem...→ Solveable through a 2D-Dijkstra algorithm, i.e., a Dijkstra algorithmwhich has 2 variables to minimize: wavelength losses and topologicaldistance.





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Main Features→ Most Uniform Signal Regeneration Distribution.→ Allocation could be solved in a similar fashion as the 2D- Dijkstrafrom the Sparsely Opaque Nodes Placement.





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Solving the Problem

→ Apply different weights to the nodes of the network proportional tothe ongoing traffic through them.→ Then minimize the number of regenerators on each node.





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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 thealternative way, it would be a K-center problem.→ Again a 2D-Dijkstra algorithm is adequate.





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Other Topics for Research

→ Protection and restoration of translucent networks.→ Traffic grooming on sparsely placed opaque nodes or translucentnodes.→ Network performance monitoring and fault detection on sparselyplaced opaque nodes.→ Multicasting on sparsely placed opaque nodes.





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Suggestion

→ Due to the fine granularity of the IP layer, the author suggests acombination of the IP and the Optical layers in order to achieve a bettermulticasting.→ The optical layer would be responsible for a coarse trimming, whilethe IP layer, a more refined one.





ExercisesAppendix

From the Author→ Further Research is necessary.→ Obviously, opaque networks are the way forward, a natural transitioninto fully transparent networks. As argued, they offer a more efficientallocation of resources.





ExercisesAppendix

Exercises1 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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Reference(s)Answers to the Exercises

This Presentation’s Main Paper:

G. Shen and R. S. Tucker, Translucent optical networks: The wayforward, 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.


http://www.gangxiang-shen.com/publication/shen_tucker.pdf

http://www.gangxiang-shen.com/publication/shen_tucker.pdf

http://www-m3.ma.tum.de/foswiki/pub/MN0506/WebHome/dijkstra.pdf

http://www-m3.ma.tum.de/foswiki/pub/MN0506/WebHome/dijkstra.pdf




ExercisesAppendix


(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 electronicdomain.

2 The second one is a transition into the third. The translucentoptical network tries to accomplish only the necessary optical toelectronic conversion and/or regeneration in order to minimize thecosts and maximize the speed of the flux in the network.

3 The third and most probable future of the optical networks is thetransparent optical network. Here, the network has noopto-electronic conversion, i.e., the network is fully optical, thus thespeed of the ongoing flux is maximized.





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(2): Why are Translucent Optical Networks the Way Forward?

Translucent Optical Networks are a mean of optimization of the morecommon Opaque Optical Network in which, through clever Opaque Nodeor OXC Regenerators placement, one tries to minimize the costs andmaximize the speed of the traffic flux.





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(3): Which of the 3 types of Translucent Networks is the best?

The OXC Nodes Network is the most optimal since there will be anadequate number of regenerators at each node. But it might beextremely complicated to solve in complex networks. So in some casesthe Transparent Island or Sparsely Opaque Nodes Placement might be aneasier and simpler solution.


Engineering

Translucent optical networks the way forward