The Contention Resolution in OBS Network
Keywords: Analytical models, burst switching, optical wavelength conversion, scheduling algorithms, wavelength routing
AbstractBurst contention occurs when attempting to transmit several optical bursts at the time into the same core router output port. This is a shortcoming of the Optical Burst Switching (OBS) networks and for this reason it has been challenging to implement the OBS mode into the transport networks so far. This problem can be solved applying various contention resolution strategies at core nodes (fiber delay lines, wavelength conversion or deflection routing). The following question arises: how does data transmission through the OBS network quality depend on using such strategy combination in the core node? For these reasons an analytical model has been created to find out what impact a joint application of various contention resolution strategies has on the data transmission quality. An algorithm has been proposed for the burst service in the OBS core router when a contention arises. The authors suggest applying burst segmentation only for the lower priority bursts, reducing the lower priority data losses in the case of mixed priority burst incoming flow. Every additional burst collision resolution strategy increases the time spent at the node however, so it is highly important to determine by means of simulations the optimal amount of resources needed at the core node.
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