A routing method, comprising: receiving, by a first mobility router of a mobile IP network, a first data packet sent by a first mobile node of the mobile IP network to a first communication peer end located in an external fixed network, wherein the first mobility router is a mobility router in a visited network of the first mobile node, and the first data packet comprises an address of the first communication peer end; acquiring, by the first mobility router, an address of a proxy routing entity of the mobile IP network based on the address of the first communication peer end, wherein the proxy routing entity is a router or a gateway located on a border of the mobile IP network and is located in a communication path between the first mobility router in the mobile IP network and the first communication peer end in the external fixed network; establishing, by the first mobility router, a first tunnel to the proxy routing entity based on the address of the proxy routing entity, so that subsequent data between the first mobile node and the first communication peer end is forwarded by using the tunnel, wherein the establishing, by the first mobility router, a first tunnel to the proxy routing entity based on the address of the proxy routing entity comprises: establishing, by the first mobility router, a binding relationship among the address of the first communication peer end, the address of the proxy routing entity, an address of the first mobile node, and tunnel information of the first tunnel; and sending, by the first mobility router, a tunnel establishment request message to the proxy routing entity, wherein the tunnel establishment request message comprises an address of the first mobility router, the address of the first communication peer end, and the address of the first mobile node, so that a binding relationship among the address of the first mobility router, the address of the first communication peer end, the address of the first mobile node, and the tunnel information of the first tunnel is established in the proxy routing entity; and transmitting, by the first mobility router by using the first tunnel, a data packet sent by the first communication peer end to the first mobile node. receiving, by a first mobility router of a mobile IP network, a first data packet sent by a first mobile node of the mobile IP network to a first communication peer end located in an external fixed network, wherein the first mobility router is a mobility router in a visited network of the first mobile node, and the first data packet comprises an address of the first communication peer end; acquiring, by the first mobility router, an address of a proxy routing entity of the mobile IP network based on the address of the first communication peer end, wherein the proxy routing entity is a router or a gateway located on a border of the mobile IP network and is located in a communication path between the first mobility router in the mobile IP network and the first communication peer end in the external fixed network; establishing, by the first mobility router, a first tunnel to the proxy routing entity based on the address of the proxy routing entity, so that subsequent data between the first mobile node and the first communication peer end is forwarded by using the tunnel, wherein the establishing, by the first mobility router, a first tunnel to the proxy routing entity based on the address of the proxy routing entity comprises: establishing, by the first mobility router, a binding relationship among the address of the first communication peer end, the address of the proxy routing entity, an address of the first mobile node, and tunnel information of the first tunnel; and sending, by the first mobility router, a tunnel establishment request message to the proxy routing entity, wherein the tunnel establishment request message comprises an address of the first mobility router, the address of the first communication peer end, and the address of the first mobile node, so that a binding relationship among the address of the first mobility router, the address of the first communication peer end, the address of the first mobile node, and the tunnel information of the first tunnel is established in the proxy routing entity; and establishing, by the first mobility router, a binding relationship among the address of the first communication peer end, the address of the proxy routing entity, an address of the first mobile node, and tunnel information of the first tunnel; and sending, by the first mobility router, a tunnel establishment request message to the proxy routing entity, wherein the tunnel establishment request message comprises an address of the first mobility router, the address of the first communication peer end, and the address of the first mobile node, so that a binding relationship among the address of the first mobility router, the address of the first communication peer end, the address of the first mobile node, and the tunnel information of the first tunnel is established in the proxy routing entity; and transmitting, by the first mobility router by using the first tunnel, a data packet sent by the first communication peer end to the first mobile node.