Bypassing a load balancer in a return path of network traffic

• US 10,212,071 B2
• Filed: 12/21/2016
• Issued: 02/19/2019
• Est. Priority Date: 12/21/2016
• Status: Active Grant

• Current Assignee: Nicira Incorporated (Broadcom, Inc.)
• Original Assignee: Nicira Incorporated (Broadcom, Inc.)
• Inventors: Kancherla, Mani, Jain, Jayant, Sengupta, Anirban
• Primary Examiner(s): Elpenord, Candal
• Assistant Examiner(s): Jeong, Moo
• Application Number:
  US15/387,572
• Publication Number:
  US 20180176124A1
• Time in Patent Office: 790 Days
• CPC Class Codes: H04L 45/22 Alternate routing
• CPC Class Codes: H04L 45/34 Source routing
• CPC Class Codes: H04L 45/38 Flow based routing
• CPC Class Codes: H04L 47/2483 involving identification of individual flows
• CPC Class Codes: H04L 61/2521 Translation architectures other than single NAT servers
• CPC Class Codes: H04L 67/1004 Server selection for load balancing

Abstract

Some embodiments provide a method that allows a first data compute node (DCN) to forward outgoing traffic to a second DCN directly in spite of receiving the incoming traffic from the second DCN through a load balancer. That is, the return traffic'"'"'s network path from the first DCN to the second DCN bypasses the load balancer, even though a request that initiated the return traffic is received through the load balancer. The method receives a first data message from a load balancer to be sent to a DCN. After identifying a particular address embedded in the data message by the load balancer, the method generates a table entry, based on source and destination addresses of the data message and the identified address. This entry is used for modifying a source address of a subsequent data message received from the DCN in response to the data message.

Claims

1. A method for forwarding load balanced network traffic, the method comprising:

at a host computer executing a data compute node (DCN),

receiving, from a load balancer, a first data message that has (i) a first address associated with the DCN as a destination address and (ii) a source address identifying a source of the first data message;

identifying a second address embedded in the first data message by the load balancer, the second address originally specified as the destination address in a header of the first data message before being replaced with the first address in a load balancing operation of the load balancer;

based on (i) the source address and the first address of the first data message and (ii) the second address embedded in the first data message, generating a table entry to use subsequently to replace, with the second address, the first address that is specified as a source address of a subsequent data message sent by the DCN to the source of the first data message; and

forwarding the first data message towards the DCN.

2. The method of claim 1 further comprising storing the generated table entry with the second address in a local data storage of the host computer.

3. The method of claim 2 further comprising, prior to generating the table entry, determining that no table entry associated with the first data message exists in the local data storage.

4. The method of claim 1, wherein

the DCN is one particular DCN in a group of DCNs that all perform a common operation, and

the first address is an internet protocol (IP) address of the DCN and the second address is a virtual IP address of the group of DCNs.

5. The method of claim 1, wherein the source of the first data message is a client requesting data from a DCN in the group of DCNs.

6. The method of claim 5 further comprising forwarding the second data message towards the client via a path that bypasses the load balancer.

7. The method of claim 1, wherein the table entry identifies a data flow based on the source and destination addresses of the first data message, by assigning the second address of the first data message as a source address of a reverse flow and assigning the source address of the first data message as a destination address of the reverse flow.

8. The method of claim 7 further comprising generating a second table entry for the data flow of the first data message using the source and destination addresses of the first data message.

9. The method of claim 1, wherein identifying the second address comprises retrieving a set of values embedded in a particular header field of the first data message and matching the set of retrieved values to an entry in a mapping table, the entry further mapping the set of retrieved values to the second address.

10. The method of claim 1, wherein the DCN comprises a virtual server of a set of virtual servers that implements a distributed application, wherein the first data message is for requesting data from the distributed application.

11. A non-transitory machine readable medium storing a program which when executed by at a set of processing units of a host computer forwards load balanced network traffic, the processing units of the host computer further executing a data compute node (DCN), the program comprising sets of instructions for:

receiving, from a load balancer, a first data message that has (i) a first address associated with the DCN as a destination address and (ii) a source address identifying a source of the first data message;

identifying a second address embedded in the first data message by the load balancer, the second address originally specified as the destination address in a header of the first data message before being replaced with the first address in a load balancing operation of the load balancer;

based on (i) the source address and the first address of the first data message and (ii) the second address embedded in the first data message, generating a table entry to use subsequently to replace with the second address, the first address that is specified as a source address of a subsequent data message sent by the DCN to the source of the first data message; and

forwarding the first data message towards the DCN.

12. The non-transitory machine readable medium of claim 11, wherein

the DCN is one particular DCN in a group of DCNs that all perform a common operation, and

the first address is an internet protocol (IP) address of the DCN and the second address is a virtual IP address of the group of DCNs.

13. The non-transitory machine readable medium of claim 11, wherein the source of the first data message is a client requesting data from a DCN in the group of DCNs.

14. The non-transitory machine readable medium of claim 13, wherein the program further comprises a set of instructions for forwarding the second data message towards the client via a path that bypasses the load balancer.

15. The non-transitory machine readable medium of claim 11, wherein the DCN is a particular virtual server in a set of virtual servers that implement a distributed application and the first address is a network address of the particular virtual server.

16. The non-transitory machine readable medium of claim 15, wherein the second address is a virtual internet protocol (VIP) address associated with the distributed application.

17. The non-transitory machine readable medium of claim 16, wherein the load balancer selects the particular virtual server over other virtual servers in the set based on a load balancing algorithm.