Modelling and evaluation of QCN using coloured petri nets

Congestion management capability is an important requirement for any quality of services (QoS) networking technology. Therefore, IEEE 802.1Qau has proceeded a congestion notification project whose aim is to develop a Carrier Ethernet congestion control scheme at Layer 2 for a data center network. A data center network should be efficient and robust to handle the growing demands of cloud computing. A congestion control scheme is a key component of data transport in this kind of network. The quantized congestion notification (QCN) scheme is a congestion management scheme, which has been standardized and designed to be implemented in the Carrier Ethernet. Coloured Petri net (CPN) is a modelling technique used with the Petri nets modelling tool. This technique is exploited to model and simulate the QCN in order to help understand the QCN scheme and derive performance measures. This paper proposes a formal model for the QCN scheme. Then, we verify the implementation of our model by simulations. Thus, the QCN queue and rate performances are evaluated using the CPN tools. Moreover, an improved model called TAI-QCN is proposed in order to enhance the QCN scheme.