A packet sending method and apparatus, a network device, a system, and a storage medium are disclosed in the field of communication technologies. An edge network device of a tier-1 carrier that has upgraded to an SRv6 network establishes a mapping relationship between a segment identifier and an MPLS label. After receiving a packet that carries an MPLS label and that is sent by a network device of a tier-2 carrier, the edge network device generates, based on the mapping relationship, a packet carrying a segment identifier. The packet carrying the segment identifier is forwarded in the SRv6 network of the tier-1 carrier.