Information Technology Reference
In-Depth Information
Keywords:
WDM optical networks, unicast/multicast traffic protection schemes, network
complexity, blocking percentage
1.
I
NTRODUCTION
Network and service availability is one of the chief necessities in modern
telecommunication networks [1]. In other words, network survivability is an important
concern for high-speed WDM optical networks. Due to the ever increasing popularity of
bandwidth-intensive applications such as online gaming; video conferencing; e-commerce;
and e-learning; network traffic have increased exponentially in recent years [2]. Therefore, all
optical networks using Wavelength Division Multiplexing (WDM) technique are fast coming
out as the most suitable option for the next generation networks. WDM is a technique that can
harness the enormous bandwidth attainable in an optical fiber to satisfy the network
requirements. Optical networks using the WDM technology enable the transfer of several
Gbps of data on each fiber link in the network. There are two types of failures in WDM
networks: link failure and node failure. Respecting improved modern switching devices, link
failure is more concern than node failure. Therefore, the single link failure model attracts
more attention in the optical survivability research. Therefore, the single link failure can lead
to the loss of huge amount of data. Hence, network survivability at the event of link failures is
a major concern in WDM networks.
In real world applications, the protection against network failures plays an important role.
Network operators would like to ensure that their services are trustworthy and protected
against possible cable cuts or failures of various devices used in the network. Since a service
or a connection gets unattainable as soon as one of the dedicated networks components
becomes unavailable by a failure or imperfection [1], it is necessary to improve suitable
protection schemes to avoid or decrease data losses.
Protections schemes have been widely studied in the literature. The complete survey of
p-
cycle
schemes has been reviewed in [3] and [4]. The protection schemes for WDM mesh
networks and WDM ring networks have been reviewed until 2002 in [5]. Shared protection
has been reviewed in [6]. A survey on survivability methods on IP/WDM networks has been
provided in [7]. Finally, a limited survey on multicast protection schemes has been presented
in [8] and [43]. Although ring is the common physical topology for metro networks, mesh
networks are suitable for both metro and wide area networks. In a mesh network, however,
survivability is more complex than in a ring topology because of the greater number of
routing paths and design decisions that must be taken into consideration [5]. Due to its
importance, we provide a comprehensive study on the protection schemes suitable for WDM
mesh networks in this chapter. We consider both the protection schemes supporting unicast
traffic and the protection schemes supporting multicast traffic.
Before detailing the aforementioned schemes, we would like to define some of the
terminologies that will be used throughout this chapter as:
•
Restoration:
restoration is a dynamic mechanism where the backup path will not be
setup unless a failure occurs.
