Link layer address resolution of overlapping network addresses

• US 8,904,041 B1
• Filed: 04/30/2012
• Issued: 12/02/2014
• Est. Priority Date: 04/30/2012
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Poutievski, Leon, Friedman, Barry, Vahdat, Amin
• Primary Examiner(s): Whipple, Brian P
• Application Number:
  US13/460,063
• Time in Patent Office: 946 Days
• Field of Search: None
• US Class Current: 709/245
• CPC Class Codes: H04L 2101/668 Internet protocol [IP] address subnets
• CPC Class Codes: H04L 49/25 Routing or path finding in a switch fabric
• CPC Class Codes: H04L 61/103 across network layers, e.g. resolution of network layer into physical layer addresses or address resolution protocol [ARP]
• CPC Class Codes: H04L 61/5007 Internet protocol [IP] addresses
• CPC Class Codes: H04L 61/5038 for local use, e.g. in LAN or USB networks, or in a controller area network [CAN]

Abstract

A system, apparatus, and method for link layer address resolution of overlapping network addresses is disclosed. In one aspect, the method performed on a first device includes receiving a first address resolution request from a second device, the first address resolution request having a sender network address and a target network address, wherein the target network address is an overlapping network address that is a gateway address of the second device and a network address of a third device, creating a first address resolution response having a sender link layer address associated with the first device, and sending the first address resolution response to the second device.

Claims

1. A method of link layer address resolution by a first device, the method comprising:

receiving a first address resolution request from a second device, the first address resolution request having a sender network address and a target network address, wherein the target network address is an overlapping network address that is a gateway address of the second device and a network address of a third device and the second device is directly addressable from the third device;

creating a first address resolution response having a sender link layer address associated with the first device; and

sending the first address resolution response to the second device, wherein the sender network address and the target network address of each of the response and the request are equal except for their least significant bit.

2. The method of claim 1, wherein the sender network addresses and the target network addresses each include 32 bits.

3. The method of claim 1, wherein the first address resolution request is sent using an Internet Protocol network stack and wherein the first address resolution request and the first address resolution response are each formatted using Address Resolution Protocol.

4. The method of claim 3, further comprising:

receiving a second address resolution request from the third device, the second address resolution request having a sender network address equal to the target network address of the first address resolution request.

5. The method of claim 4, wherein the sender network addresses and target network addresses are within a point-to-point subnet.

6. The method of claim 4, wherein the first device is not configured with the target network address of either the first address resolution request or the second address resolution request.

7. The method of claim 6, wherein the first device is configured with a management network address to enable configuration of the first device.

8. The method of claim 1, wherein the first device has a plurality of network ports, the method further comprising:

receiving a network packet from the second device, the network packet addressed to a network address not associated with the first device and addressed to a link layer address associated with the first device; and

sending the network packet to one of the plurality of network ports that is associated with the network address that the network packet is addressed to.

9. The method of claim 8, wherein the network packet is addressed to the third device.

10. The method of claim 1, wherein receiving the first address resolution request from the second device comprises:

identifying that the target network address is configured to be an overlapping network address if the target network address is a part of a point-to-point subnet or if a configuration of a network port of the first device that the second device is connected to indicates that the second device uses an overlapping network address.

11. The method of claim 1, wherein the link layer address associated with the first device is one of a link layer address of a port of the first device, a pre-determined link layer address, or a generic link layer address.

12. The method of claim 1, wherein the first device is associated with a controller that is configured to create the first address resolution response.

13. A network switch comprising:

at least one memory; and

at least one processor configured to execute instructions stored in the at least one memory to;

receive a first address resolution request from a first device, the first address resolution request having a sender network address and a target network address, wherein the target network address is an overlapping network address that is a gateway address of the first device and a network address of a second device and the second device is directly addressable from the first device,

create a first address resolution response having a sender link layer address associated with the network switch, and

send the first address resolution response to the first device, wherein the sender network address and the target network address of each of the response and the request are equal except for their least significant bit.

14. The network switch of claim 13, wherein the memory further includes instructions to:

receive one or more additional address resolution requests from a one or more additional devices, the one or more additional address resolution requests having at least one sender network address equal to the target network address of the first address resolution request or another one of the additional address resolution requests.

15. The network switch of claim 13, wherein the instructions to create the first address resolution response do not require the network switch to be configured with a network address.

16. The network switch of claim 15, wherein the link layer address is a generic address that the network switch is configured to recognize for accepting network packets for routing.

17. A network system comprising:

a network switch having at least one processor, at least one memory, and a plurality of network ports, the network switch operable to forward network packets between at least some of the plurality of network ports;

a plurality of devices, at least some devices of the plurality of devices each connected to at least one of the plurality of network ports and configured with a network address and a gateway address; and

at least one link layer address resolver capable of resolving the gateway address of at least one device of the plurality of devices to a link layer address associated with the network switch when that gateway address is also used as a network address for another device of the plurality of devices, wherein the network address and gateway address of at least some of the plurality of devices are within a point-to-point subnet, the link layer address resolver is incorporated into a controller and the link layer address resolver is configured to generate an address resolution response including the link layer address associated with the network switch, the address resolution response being generated in response to an address resolution request sent by one of the plurality of devices, wherein a sender network address and a target network address of each of the response and the request are equal except for their least significant bit.

18. The network system of claim 17, wherein the link layer address resolver is configured to generate the address resolution response by swapping the sender network address and the target network address of the address resolution request.

19. The network system of claim 17, wherein the link layer address resolver is incorporated into at least some of the plurality of devices, the link layer address resolver including a generic link layer address usable for all network packets having an overlapping network address sent via the network switch.

20. The network system of claim 17, wherein the link layer address resolver is incorporated into at least some of the plurality of devices, the link layer address resolver including at least one pre-determined entry identifying the link layer address of the network switch associated with the gateway address.