If the fault is caused by incorrect configuration or networking environment, change the configuration or networking environment. Check whether the optical modules are Huawei-certified ones. If not, contact the. This document describes how to check the switch interface or port status and how to locate an interface physically down fault and restore the interface to the up state. Hardware failures: include hardware. We have a fibre run, SM, 650 meters, with Level1 dumb switches at each end, I get Link lights at both ends, but there's no network traffic. An interface may go down in many situations. An OLT equipped with a ETH board for upstream transmission is used as an example here.