A packet transmission method, wherein the method comprises: receiving, by a first Network Virtualization Edge, NVE, device, a first packet, wherein the first packet comprises a first source address and a first destination address, the first source address is an address of a first virtual machine, and the first destination address is an address of a second virtual machine, wherein the first virtual machine is virtualized by a first physical server and the second virtual machine is virtualized by a second physical server; obtaining, by the first NVE device, an active-active access configuration information list, wherein the active-active access configuration information list comprises a first entry and a second entry, wherein the first entry comprises an identifier of a first active-active group, a virtual network instance, and an identifier of the first NVE device, and the second entry comprises an identifier of a second active-active group, the virtual network instance, and identifiers of at least two NVE devices that belong to the second active-active group, and wherein the active-active access configuration information list is obtained by receiving the active-active access configuration information list; obtaining, by the first NVE device, the virtual network instance according to the first entry and the identifier of the first NVE device; searching, by the first NVE device, for at least one active-active group corresponding to the virtual network instance, wherein the at least one active-active group comprises the second active-active group; and selecting a second NVE device from the at least two NVE devices belonging to the second active-active group; and encapsulating, by the first NVE device, the first packet by using an identifier of the second NVE device and the virtual network instance, and sending the encapsulated first packet to the second virtual machine via the second NVE device. receiving, by a first Network Virtualization Edge, NVE, device, a first packet, wherein the first packet comprises a first source address and a first destination address, the first source address is an address of a first virtual machine, and the first destination address is an address of a second virtual machine, wherein the first virtual machine is virtualized by a first physical server and the second virtual machine is virtualized by a second physical server; obtaining, by the first NVE device, an active-active access configuration information list, wherein the active-active access configuration information list comprises a first entry and a second entry, wherein the first entry comprises an identifier of a first active-active group, a virtual network instance, and an identifier of the first NVE device, and the second entry comprises an identifier of a second active-active group, the virtual network instance, and identifiers of at least two NVE devices that belong to the second active-active group, and wherein the active-active access configuration information list is obtained by receiving the active-active access configuration information list; obtaining, by the first NVE device, the virtual network instance according to the first entry and the identifier of the first NVE device; searching, by the first NVE device, for at least one active-active group corresponding to the virtual network instance, wherein the at least one active-active group comprises the second active-active group; and selecting a second NVE device from the at least two NVE devices belonging to the second active-active group; and encapsulating, by the first NVE device, the first packet by using an identifier of the second NVE device and the virtual network instance, and sending the encapsulated first packet to the second virtual machine via the second NVE device.