A distributed control protocol for wavelength routing with fairness improvement in WDM networks

This paper considers the problem of distributed routing with fairness improvement in wavelength-routed wavelength-division multiplexed (WDM) networks with dynamic traffic conditions. The wavelength continuity constraint imposed by WDM networks causes increased blocking of connection requests. The performance loss is more for connections with longer hop counts, when compared to that for connections with shorter hop counts. This is further worsened when distributed routing is used due to the reservation conflicts. We propose a distributed control protocol to select a usable wavelength and route and to improve fairness among connections with different hop counts. The proposed dynamic priority based fairness improvement scheme(DPFS) improves fairness among connections by enforcing dynamically varying priority based control to the connection requests over access to a subset of the available wavelengths, while allowing a free access to the remaining wavelengths. We study the effectiveness of the proposed protocol through extensive simulation experiments. The results show that the proposed scheme improves fairness significantly with an acceptable level of degradation in the overall network performance.