Internet2 community was initiated by National Research and Education Networks (NRENs) that peers with each other at IP Layer. With the explosive growth of traffic demands from E-Science applications, optical networks has been introduced in late 90s for exploring higher bandwidth and better QoS guarantee. Problems arise when integrating the whole new optical infrastructure with current IP backbone, including controlling data path and network management. In this paper, we focus on fault management issue in hybrid networks containing DWDM, SDH and IP technologies. For instance, when there is a fiber cut in DWDM layer, tens of alarms would appear concurrently indicating network breakdowns in DWDM, SDH and IP layer separately, which will confuse engineers for error locating. Therefore, we experiment with several scenarios and propose a novel correlation method among these layers according to correlation diagram. Our contribution would benefit NRENs with hybrid networks for root-cause finding among alarms cross different network layers.