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End-to-end Measurement Based connection Admission Control (EMBAC) mechanisms have been proposed to support real-time flows quality of service requirements over a Differentiated Services Internet architecture. The EMBAC basic idea is to decentralize the admission control decision, by requiring each individual user to probe the network path during flow setup, and by basing the accept/reject decision on the probing traffic statistics measured at the destination. In conformance with the differentiated services framework, routers are oblivious to individual flows and only need to serve data packets with a higher priority than probing traffic. In this paper, we build upon the observation that some form of congestion control of the probing packets queue at each router is a key factor to provide performance effective EMBAC operation. The original contribution of the paper is twofold. First, we provide a thorough investigation, by means of both approximate analytical modeling and extensive simulation, of an EMBAC scheme (denoted in the following EMBAC-PD), in which probing queues congestion control is enforced by means of a probing packet expiration deadline at each router. Second, by means of extensive performance evaluation, we show that EMBAC-PD can provide strict QoS guarantees even in the presence of very light probing overhead (few probing packets per flow setup). Most interesting, EMBAC-PD does not necessarily require long probing phases to accurately estimate the network load subject to statistical fluctuations, but can provide effective operation even in the presence of extremely short probing phase duration (e.g., few hundreds of ms, acceptable for practical applications).