The interconnected architecture of software defined network (SDN) and traditional IP network we propose is based on the following core idea: taking the SDN as a traditional “route”. The network layer reachability information (NLRI) of the entire network becomes consistent after “route” communicates with IP network by exchanging NLRI through the border gateway protocol (BGP ). We design an interconnected architecture based on the above idea. Besides, we test the models’ functions, and verify the validity of interconnected architecture in the multi-SDN scene and the performance. Simulation results show that the interconnected architecture can make the SDN and traditional IP network interconnect and communicate normally. The proposed interconnected architecture makes little change to network devices, and the changes mainly focus on the SDN controller which is software programmable, and it is helpful for this technology to be deployed and implemented in the real network environment.