Communication subsystem is crucial for cluster computing, which affects its efficiency, adaptability and scalability. Large-Scale applications require challenging communication performance and availability from cluster systems. Multi-Networking communication is a novel approach to improve the communication performance and availability by using multiple network links in parallel. In this paper, the effect of multi-process multiplexing one network link is analyzed, a dynamic link dispatch scheme is proposed, and the design and implementation of a multi-networking communication layer, MNC is introduced, which extends GM messaging layer, and supports multi-Myrinet parallel communication. MNC provides multi-process effectively exploiting the raw performance of multi-Myrinet, and improves the communication performance of application layer significantly. Compared with one-way Myrinet/GM environment, the communication bandwidth between MNC processes has increased by 34% on the PC cluster interconnected with 2-way Myrinet.