This paper focuses on parallel data transmission, which is one of the solutions in considering high-speed transmission in next generation wide area layer-2 network. To realize parallel data transmission, reliable delay and route measuring for every possible path between two nodes and choosing multiple paths with small delay difference is necessary. This paper proposes a new multipath discovery and delay measurement method using bi-directional flooding technique. In the proposed method, extended Ethernet frame and bi-directional flooding technique which runs on data plane is introduced. The computer simulation showed that by applying the proposed bi-directional flooding technique, scalability has been greatly increased.