Stateless distributed load-balancing

• US 10,511,534 B2
• Filed: 04/06/2018
• Issued: 12/17/2019
• Est. Priority Date: 04/06/2018
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Pfister, Pierre, Desmouceaux, Yoann, Townsley, William Mark
• Primary Examiner(s): Pezzlo, John
• Application Number:
  US15/947,425
• Publication Number:
  US 20190312811A1
• Time in Patent Office: 620 Days
• Field of Search: 370229, 370252, 370386, 370389
• CPC Class Codes: H04L 47/125 by balancing the load, e.g. traffic engineering
• CPC Class Codes: H04L 47/19 at layers above the network layer network arrangements for networked applications for scheduling or organising the servicing of application requests H04L67/60
• CPC Class Codes: H04L 47/34 ensuring sequence integrity, e.g. using sequence numbers
• CPC Class Codes: H04L 47/726 Reserving resources in multiple paths to be used simultaneously by balancing the load H04L47/125

Abstract

Aspects of the subject technology provide state-less load-balancing using sequence numbers to identify traffic flows. In some implementations, a process of the technology can include steps for receiving, by a load-balancer, a first packet from a source device including a request to access the service provided by a server coupled to the load-balancer, determining a load for each of the servers, wherein each server is associated with a unique set of sequence numbers, and forwarding the request to a target server selected based on its corresponding load, and wherein the request is configured to cause the target server to issue a reply to the source device. Systems and machine-readable media are also provided.

Claims

1. A computer-implemented method comprising:

receiving, by a load-balancer, a first packet from a source device, the first packet comprising a request to access a service provided by a server coupled to the load-balancer;

determining, by the load-balancer, a load for each of a plurality of servers, each of the plurality of servers is associated with a unique set of sequence numbers; and

forwarding the request to a target server selected from among the plurality of servers based on the load for each of the plurality of servers, the request configured to cause the target server to issue a reply to the source device, the reply comprising a sequence number selected from the unique set of sequence numbers corresponding with the target server,

wherein

the load-balancer includes a table associating each of the plurality of servers with its corresponding unique set of sequence numbers.

2. The computer-implemented method of claim 1, further comprising:

receiving, by the load-balancer, a second packet from the source device, wherein a header of the second packet contains the sequence number; and

routing, by the load-balancer, the second packet to the target server based on the sequence number in the header.

3. The computer-implemented method of claim 2, wherein routing the second packet to the target server includes:

identifying the target server as a destination for the second packet based on the sequence number; and

forwarding the second packet to the target server.

4. The computer-implemented method of claim 1, wherein the unique set of sequence numbers corresponding with the target server are Transmission Control Protocol (TCP) sequence numbers.

5. The computer-implemented method of claim 1, wherein the reply comprises at least one packet for which a packet header contains the sequence number.

6. The computer-implemented method of claim 1, wherein the load-balancer is configured to disregard state information for servers associated with active traffic flows.

7. A system comprising:

one or more processors;

a network interface coupled to the one or more processors, the network interface configured to transact data with a computer network; and

a non-transitory computer-readable storage medium coupled to the one or more processors, the non-transitory computer-readable storage medium containing instructions which, when executed by the one or more processors, cause the system to;

receive, by a load-balancer, a first packet from a source device, the first packet comprising a request to access a service provided by a server coupled to the load-balancer;

determine, by the load-balancer, a load for each of a plurality of servers, each of the plurality of servers is associated with a unique set of sequence numbers; and

forward the request to a target server selected from among the plurality of servers based on the load for each of the plurality of servers, the request configured to cause the target server to issue a reply to the source device, the reply comprising a sequence number selected from the unique set of sequence numbers corresponding with the target server,

wherein

the load-balancer includes a table associating each of the plurality of servers with its corresponding unique set of sequence numbers.

8. The system of claim 7, wherein the operations include:

receiving, by the load-balancer, a second packet from the source device, wherein a header of the second packet contains the sequence number; and

routing, by the load-balancer, the second packet to the target server based on the sequence number in the header of the second packet.

9. The system of claim 8, wherein routing the second packet to the target server includes:

identifying the target server as a destination for the second packet based on the sequence number; and

forwarding the second packet to the target server.

10. The system of claim 7, wherein the unique set of sequence numbers corresponding with the target server are Transmission Control Protocol (TCP) sequence numbers.

11. The system of claim 7, wherein the reply comprises at least one packet for which a packet header contains the sequence number.

12. The system of claim 7, wherein the load-balancer is configured to disregard state information for servers associated with active traffic flows.

13. A non-transitory computer-readable storage medium comprising instructions stored therein, which when executed by one or more processors, cause the one or more processors to perform operations comprising:

receiving, by a load-balancer, a first packet from a source device, the first packet comprising a request to access a service provided by a server coupled to the load-balancer;

determining, by the load-balancer, a load for each of a plurality of servers, each of the plurality of servers is associated with a unique set of sequence numbers; and

forwarding the request to a target server selected from among the plurality of servers based on the load for each of the plurality of servers, the request configured to cause the target server to issue a reply to the source device, the reply comprising a sequence number selected from the unique set of sequence numbers corresponding with the target server,

wherein

the load-balancer includes a table associating each of the plurality of servers with its corresponding unique set of sequence numbers.

14. The non-transitory computer-readable storage medium of claim 13, wherein the operations include:

receiving, by the load-balancer, a second packet from the source device, wherein a header of the second packet contains the sequence number; and

routing, by the load-balancer, the second packet to the target server based on the sequence number in the header of the second packet.

15. The non-transitory computer-readable storage medium of claim 14, wherein routing the second packet to the target server includes:

identifying the target server as a destination for the second packet based on the sequence number; and

forwarding the second packet to the target server.

16. The non-transitory computer-readable storage medium of claim 13, wherein the unique set of sequence numbers corresponding with the target server are Transmission Control Protocol (TCP) sequence numbers.

17. The non-transitory computer-readable storage medium of claim 13, wherein the reply comprises at least one packet for which a packet header contains the sequence number.