This application provides a packet transmission method and apparatus. The method includes: receiving, by a first transmission device, a first VXLAN packet sent by a first service device through a first virtual extensible local area network VXLAN tunnel; determining, by the first transmission device, first egress information corresponding to a first BD and a first destination media access control MAC address, based on a correspondence between the first BD, the first destination MAC address, and the first egress information; generating, by the first transmission device, a second VXLAN packet based on the first VXLAN packet and the first egress information, where the second VXLAN packet includes a second VNI and an Ethernet frame; and sending, by the first transmission device sends the second VXLAN packet to a second transmission device through a second VXLAN tunnel. This application facilitates more flexible packet transmission.