Energy-aware virtual topology reconfiguration under dynamic traffic

Abstract

In an IP over WDM network architecture, IP traffic is carried over a virtual topology (VT), composed of optical transparent channels called lightpaths. We propose an energy-efficient dynamic VT adaptation method with sleep mode, which allows changing only one lightpath connectivity at a time by dynamically monitoring the IP packet traffic load on each lightpath. In order to assure the connectivity of future traffic increase a high-load threshold is used. When the packet traffic load on a specific lightpath becomes higher than a threshold, a new lightpath is added to the virtual topology. However this congestion avoidance policy increases the power consumption by activating transponders in the network. Therefore at the same time lightly loaded lightpaths are eliminated in the virtual topology by using a low-load threshold. Energy-efficient virtual topology adaptation is achieved by traffic offloading considering both lightly loaded and heavily loaded links in the network. In this regard, high-and low-load threshold values need to be carefully determined in order to both gain power and ensure load balancing with keeping the stability of virtual connectivity at a reasonable level.We have analysed the power consumption of the network during 48-hours for different values of low-and high-load thresholds together with the impact of different threshold values on the stability of the virtual topology. We have shown that there is a trade-off between number of changes in the virtual topology and the energy-efficiency. Experimental results demonstrate that a good compromise can be achieved by adjusting the high-and low-load thresholds carefully. Keywords: Energy-efficiency, IP over WDM networks, optical WDM networks, virtual topology reconfiguration, dynamic traffic. INTRODUCTIONInternet has become a significant part of our daily life leading to a rapid increase in traffic rates. Power consumption per user is continuously increasing although power consumption per bit is decreasing with the evolution of power efficient devices in telecommunication networks. In order to meet the requirements of this increasing traffic demands, today's optical wavelength division multiplexing (WDM) networks as a backbone transmission system, is designed to be over-dimensioned, with extra switching capacity and excess number of deployed links, taking into account the peak rates and future growth of the traffic, resulting in waste of energy.In an IP over WDM network architecture, IP traffic is carried over a virtual topology (VT), composed of optical transparent channels called lightpaths. In transparent optical networks, lightpaths are the most power consuming elements due to the electro-optical operations during the add/drop. Generally, the intensity of traffic on lightpaths follows a daily traffic profile, decreases during the early hours of the morning, starts to increase again after 9 am, and peaks during the daytime. In different time zones, the peak traffic intensities occur at different times, relative to a global clock reference...

Energy-Efficient Lightpath Establishment in Backbone Optical Networks Based on Ant Colony Optimization

“…Due to its polynomial complexity, the algorithm can be used to re-design the virtual topology for different parts of the daytime [13] when the network load changes considerably. For example, different virtual topologies are required for the morning, evening, midnight and weekends and can be designed with low use of computing resources before the beginning of each specific time period.…”

Green optical backbone networks: virtual topology adaptation using a page rank‐based rating system

“…Simulations were conducted for 48 h, after a warm-up period of 2 days. Network traffic is modeled as in [3]. The algorithms have been tested for three different sets of thresholds: {60-20}, {70-20}, and {80-20}.…”

“…The results presented in [3] show that the maintenance of a static virtual topology during the network operation is not efficient on an energy consumption aspect. In optical backbone networks, a virtual topology is constructed over the physical topology, which is the set of established lightpaths that can route IP traffic flows from point to point.…”

“…In optical backbone networks, a virtual topology is constructed over the physical topology, which is the set of established lightpaths that can route IP traffic flows from point to point. The results presented in [3] show that the maintenance of a static virtual topology during the network operation is not efficient on an energy consumption aspect. Contrary, an adaptive virtual topology scheme is more flexible as it can be adjusted on the current traffic load in order to reduce total energy consumption.…”

“…In [3] and [4], a virtual topology reconfiguration algorithm is presented using a two-load thresholds mechanism to detect overloaded and underutilized lightpaths. The reconfiguration scheme keeps the virtual topology in load balance by deactivating low-loaded lightpaths and activating new lightpaths when traffic congestion is detected.…”