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Routing, wavelength assignment and pricing in optical (multi domain) networks

Friday, 2 March, 2012 - 18:00
Campus: Brussels Humanities, Sciences & Engineering campus
Faculty: Science and Bio-engineering Sciences
Pasquale Gurzi
phd defence

Given the huge amount of bandwidth offered by the optical transmission
medium, it is widely believed that IP over optical networks will be a major
component of the next generation Internet.

In this dissertation, we address some important routing and resource al-
location problems stated at different network layers. Starting from the
optical layer, we first consider the dynamic routing and wavelength assign-
ment problem in transparent optical networks. We argue that shortest path
based routing techniques are not always suited for automatically switched
optical networks, which require dynamic lightpath establishment for every
new connection request. Especially in wide area networks, where physical
impairments must be taken into account, there is the need of optimizing
the lightpath set up process to improve the quality of transmission other
than resource utilization and blocking probability of the network. Here,
we show how significant improvements can be achieved by jointly consider-
ing the routing and wavelength assignment problem. Moreover, traditional
shortest path search has been replaced with our algorithm based on a flow
network representation. Two routing algorithms, based on a maximum flow
and on a minimum cost flow computation, have been proposed to improve
overall performance with a relatively low increase in complexity.

When considering the integrated IP over optical networks routing problem,
we deal with the multilayer traffic engineering paradigm where lightpath
establishment is a service provided from the optical to the IP layer. Due
to the convergence of most services on the IP layer, optical networks need
to provide transport for a variety of applications having different Quality
of Service (QoS) requirements. This implies that the Differentiated Service
(DiffServ) paradigm, which considers the QoS in pure IP networks, needs
to be extended to the new underlying infrastructure. Here we argue that
service differentiation can be achieved by using a different routing policy for
each Class of Service (CoS) in combination with a virtual topology differ-
entiation mechanism. We propose and compare three service differentiation
schemes and show that the best performance is achieved when the different
CoS share a limited amount of resources.

To fully address the routing problem in IP over optical networks we also
take into account the economic aspect arising in multi-domain routing oper-
ations which, after all, supports the growth of the telecommunication sector.
Internet Service Providers (ISPs) have interest in offering efficient transport
services resulting in a positive impact on their monetary return. When ISPs
charge customers or other ISPs for using their transit link they can set the
price in order to maximize their expected utility taking into account the load
in the network and other ISPs’ possible choices. The competition among
ISPs generates a continuous action game where the ISP’s action is the choice
of the price of its transit links. Hence, we study the inter-domain routing
problem from a game theoretic prospective and we analyze the possible out-
comes in terms of efficiency and stability of the solution. We propose two
reinforcement learning algorithms which may be used as a tool by ISPs to
learn the optimal price and equilibrium solution. We discuss the theoretical
aspects arising in the game and show the advantages of learning the links
price using reinforcement learning.

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