With the introducing of BroadR-Reach and TSN, Ethernet generally become one of IVN (in-vehicle network). Although it has been used in IT field for decades, it is a new technology for automotive thus need necessitate extensive testing. Current test solutions usually target for specific specification rather than in-vehicle environment. It means some characters are still uncertain for in-vehicle usage (e.g. fault tolerant ability for wires short or break). However, these characters must be cleared before apply Ethernet for IVN due to its stringent safety requirements. Since CAN is usually used for these environment, automotive Ethernet is expected to have same or better level fault-tolerant ability. Both CAN and BroadR-Reach use 1 pair of twisted wires for physical media, it means the traditional fault-tolerant test method can still apply for automotive Ethernet. However, due to the new transceiver circuit, some test methods need to be modified as required. This paper analysis the physical communication mechanism for BroadR-Reach and testing compare to CAN bus. Test cases such as wire short to BAT/GND, ground shift and load capacity are applied to TJA1100 from NXP. Although these test results are related to chip manufacturers and production batches, the analysis results still have guiding significance for the usage of automotive Ethernet to avoid dangerous conditions.