Method for updating route in network, network device, and system

1. A method for updating a route in a network, the method comprising:

setting up, by a first network device of the network, a correspondence between an Internet Protocol (IP) network segment and a first IP address, wherein the first IP address is an IP address of the first network device, wherein the network further comprises a second network device and a third network device, the third network device being connected to the first network device and the second network device;

sending, by the first network device, a first link state advertisement (LSA) packet to the third network device, wherein the first LSA packet comprises a second IP address, wherein the first LSA packet is used to trigger the third network device to generate a first route whose destination address is the second IP address, wherein the second IP address belongs to the IP network segment, and wherein a next-hop IP address of the first route is the first IP address; and

sending, by the first network device, a second LSA packet to the third network device in response to the first network device determining that switching is to be performed on a next hop of a route stored in the third network device, whose destination IP address belongs to the IP network segment, and whose next-hop IP address is the first IP address, wherein the second LSA packet comprises the first IP address and is used to trigger the third network device to update, from the first IP address to a third IP address, wherein the next-hop IP address of the first route, and wherein the third IP address is an IP address of the second network device.

2. The method according to claim 1 , wherein the method further comprises:

sending, by the first network device, a third LSA packet to the third network device, wherein the third LSA packet comprises the first IP address, and wherein the third LSA packet is used to trigger the third network device to generate a route whose destination address is the first IP address; and

correspondingly, wherein using the second LSA packet to trigger the third network device to update, from the first IP address to a third IP address, the next-hop IP address of the first route comprises:

instructing, using the second LSA packet, the third network device to delete the route whose destination address is the first IP address, to trigger the third network device to update the first route whose next-hop IP address is the first IP address, so that the next-hop IP address of the first route is updated from the first IP address to the third IP address, wherein the third network device stores a route whose destination address is the third IP address.

3. The method according to claim 1 , wherein the first IP address is an IP address of a logical interface of the first network device, and wherein a forwarding address in the first LSA packet is the first IP address.

4. The method according to claim 2 , wherein the first IP address is an IP address of a logical interface of the first network device, and wherein a forwarding address in the first LSA packet is the first IP address.

5. A route switching method in a network, the method comprising:

receiving, by a third network device of the network, a first link state advertisement (LSA) packet sent by a first network device of the network, wherein the first LSA packet comprises a second IP address, and wherein the second IP address belongs to an Internet Protocol (IP) network segment, wherein the network further comprises a second network device, wherein the third network device is connected to the first network device and the second network device, wherein a correspondence between the IP network segment and a first IP address is set up by the first network device, and wherein the first IP address is an IP address of the first network device; and

generating, by the third network device based on the first LSA packet, a first route whose destination address is the second IP address, wherein a next-hop IP address of the first route is the first IP address;

receiving, by the third network device, a second LSA packet sent by the first network device, wherein the second LSA packet is sent to the third network device in response to the first network device determining that switching is to be performed on a next hop of a route stored in the third network device, whose destination IP address belongs to the IP network segment, and whose next-hop IP address is the first IP address, wherein the second LSA packet comprises the first IP address; and

updating, by the third network device from the first IP address to a third IP address, the next-hop IP address of the first route based on the second LSA packet, wherein the third IP address is an IP address of the second network device.

6. The method according to claim 5 , wherein the method further comprises:

receiving, by the third network device, a third LSA packet sent by the first network device, wherein the third LSA packet comprises the first IP address;

generating, by the third network device based on the third LSA packet, a route whose destination address is the first IP address;

correspondingly, wherein updating, by the third network device from the first IP address to a third IP address, the next-hop IP address of the first route based on the second LSA packet comprises:

receiving, by the third network device, a fourth LSA packet sent by the second network device, wherein the fourth LSA packet comprises the third IP address;

generating, by the third network device based on the fourth LSA packet, a route whose destination address is the third IP address; and

updating, by the third network device based on the second LSA packet, the first route whose next-hop IP address is the first IP address, so that the next-hop IP address of the first route is updated from the first IP address to the third IP address.

7. The method according to claim 5 , wherein the first IP address is an IP address of a logical interface of the first network device, and wherein a forwarding address in the first LSA packet is the first IP address.

8. The method according to claim 5 , wherein the first IP address is an IP address of a logical interface of the first network device, and wherein a forwarding address in the first LSA packet is the first IP address.

9. A first network device, comprising:

a processing unit, configured to set up a correspondence between an Internet Protocol (IP) network segment and a first IP address, wherein the first IP address is an IP address of the first network device; and

a sending unit, configured to send a first link state advertisement (LSA) packet to a third network device, wherein the first LSA packet comprises a second IP address, wherein the first LSA packet is used to trigger the third network device to generate a first route whose destination address is the second IP address, wherein the second IP address belongs to the IP network segment, and wherein a next-hop IP address of the first route is the first IP address;

wherein the processing unit is configured to determine whether switching is to be performed on a next hop of a route that is stored in the third network device, whose destination IP address belongs to the IP network segment, and whose next-hop IP address is the first IP address;

wherein the sending unit is configured to send a second LSA packet to the third network device in response to the processing unit determining that switching is to be performed on the next hop of the route stored in the third network device, whose destination IP address belongs to the IP network segment, and whose next-hop IP address is the first IP address, wherein the second LSA packet comprises the first IP address, and is used to trigger the third network device to update, from the first IP address to a third IP address, the next-hop IP address of the first route, and wherein the third IP address is an IP address of a second network device; and

wherein the first network device, the second network device, and a third network device are in a same network, the third network device being connected to the first network device and the second network device.

10. The first network device according to claim 9 ,

wherein the sending unit is further configured to send a third LSA packet to the third network device, wherein the third LSA packet comprises the first IP address, and is used to trigger the third network device to generate a route whose destination address is the first IP address; and

correspondingly, wherein the second LSA packet is used to instruct the third network device to delete the route whose destination address is the first IP address, to trigger the third network device to update the first route whose next-hop IP address is the first IP address, so that the next-hop IP address of the first route is updated from the first IP address to the third IP address, wherein the third network device stores a route whose destination address is the third IP address.

11. The first network device according to claim 9 , wherein the first IP address is an IP address of a logical interface of the first network device, and wherein a forwarding address in the first LSA packet is the first IP address.

12. The first network device according to claim 10 , wherein the first IP address is an IP address of a logical interface of the first network device, and wherein a forwarding address in the first LSA packet is the first IP address.