In this paper, an architecture of software environment to offload user-defined software modules to Maestro2 cluster network, named Maestro dynamic offloading mechanism (MDO), is described. Maestro2 is a high-performance network for clusters. The network interface and the switch of Maestro2 have a general-purpose processor tightly coupled with a dedicated communication hardware. MDO enables the users to offload software modules to both the network interface and the switch. MDO includes a wrapper library with which offload modules can be executed on a host machine without rewriting the program. The overhead and the effectiveness of MDO are evaluated by offloading collective communications.