LOAD BALANCING ACROSS LAYER-2 DOMAINS

• US 20100302940A1
• Filed: 10/26/2009
• Published: 12/02/2010
• Est. Priority Date: 05/28/2009
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Greenberg, Albert, Maltz, David, Kern, Randy, Patel, Parveen, Yuan, Lihua
• Granted Patent: US 8,416,692 B2
• Time in Patent Office: Days
• US Class Current: 370/230
• CPC Class Codes: H04L 12/4633 Interconnection of networks using encapsulation techniques, e.g. tunneling
• CPC Class Codes: H04L 45/04 Interdomain routing, e.g. hierarchical routing
• CPC Class Codes: H04L 45/24 Multipath
• 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 67/1027 Persistence of sessions during load balancing

Abstract

The present application relates to network configurations and specifically to scalable load balancing network configurations. One implementation includes an external client coupled to a scalable load balancing system. The scalable load balancing system includes a load balancing layer that is configured to encapsulate individual incoming packets of a packet flow from the external client. The load balancing layer is further configured to route the incoming packets to target devices on the system. The target devices can span multiple IP subnets. The incoming packets can pass through one or more load balancers of the load balancing layer before reaching individual target devices. Individual target devices can be configured to route at least some outgoing packets of the packet flow to the external client without passing through any of the one or more load balancers.

Claims

1. A computer-readable storage media having instructions stored thereon that when executed by a processing device performs acts comprising:

spreading network packets among a series of modules;

encapsulating the network packets at individual modules;

choosing a target device to which the network packets are encapsulated using a state shared among the modules of the series; and

forwarding the network packets from the modules of the series.

2. The computer-readable storage media of claim 1, wherein the state shared among modules of the series is a key space of a consistent hash function.

3. The computer-readable storage media of claim 1, wherein individual network packets are spread among modules of the series using Equal-Cost MultiPath routing.

4. The computer-readable storage media of claim 1, further comprising monitoring the target device'"'"'s health.

5. The computer-readable storage media of claim 1, wherein the state shared among modules of the series is changed in response to a failure of the target device.

6. The computer-readable storage media of claim 1, wherein a number of modules of the series can be changed dynamically based on one or more of a load parameter or one or more other parameters without causing downtime for a provided service.

7. The computer-readable storage media of claim 1, wherein the target device is a member of a set of target devices, and in an instance where an indication is received that one or more existing target devices of the set will become unavailable or one or more new target devices are available, transitioning to a configuration that spreads network packets associated with future communications to a new set of target devices while continuing to send network packets associated with ongoing communications to the target devices of the set.

8. The computer-readable storage media of claim 1, wherein encapsulating the packets comprises internet protocol (IP)-in-IP encapsulation.

9. The computer-readable storage media of claim 6, wherein encapsulating the packets preserves one or more Virtual IP addresses to which the packets were sent.

10. The computer-readable storage media of claim 1, wherein individual modules use packet modification and internet protocol (IP) options to preserve a Virtual IP address to which the packets were sent.

11. A method comprising:

spreading network packets among a series of modules;

encapsulating an individual network packet at an individual module so as to preserve source and destination addresses of the individual network packet as received by the individual module;

choosing a target device to which the individual network packet is encapsulated to provide an encapsulated packet using a state shared among the modules; and

,

forwarding the encapsulated packet from the individual module for the target device.

12. The method of claim 11, further comprising:

receiving the encapsulated packet at the target device;

decapsulating and processing the encapsulated packet at the target device; and

responding to a source address of the encapsulated packet with one or more different network packets that do not traverse the individual module.

13. The method of claim 12, wherein the individual module uses packet modifications and internet protocol (IP) options to preserve source and destination addresses;

and wherein the target device responds to a source address contained in the IP options with one or more packets that do not traverse the individual module.

14. The method of claim 11, wherein the encapsulating is performed by a multiplexer of one or more network load balancers.

15. A system comprising:

a load balancing layer configured to encapsulate individual incoming packets of a packet flow from an external client device, the load balancing layer further configured to route the incoming packets to target devices of the system, wherein the target devices span one or more internet protocol (IP) subnets, and wherein the incoming packets pass through one or more load balancers of the load balancing layer before reaching individual target devices; and

,

the individual target devices configured to route at least some outgoing packets of the packet flow to the external client device without passing through any of the one or more load balancers.

16. The system of claim 15, wherein the load balancing layer is configured to encapsulate the individual incoming packets utilizing one or both of internet protocol (IP)-in-IP encapsulation or packet modification and IP options.

17. The system of claim 15, wherein the load balancing layer comprises at least one dynamic load balancer and at least one multiplexer and wherein the at least one multiplexer is configured to encapsulate the individual incoming packets.

18. The system of claim 15, wherein the load balancing layer comprises at least one multiplexer and wherein the at least one multiplexer is configured to encapsulate the individual incoming packets utilizing IP-in-IP encapsulation.

19. The system of claim 15, wherein the individual target devices include a decapsulation component configured to decapsulate packets from the load balancing layer or wherein individual target devices span multiple virtual local area networks.

20. The system of claim 15, wherein the one or more load balancers comprise dynamic load balancers that are configured to provide an application program interface to mange virtual IP (VIP) to direct IP (DIP) mappings of the load balancing layer.