||In a high-speed backbone network, each node may act as a router/gateway which connects several LANs as well as hosts. Usually, the routers/gateways might incur congestion due to the transmission rates between the high-speed backbone and the low-speed LANs being mismatched. Because the existance of high-speed LANs becomes possible, the congestion may occur on the routers owing to the limitation of transmission rate to access the backbone network and available buffer spaces on it. To release the congestion, it is desirable to have some congestion control algorithms for the routers. In this paper, we propose a simple and efficient congestion control MAC protocol for dual bus high-speed networks. Based on this protocol, all the buffers in the network can be fully shared so that the transmission rate of each node is proportional to its load. In other words, a heavy loaded node obtains a faster transmission rate to send the packets in its buffer so that the congestion can be prevented. At the same time, each of the uncongested nodes will slow down its transmission and store the new incoming messages into its buffer. This implies that the buffers on the network can be shared dynamically. Simulation results show that compared to the DQDB MAC protocol, the proposed protocol significantly reduces the message queueing delay and message loss rate, and provides an attractive high throughput in the backbone network.