A packet sending method includes that a first network device receives a first packet from a customer edge (CE) device, where the first packet includes a first Internet Protocol (IP) version 6 (IPv6) header and a first payload, and the first IPv6 header includes a source address (SA) and a destination address (DA); determines, according to an entry, an address identifier corresponding to the SA and the DA, where the entry includes a correspondence between the SA and the DA and the address identifier; updates the first IPv6 header in the first packet to a second IPv6 header to obtain a second packet; encapsulates the second packet using the address identifier to obtain an encapsulated packet, the address identifier is located at an outer layer of the second packet; and sends the encapsulated packet to a second network device.