A RWA framework for improved throughput in OBS networks

Abstract

All-Optical Burst Switched (OBS) backbone transport networks facilitate connectionless transport utilizing wavelength division multiplexing of multiple lightpaths end-to-end channels. The data in such networks is transmitted in the form of bursts. However, whereas such networks provide capacities in the Terahertz ranges, the data bursts being ferried often contend with each other at intermediate (interior) buffer-less nodes. The frequent occurrences of both contentions, as well as wavelength congestions, are often characterized by degradations in overall network performance in handling moderate to high traffic levels, and all this is attributed to increases in burst losses. Whereas deflection routing contention resolution is quite popular in combating both contention and wavelength congestions to improve overall network throughput, it is however necessary that network throughput always balances with effective utilization. Further complexity is that of most practical backbone transport networks often being multi-domain in nature and thus necessitating the dimensioning of deflection routing resources for both interdomain and intra-domain traffic to avoid degradation of network performance in terms of contention as well as wavelength congestion occurrences in one domain due to improper dimensioning in the other(s). In this regard, a combination of appropriately designating border nodes and grooming interdomain traffic will vastly improve overall network performance as well as fairness to multiple domain lightpath connections. In this paper, we propose a prioritized (indexed) cooperativebased routing and wavelength assignment (PIC-RWA) scheme that couples with wavelength grooming for inter-border traffic to reduce both contention and wavelength congestions. Performance results indicate that it significantly improves overall network performance in terms of improved effective resources utilization.