Simulation Studies of Communication Systems with Mutual Overflows and Threshold Mechanisms

In the article, the research results on the effectiveness of overflow technique in multi-service networks have been presented. Two kinds of overflows have been considered: overflow between primary resources (the same level of hierarchy), i.e., mutual overflow; and traffic overflow between primary and secondary resources, i.e., hierarchical overflow. In the first place, a traffic offered to the specific primary resources, when they are busy, is forwarded to neighboring primary resources. In the case, when the request cannot be handled by any of primary resources, it is overflowed to secondary resources. Additionally, in the research threshold compression mechanism was considered, according to which - for certain levels of resource occupancy - a reduced amount of resources is allocated for new requests in respect to the requested amount. The effectiveness of the overflow and compression mechanisms has been evaluated using the blocking probability, number of the served requests and amount of the carried traffic. The outcome of the work can be used in planning and dimensioning of multi -service systems with separated resources, e.g. in data centres.