This paper presents a new NoC QoS metrics modeling shaped on mesh architecture. The new QoS model is based on the QoS parameters. The goal of this work is to quantify buffering requirements and packet switching techniques in the NoC nodes by analyzing some QoS metrics such as End-to-End delays (EEDs) and packet loss. This study is based on simulation approach of a 4 × 4 mesh NoC behavior under multimedia communication process. It proposes a study of NoC switching buffer size avoiding packet drop and minimizing EED. Mainly, we focus on percent flit losses due to buffer congestion for a network loading. This leads to identify the optimal buffer size for the switch design. The routing approach is based on the Wormhole Routing method.