152 research outputs found
Optimized Design of Survivable MPLS over Optical Transport Networks. Optical Switching and Networking
In this paper we study different options for the survivability implementation
in MPLS over Optical Transport Networks in terms of network resource usage and
configuration cost. We investigate two approaches to the survivability
deployment: single layer and multilayer survivability and present various
methods for spare capacity allocation (SCA) to reroute disrupted traffic. The
comparative analysis shows the influence of the traffic granularity on the
survivability cost: for high bandwidth LSPs, close to the optical channel
capacity, the multilayer survivability outperforms the single layer one,
whereas for low bandwidth LSPs the single layer survivability is more
cost-efficient. For the multilayer survivability we demonstrate that by mapping
efficiently the spare capacity of the MPLS layer onto the resources of the
optical layer one can achieve up to 22% savings in the total configuration cost
and up to 37% in the optical layer cost. Further savings (up to 9 %) in the
wavelength use can be obtained with the integrated approach to network
configuration over the sequential one, however, at the increase in the
optimization problem complexity. These results are based on a cost model with
actual technology pricing and were obtained for networks targeted to a
nationwide coverage
Survivable MPLS Over Optical Transport Networks: Cost and Resource Usage Analysis
In this paper we study different options for the survivability implementation
in MPLS over Optical Transport Networks (OTN) in terms of network resource
usage and configuration cost. We investigate two approaches to the
survivability deployment: single layer and multilayer survivability and present
various methods for spare capacity allocation (SCA) to reroute disrupted
traffic. The comparative analysis shows the influence of the offered traffic
granularity and the physical network structure on the survivability cost: for
high bandwidth LSPs, close to the optical channel capacity, the multilayer
survivability outperforms the single layer one, whereas for low bandwidth LSPs
the single layer survivability is more cost-efficient. On the other hand,
sparse networks of low connectivity parameter use more wavelengths for optical
path routing and increase the configuration cost, as compared with dense
networks. We demonstrate that by mapping efficiently the spare capacity of the
MPLS layer onto the resources of the optical layer one can achieve up to 22%
savings in the total configuration cost and up to 37% in the optical layer
cost. Further savings (up to 9 %) in the wavelength use can be obtained with
the integrated approach to network configuration over the sequential one,
however, at the increase in the optimization problem complexity. These results
are based on a cost model with different cost variations, and were obtained for
networks targeted to a nationwide coverage
Priority based dynamic lightpath allocation in WDM networks.
Internet development generates new bandwidth requirement every day. Optical networks employing WDM (wavelength division multiplexing) technology can provide high capacity, low error rate and low delay. They are considered to be future backbone networks. Since WDM networks usually operate in a high speed, network failure (such as fiber cut), even for a short term, can cause huge data lost. So design robust WDM network to survive faults is a crucial issue in WDM networks. This thesis introduces a new and efficient MILP (Mixed Integer Linear Programming) formulation to solve dynamic lightpath allocation problem in survivable WDM networks, using both shared and dedicated path protection. The formulation defines multiple levels of service to further improve resource utilization. Dijkstra\u27s shortest path algorithm is used to pre-compute up to 3 alternative routes between any node pair, so as to limit the lightpath routing problem within up to 3 routes instead of whole network-wide. This way can shorten the solution time of MILP formulation; make it acceptable for practical size network. Extensive experiments carried out on a number of networks show this new MILP formulation can improve performance and is feasible for real-life network. Source: Masters Abstracts International, Volume: 43-01, page: 0249. Adviser: Arunita Jaekel. Thesis (M.Sc.)--University of Windsor (Canada), 2004
A segmentation method for shared protection in WDM networks
Shared link and shared path protections have been recognized as preferred schemes to protect traffic flows against network failures. In recent years, another method referred to as Shared Segment Protection has been studied as an alternative solution for protection. This method is more flexible and efficient in terms of capacity utilization and restoration time. However, to our best knowledge, this method has mostly been studied in dynamic provisioning scenarios in which searching for restoration paths is dynamically performed after a failure has occurred. In this paper, based on the path segmentation idea, we propose a method to generate good candidate routes for traffic demands in static provisioning. These candidates are used as input parameters of an Integer Linear Programming (ILP) model for shared backup protection. Numerical results show that the capacity efficiency resulting from these candidates is much better than the best known Shared Backup Path Protection (SBPP) schemes. In addition, although the restoration time of our scheme is a little bit longer than those implementing link protection, it is still faster than path protection schemes
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