Load balancing for single-address tenants

• US 8,805,990 B2
• Filed: 07/12/2012
• Issued: 08/12/2014
• Est. Priority Date: 07/12/2012
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Murthy, Ashwin, Patel, Parveen Kumar, Bansal, Deepak, Zikos, Marios
• Primary Examiner(s): KATSIKIS, KOSTAS J
• Application Number:
  US13/547,805
• Publication Number:
  US 20140019602A1
• Time in Patent Office: 761 Days
• Field of Search: 709220-224
• US Class Current: 709/223
• CPC Class Codes: G06F 15/173 using an interconnection network, e.g. matrix, shuffle, pyramid, star, snowflake
• CPC Class Codes: G06F 9/5083 Techniques for rebalancing the load in a distributed system
• CPC Class Codes: H04L 45/00 Routing or path finding of packets in data switching networks routing or path finding in wireless networks H04W40/00
• CPC Class Codes: H04L 45/38 Flow based routing
• CPC Class Codes: H04L 45/72 Routing based on the source address
• CPC Class Codes: H04L 45/76 Routing in software-defined topologies, e.g. routing between virtual machines
• CPC Class Codes: H04L 67/10 in which an application is distributed across nodes in the network software deployment G06F8/60; multiprogramming arrangements G06F9/46
• CPC Class Codes: H04L 67/1027 Persistence of sessions during load balancing
• CPC Class Codes: H04L 67/34 involving the movement of software or configuration parameters network booting or remote initial program loading [RIPL] G06F9/4416

Abstract

When a load balancer detects that a virtual address is associated with a single destination address, the load balancer sets a flag to distinguish the virtual address from virtual addresses that are associated with a plurality of destination addresses. The load balancer instructs the router to bypass the load balancer for network packets that are addressed to the virtual address, and refrains from storing subsequent flow state for the virtual address. When the virtual address is to be scaled up with an additional destination address, the load balancer sets a flag to distinguish the virtual address from virtual addresses that are associated with a single destination addresses. The load balancer instructs the router to route network packets that are addressed to the virtual address through the load balancer, instead of bypassing the load balancer, and starts storing flow state for the virtual address.

Claims

1. At a computer system that includes one or more processors and system memory, the computer system being configured as a load balancer that controls the routing of network packets between virtual addresses and destination addresses, a method for configuring load balancing for a virtual address, the method comprising:

an act of the load balancer detecting that a virtual address that is being managed by the load balancer is associated with only a single destination address;

in response to detecting, an act of the load balancer setting a flag for the virtual address to distinguish the virtual address from other virtual addresses that are associated with a plurality of destination addresses;

in response to detecting, an act of the load balancer sending a configuration message to a router, the configuration message interpretable by the router as an instruction to send network packets that are addressed to the virtual address to the destination address in a manner that bypasses the load balancer;

subsequent to sending the configuration message to the router, an act of the load balancer refraining from storing subsequent flow state for the virtual address;

an act of the load balancer detecting that said virtual address that is being managed by the load balancer is to be scaled up from being associated with only a first destination address to being associated with at least an additional second destination address;

in response to detecting, an act of the load balancer setting a new flag for the virtual address to distinguish the virtual address from other virtual addresses that are associated with a single destination address;

in response to detecting, an act of the load balancer sending a new configuration message to a router, the new configuration message interpretable by the router as an instruction to send network packets that are addressed to the virtual address to the load balancer, and cease a previous practice to bypass the load balancer for network packets that are addressed to the virtual address; and

subsequent to sending the new configuration message to the router, an act of the load balancer storing flow state for said virtual address.

2. The method as recited in claim 1, wherein the single destination address is associated with a virtual machine.

3. The method as recited in claim 2, wherein the single destination address is a first single destination address and the configuration message is a first configuration message, and wherein the load balancer is also configured to:

detect that the virtual machine is now only associated with a second single destination address; and

in response to detecting, send a second configuration message to the router, the second configuration message interpretable by the router as an instruction to send network packets that are addressed to the virtual address to the second single destination address in a manner that bypasses the load balancer.

4. The method as recited in claim 1, wherein, subsequent to sending the configuration message to the router, an agent along a path between the router and the destination address:

receives a network packet that is addressed to the virtual address; and

translates the network packet so that it is addressed to the associated single destination address.

5. The method as recited in claim 4, wherein the agent resides at a virtualization host computer system.

6. The method as recited in claim 4, wherein the agent resides at a computer system that is associated with the destination address.

7. The method as recited in claim 4, wherein the agent detects whether the network packet was sent by the router or by the load balancer, and translates the network packet when it was sent by the router.

8. The method as recited in claim 4, wherein the agent translating the network packet comprises the agent performing a Network Address Translation (NAT) operation on the network packet.

9. The method as recited in claim 8, wherein the agent performing a NAT operation on the network packet comprises the agent changing a destination address of the network packet from the virtual address to the destination address.

10. The method as recited in claim 1, wherein the single destination address is associated with physical hardware.

11. The method as recited in claim 1, wherein the load balancer is also configured to:

detect that a virtual machine that is associated with the single destination address has migrated from a first virtualization host computer to a second virtualization host computer; and

in response to detecting, sending a configuration message to the router, the configuration message interpretable by the router as an instruction to send network packets for the virtual address to the second virtualization host computer.

12. At a computer system that includes one or more processors and system memory, the computer system being configured as a load balancer that controls the routing of network packets between virtual addresses and destination addresses, a method for scaling up load balancing for a virtual address from a single destination address to a plurality of destination addresses, the method comprising:

an act of the load balancer detecting that a virtual address that is being managed by the load balancer is to be scaled up from being associated with only a first destination address to being associated with at least an additional second destination address;

in response to detecting, an act of the load balancer setting a flag for the virtual address to distinguish the virtual address from other virtual addresses that are associated with a single destination address;

in response to detecting, an act of the load balancer sending a configuration message to a router, the configuration message interpretable by the router as an instruction to send network packets that are addressed to the virtual address to the load balancer, and cease a previous practice to bypass the load balancer for network packets that are addressed to the virtual address; and

subsequent to sending the configuration message to the router, an act of the load balancer storing flow state for the virtual address.

13. The method as recited in claim 12, wherein one or both of the first destination address or the second destination address is associated with a corresponding server.

14. The method as recited in claim 13, wherein the corresponding server for one or both of the first destination address or the second destination address comprises a virtual machine.

15. The method as recited in claim 13, wherein the corresponding server for one or both of the first destination address or the second destination address comprises physical hardware.

16. The method as recited in claim 13, further comprising an act of the load balancer probing one or both of the first destination address or the second destination address to ascertain health of the corresponding server.

17. The method as recited in claim 16, wherein the act of probing one or both of the first destination address or the second destination address comprises one or more of:

establishing a network connection with the corresponding server,

sending a ping message to the corresponding server, or

fetching a Hypertext Transfer Protocol (HTTP) Uniform Resource Locator (URL) at the corresponding server.

18. The method as recited in claim 16, wherein when the probing indicates that a particular corresponding server is not responding, the load balancer ceases sending network traffic to a destination address associated with the particular corresponding server.

19. The method as recited in claim 12, wherein the load balancer storing flow state for the virtual address comprises the load balancer storing information that identifies the destination address corresponding to active flows.

20. A computer system, comprising:

a router;

a load balancer, the load balancer being configured to;

detect that a virtual address of a tenant that is being managed by the load balancer is associated with only a single virtual machine instance of the tenant;

in response to detecting, set a flag for the virtual address to distinguish the virtual address from other virtual addresses that are associated with multi-address tenants;

in response to detecting, send a configuration message to the router, the configuration message interpretable by the router as an instruction to send network packets that are addressed to the virtual address to the virtual machine in a manner that bypasses the load balancer;

refrain from storing subsequent flow state for the virtual address;

detect that a virtual address that is being managed by the load balancer is to be scaled up from being associated with only a first destination address to being associated with at least an additional second destination address;

in response to detecting, set a new flag for the virtual address to distinguish the virtual address from other virtual addresses that are associated with a single destination address;

in response to detecting, send a new configuration message to the router, the new configuration message interpretable by the router as an instruction to send network packets that are addressed to the virtual address to the load balancer, and cease a previous practice to bypass the load balancer for network packets that are addressed to the virtual address; and

subsequent to sending the new configuration message to the router, store flow state for the virtual address; and

a virtualization host computer system that is configured to execute the virtual machine instance, the virtualization host computer system including a host agent that is configured to;

detect that a network packet is addressed to the virtual address, and

translate the network packet to be addressed to the virtual machine instance.