8 research outputs found
Dynamic wavelength allocation in IP/WDM metro access networks
Ankara : The Department of Electrical and Electronics Engineering and the Institute of Engineering and Science of Bilkent University, 2008.Thesis (Ph.D.) -- Bilkent University, 2008.Includes bibliographical references leaves 132-139.Increasing demand for bandwidth and proliferation of packet based traffic
have been causing architectural changes in the communications infrastructure.
In this evolution, metro networks face both the capacity and dynamic adaptability
constraints. The increase in the access and backbone speeds result in high
bandwidth requirements, whereas the popularity of wireless access and limited
number of customers in metro area necessitates traffic adaptability. Traditional
architecture which has been optimized for carrying circuit-switched connections,
is far from meeting these requirements. Recently, several architectures have been
proposed for future metro access networks. Nearly all of these solutions support
dynamic allocation of bandwidth to follow fluctuations in the traffic demand.
However, reconfiguration policies that can be used in this process have not been
fully explored yet. In this thesis, dynamic wavelength allocation (DWA) policies
for IP/WDM metro access networks with reconfiguration delays are considered.
Reconfiguration actions incur a cost since a portion of the capacity becomes idle
in the reconfiguration period due to the signalling latencies and tuning times of
optical transceivers. Exact formulation of the DWA problem is developed as a
Markov Decision Process (MDP) and a new cost function is proposed to attain
both throughput efficiency and fairness. For larger problems, a heuristic approach
based on first passage probabilities is developed. The performance of the method
is evaluated under both stationary and non-stationary traffic conditions. The
effects of relevant network and traffic parameters, such as delay and flow size are
also discussed. Finally, performance bounds for the DWA methods are derived.Yetginer, EmrePh.D
Traffic engineering and regenerator placement in MPLS and GMPLS networks with restoration
Ankara : The Department of Electrical and Electronics Engineering and Sciences of Bilkent University, 2002.Thesis (Master's) -- Bilkent University, 2002.Includes bibliographical references leaves 78-81.Yetginer, EmreM.S
Robust path design algorithms for traffic engineering with restoration in MPLS networks
In this paper we study traffic engineering in Multiprotocol Label Switching (MPLS) networks. We consider off-line computation of disjoint working and restoration paths where path rerouting is used as the restoration scheme. We first compute maximum number of paths for each demand such that paths satisfy diversity requirements. Using the generated path set we study four different approaches for selecting working and restoration paths, and formulate each method as an Integer Linear Programming (ILP) problem. The first two methods treat working and restoration path design problems separately. We propose two new path design methods that jointly optimize the working and restoration paths. A traffic uncertainty model is developed in order to evaluate performances of these four approaches based on their robustness with respect to changing traffic patterns. We compare these design approaches based on the number of additional demands carried and the distribution of residual capacity over the network. It is shown through simulations that the weighted load balancing method proposed in this paper outperforms the other three methods in handling traffic demand uncertainty
"title"Traffic engineering and regenerator placement in GMPLS networks with restoration"/title"
In this paper we study regenerator placement and traffic engineering of restorable paths in Generalized Multipro-tocol Label Switching (GMPLS) networks. Regenerators are necessary in optical networks due to transmission impairments. We study a network architecture where there are regenerators at selected nodes and we propose two heuristic algorithms for the regenerator placement problem. Performances of these algorithms in terms of required number of regenerators and computational complexity are evaluated. In this network architecture with sparse regeneration, offline computation of working and restoration paths is studied with bandwidth reservation and path rerouting as the restoration scheme. We study two approaches for selecting working and restoration paths from a set of candidate paths and formulate each method as an Integer Linear Programming (ILP) prob-lem. Traffic uncertainty model is developed in order to compare these methods based on their robustness with respect to changing traffic patterns. Traffic engineering methods are compared based on number of additional demands due to traffic uncertainty that can be carried. Regenerator placement algorithms are also evaluated from a traffic engineering point of view.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only