To eliminate the most common problem of the flooding of Address Resolution Protocol (ARP) messages in Ethernet, a new ARP proxy mechanism, taking account of hybrid environment of Software-Defined Network (SDN) and traditional network was proposed environment. In this mechanism, the advantage of network-wide view of SDN paradigm was used to register hosts information once accessing into the network and update the records in real-time by keeping trace of hosts' dynamics and network failure. Thus, most ARP request messages could be responded directly by the controller. The evaluation results show that this proposed scheme reserves the auto-configuration characteristic, which is transparent to hosts, compatible with the existed hardware without any changes, reduces network traffic and allows redundant links existed in network, so as to improve the scalability of the Ethernet.