Bandwidth is a key resource in cloud networks. Every tenant wants to be assigned the bandwidth which is proportional to the price they have paid. At the cloud vender side, the link bandwidth utilization could be enhanced to support more clients. In this paper, we show that the traditional PS-N (Proportional Sharing at Network level) bandwidth allocation algorithm cannot achieve the network proportionality fairness when the network is over-subscribed. PPSN (Persistence Proportional Sharing at Network level) is proposed to solve the unfairness issue. However, the bandwidth utilization of both algorithms is not good enough to meet venders' demands. BEPPS-N (Bandwidth Efficiency Persistence Proportional Sharing at Network level) is thus proposed to enhance the bandwidth utilization by assigning more bandwidth to the communication pairs that are not passing through bottleneck links, and at the same time, keep proportionality fairness per different tenant. Finally, simulations and performance analysis have been conducted to substantiate the viability of our proposed approach.