A loop avoidance communications method, where a first provider edge (PE) device sends a first identifier to a second PE device through a first interface, the first PE device receives, through the first interface, a data packet from the second PE device including the first identifier. Then, the first PE device determines that a second interface associated with the first identifier is in a faulty state. In response to the determining that the second interface is in the faulty state, the first PE device avoids sending the data packet to the second PE device through the first interface, where the first PE device connects to a customer edge (CE) device using the second interface.