With the booming development of terrestrial network, scaling terrestrial network over satellite network to build Integrated Ter-restrial-Satellite Network (ITSN) and mean-while to provide the global Intet access, has become ever more attractive. Naturally, the widely and successfully used terrestrial rout-ing protocols are the promising protocols to integrate the terrestrial and satellite networks. However, the terrestrial routing protocols, which rely on propagating routing messages to discover New Network Topology (NNT) in the terrestrial network with rare topology chang-es, will suffer from overly numerous routing messages in satellite network whose topology frequently changes as satellites move. In this paper, a Topology Discovery Sub-layer for ITSN Routing Schemes (TDS-IRS) is firstly proposed to avoid the propagation of numer-ous routing messages by taking advantage of the movement predictability of satellite and the requirements of routing schemes to dis-cover NNT in advance of topology change. Secondly, a Weighted Perfect Matching based Topology Discovery (WPM-TD) model is designed to conduct the NNT discovery on the ground. Thirdly, this paper builds a test-bed with real network devices and meanwhile interconnect that testbed with real Intet, to validate that RS-TDS can discover NNT immediately with the less on-board overhead compared with optimized routing schemes. Fi-nally, different network scenarios are applied to validate the WPM-TD, i.e., the core module of TDS-IRS. Extensive experiments show WPM-TD can work efficiently, avoiding the invalid NNT discovery and decreasing 20% ~57% of potential topology changes, which can also improve up to 47% ~ 105% of network throughput.