Fairness in Überlastsituationen mittels Proof-of-Work-Funktionen

This work shows that overload handling will always be necessary regardless of future improvements in hardware performance. The most difficult part when constructing a fair overload handling system is that in today’s internet infrastructure one can no more identify a single client by its IP address. The proposed solution is based on so called Proof-Of-Work functions. Thus, a client willing to send a request to the server in overload has to provide the solution to a computational puzzle which brakes down malicious clients and guarantees a fairer distribution of resources. The related work concerning Proof-Of-Work functions is discussed and the HashCashLin function is developed as an answer to weaknesses concerning parameterization among existing POW functions. A three layer controller is designed which allows to adapt the hardness of the POW in order to precisely control the overload of a server. Using a simulation the functionality of the approach is studied. The results show that the POW system works much fairer than