<span lang="en">Traffic monitoring is an increasingly important discipline for nowadays networking, as accounting, security and also Quality of Service (QoS) lay on it. Besides, traffic bandwidth has increased exponentially in the last few years, and high speed network monitoring is a challenging aim. Performance requirements are highly relevant for monitoring systems. In a previous work, our research group NQaS (Networking, Quality and Security) provided an architecture able to cope with high-speed traffic monitoring using commodity hardware. Its design was also intended to exploit the parallelism available. This paper shows the main features of this kernel-level monitoring system (ksensor) and presents an analytical model for a multiprocessor network traffic analysis system. The model which is based on Markov chains, evaluates the efficiency of the system. The goodness of the model will be checked by comparing analytical results with practical ones obtained in laboratory, using ksensor, which runs on a multiprocessor platform in the testing system.</span>