The share medium type hub in the front end is the single entry point of the cluster. The requests of the clients through the hub are broadcast to the nodes in back end of the cluster. Each node in the cluster includes the isomorphic network card, the packet-filtering module, the delay balance module and the TCP stack-processing module. The network card in each node of the cluster is configured with the same IP address and MAC address. The packet-filtering module filters the data packets selectively. The delay balance module intercepts all request packets and delays the request packets. After the delayed time, the delay balance module submits the request packet to the TCP stack-processing module for processing. The TCP stack-processing module sends the data packets back to the client end.