A method includes: receiving a current data packet of a target service; adding detection indication information to the current data packet, to obtain a target data packet, where the detection indication information includes a target phase category corresponding to the current data packet, the target phase category is used to indicate a target phase in at least one key phase in which the current data packet is located in the target service, and the detection indication information is used to indicate to detect the current data packet; and transmitting the target data packet to a next hop node.