PROFITABLE CONNECTION ASSIGNMENT IN ALL OPTICAL WDM NETWORKS

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PROFITABLE CONNECTION ASSIGNMENT IN ALL OPTICAL
WDM NETWORKS

• VISHAL ANAND
• LANDER
• (Lab. for Advanced Network Design, Evaluation and
  Research)
• In collaboration with
• Tushar Katarki and Chunming Qiao
• CSE Dept., SUNY at Buffalo

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Outline

• Introduction
• Related work
• Maximum Profitability Problem
• Concluding remarks
• Questions and discussion
• Vishal Anand

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Introduction

• Optical WDM networks - future backbone for wide
  area networks.
• Physical Topology - Optical wavelength routers
  connected by fiber links.
• Lightpath or connection - Path between two end
  nodes and a wavelength on that path.
• No wavelength conversion - Any lightpath uses the
  same wavelength on all the links its path spans.
  
• Vishal Anand

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The RWA(Routing Wavelength Assignment) Problem

• Given
• a network topology
• a set of traffic demands (or connection
  requests).
• Determine the routes and wavelengths to use so as
  to satisfy the demands.
• The RWA problem is usually solved to optimize
  some specified objective(s).
• Vishal Anand

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Previous and related work

• Example objectives
• Minimize network-wide packet delay (e.g. number
  of hops).
• Maximize throughput (e.g. number of lightpaths).
• Maximize allowable capacity upgrade or
  scalability (for future traffic demands).
• Minimizing cost (network resources used) can also
  be an important objective.
• For a bandwidth broker (or carrier) maximizing
  profits is most important.
• Vishal Anand

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The Maximum Profitability Problem

• Given
• a set of connection requests, N.
• a network topology.
• earnings (revenue) Ei associated with each
  connection request, i.
• cost of using any wavelength on a link l, Cl.
• Solve the RWA problem to maximize the profit, P
  Total Earnings - Total Costs.
• Vishal Anand

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• Maximizing profit problem is a more general
  formulation.
• If EiE, for each connection/lightpath i (i.e.,
  all connections have equal earnings) OR if nN
  (i.e., all the connection requests have to be
  satisfied) then the problem is same as the
  minimizing cost problem.
• If EiE and if all connections/lightpaths have
  equal costs. Then the problem is the same as
  maximizing throughput problem.
• Hence a more direct study of the maximizing
  profit problem is necessary.
• Vishal Anand

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Network Model

• Network topology considered 16 node NSFNET.
• Cost of using each wavelength on a link , is the
  same, but varies from link to link.
• No wavelength conversion capabilities at any of
  the nodes.
• Number of wavelengths on each link in the network
  is the same.
• Vishal Anand

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Heuristic based approach

• The RWA problem is known to be NP Hard and hence
  computationally intractable.
• Maximizing profit heuristic MaxPro
• Find a cheapest path for each connection request
  and compute the profit.
• Sort the requests in the order of decreasing
  profit and store in a list.
• Satisfy connection requests in decreasing order
  of profit (a greedy approach).
• If a connection request is satisfied.
• delete that connection from the sorted list.
• Vishal Anand

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• If the cheapest path for a connection request is
  not available.
• Re-compute a new cheapest path for only that
  connection request.
• Compute the new profit for this connection
  request.
• Insert this connection into the sorted list
  depending on the profit.
• Repeat till no other connection request can be
  satisfied.

Vishal Anand
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Results and Comparison

• 1) Results obtained from MaxPro compared
  with
• a minimizing cost heuristic
• a random assignment heuristic
• 2) Results of Maxpro compared with the optimal
  results from integer linear program.

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Comparison of the heuristics

• MaxPro performs the best.
• Better than a minimizing cost heuristic.

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Integer Linear Model

• Definitions
• W Number of wavelengths on each link.
• n, L Number of nodes, links in the network.
• Earnings obtained by satisfying a
  connection request between nodes ? and ?.
• Total number of alternate routes/paths
  available to reach node ? from node ?.
• Cost of reaching node ? from node ? on
  route r.
• 1, if link j is used by the route r
  between nodes ? and ?, 0 otherwise.
• Number of connection requests between
  nodes ? and ?.
• 1, indicates that the connection
  between node ? and ? is routed on route r using
  wavelength k.

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• Objective function
• Subject to
• The total number of lightpaths established
  between a node pair should not exceed the number
  of requests between that node pair.

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• And
• The total number of lightpaths established on any
  link should not exceed the number of wavelength
  on that link.
• A wavelength on a link can support at most one
  lightpath.
• The Integrality constraint.

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Comparison of Maxpro with ILP

• MaxPro obtains on the average 90 of the results
  got from the ILP(optimal profit).

Vishal Anand
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Summary and Future work

• Formulated a RWA problem with the objective of
  maximizing the profit.
• Proposed a maximizing profit heuristic.
• Compared results of a profit maximizing heuristic
  with a minimizing cost heuristic and ILP.
• Future work
• Study the maximizing profit problem for the
  On-line traffic model.
• Extend to cases where protection and restoration
  is required for the traffic.
• Vishal Anand