Design of p-Cycles for full node protection in WDM Mesh Networks



  Design of p.pdf (Size: 1.18 MB / Downloads: 6)
INTRODUCTION

WDM techniques enable a single fiber to carry multiple
non-overlapping channels, and a single channel can operate
at the speed of up to 100 Gbps. WDM networks carry huge
amounts of traffic. As optical WDM networks are occasionally
prone to a single failure of network infrastructure (e.g., a fiber
cut or a node failure), survivability is an essential requirement
in the design of WDM networks.


NODE AND LINK PROTECTION p-CYCLES

We introduce the concept of overlapping p-cycles in order
to ensure 100% node protection. It generalizes the node
protection proposed in [7] in two respects: firstly, the node
protection is embedded in the generation and the protection
provisioning of the p-cycles and does not require a second
optimization step once the (link) p-cycles have been selected,
and secondly, p-cycles can handle the node protection of nodes
even if they are crossed by several paths as long as those paths
require independent protection from the p-cycle. As we will
see in the numerical results, this allows reducing the spare
bandwidth requirement.


Node protection in overlapping p-cycles

The overlapping p-cycle concept is alike the concept of
overlapping segment protection. Indeed, while segment protection
has been introduced as a compromise between page link and
path protection, there are two types of segment protection, the
regular segment protection when protection segments have the
same endpoints as the working segment, and the overlapped
segment protection where segments overlap in order to guarantee
node protection in addition to page link protection, see Jaumard
et al. [12]. We investigate here the overlapping of p-cycles in
order to guarantee 100% node protection.


The pricing problem
The goal of the pricing problem is to generate a promising
p-cycle that would decrease the value of the current solution
of the master problem. The pricing problem corresponds to the
optimization problem with the objective of minimizing the socalled
reduced cost of the master problem subject to a set of
constraints for the generation of a p-cycle and for its set of
protected links/nodes.


Data instances
We carry out experiments on five network instances for
evaluation and comparison. Table I presents the network
instances and their associated topology characteristics. For
each network, we provide the number of nodes, the number
of links, and the average nodal degree (as an indicator for
the network connectivity). Moreover, we give the number of
demand requests and working capacity usage (the number
of page link wavelength channels) for each traffic instance.


CONCLUSION
In this paper, we study the p-cycle design in WDM mesh
networks for full page link and node protection against a single
failure. We showed that it is possible to modify the p-cycle
design so as to ensure 100% node protection.