Network system, layer 3 communication device, layer 2 communication device, and route selection method

• US 20060209895A1
• Filed: 09/15/2005
• Published: 09/21/2006
• Est. Priority Date: 03/15/2005
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Hirota, Masaki
• Granted Patent: US 7,983,190 B2
• Time in Patent Office: Days
• US Class Current: 370/469
• CPC Class Codes: H04L 12/4641 Virtual LANs, VLANs, e.g. virtual private networks [VPN] LAN interconnection over a bridge based backbone H04L12/462; encapsulation techniques H04L12/4633; routing of packets H04L45/00; packet switches H04L49/00; virtual private networks for security H04L63/0272
• CPC Class Codes: H04L 45/28 using route fault recovery
• CPC Class Codes: H04L 49/602 Multilayer or multiprotocol switching, e.g. IP switching

Abstract

In a layer 2 communication device included in multiple layer 2 networks, an identifying unit identifies a layer 3 control packet from among packets passing through, and an embedding unit embeds routing control information for the layer 2 network in the layer 3 control packet. In a layer 3 communication device connected to the multiple layer 2 networks, a selecting unit selects from the multiple layer 2 networks, an optimum L2 network, that is a layer 2 network forming an optimum communication route, based on a communication destination, and a setting unit sets a packet to be transmitted to the optimum L2 network.

Claims

1. A network system comprising:

a layer 2 communication device that is included in multiple layer 2 networks; and

a layer 3 communication device that performs communication through the multiple layer 2 networks, wherein

the layer 2 communication device includes

an identifying unit that identifies a layer 3 control packet from among packets passing through the layer 2 communication device; and

an embedding unit that embeds routing control information for the layer 2 network in the layer 3 control packet, and

the layer 3 communication device includes

a selecting unit that selects from the multiple layer 2 networks, an optimum L2 network, that is a layer 2 network forming an optimum communication route, based on the routing control information for the layer 2 network embedded in the layer 3 control packet; and

a setting unit that sets a packet to be transmitted to the optimum L2 network.

2. The network system according to claim 1, wherein the layer 3 communication device further includes

a replicating unit that replicates the control packet by a number of the multiple layer 2 networks, if the control packet is to be transmitted over the multiple layer 2 networks.

3. A layer 3 communication device connected to multiple layer 2 networks, comprising:

a selecting unit that selects from the multiple layer 2 networks, an optimum L2 network, that is a layer 2 network forming an optimum communication route, based on a communication destination; and

a setting unit that sets a packet to be transmitted to the optimum L2 network.

4. The layer 3 communication device according to claim 3, further comprising:

an analyzing unit that receives a layer 2 control packet, and analyzes a state of multiplicity of the layer 2 networks, based on information in the layer 2 control packet received.

5. The layer 3 communication device according to claim 3, wherein the multiple layer 2 networks are VLANs (Virtual Local Area Networks).

6. The layer 3 communication device according to claim 3, wherein

the setting unit removes layer 2 routing information from the packet, if the packet is a layer 2 control packet that has passed through a layer 2 network.

7. A layer 2 communication device that is included in a layer 2 network, comprising:

an identifying unit that identifies a layer 3 control packet from among packets passing through the layer 2 communication device; and

an embedding unit that embeds routing control information for the layer 2 network in the layer 3 control packet.

8. The layer 2 communication device according to claim 7, wherein

the routing control information embedded includes a number of steps of the layer 2 communication device, and

the embedding unit increments the number of steps by one, every time the layer 3 control packet passes through the layer 2 communication device.

9. The layer 2 communication device according to claim 7, wherein

the routing control information embedded includes a cost value assigned to each output port of the layer 2 communication device, and

the embedding unit increments the cost value embedded by a cost value of an output port, if the layer 3 control packet passes through the layer 2 communication device.

10. The layer 2 communication device according to claim 9, wherein the cost value is same for all the output ports.

11. The layer 2 communication device according to claim 9, wherein the cost value is different for each the layer 2 communication device.

12. The layer 2 communication device according to claim 7, wherein

the embedding unit embeds the routing control information for the layer 2 network in unused bits of a metric field of an update message of a Routing Information Protocol (RIP).

13. The layer 2 communication device according to claim 7, wherein

the embedding unit embeds the routing control information for the layer 2 network in unused bits of a metric field of a Link State Advertisement (LSA) of an Open Shortest Path First (OSPF).

14. A method for a network system that includes a layer 2 communication device that is included in multiple layer 2 networks, and a layer 3 communication device that performs communication through the multiple layer 2 networks, the method comprising:

identifying, performed by the layer 2 communication device, a layer 3 control packet from among packets passing through the layer 2 communication device;

embedding, performed by the layer 2 communication device, routing control information for the layer 2 network in the layer 3 control packet;

selecting, performed by the layer 3 communication device, from the multiple layer 2 networks, an optimum L2 network, that is a layer 2 network forming an optimum communication route, based on the routing control information for the layer 2 network embedded in the layer 3 control packet; and

setting, performed by the layer 3 communication device, a packet to be transmitted to the optimum L2 network.

15. The method according to claim 14, wherein the embedding includes embedding routing control information that includes a number of steps of the layer 2 communication device, and incrementing the number of steps by one, every time the layer 3 control packet passes through the layer 2 communication device, and

the selecting includes selecting a layer 2 network having a least number of steps, as the optimum L2 network.

16. The method according to claim 14, wherein

the embedding includes embedding routing control information that includes a cost value assigned to each output port of the layer 2 communication device, and incrementing the cost value embedded by a cost value of an output port, if the layer 3 control packet passes through the layer 2 communication device, and

the selecting includes selecting a layer 2 network having a least cost value, as the optimum L2 network.

17. The method according to claim 16, wherein the cost value of all the output ports is same for all the output ports.

18. The method according to claim 16, wherein the cost value of an output port is different in each layer 2 communication device.