Method and system for storing load balancing information with an HTTP cookie

• US 20020040400A1
• Filed: 12/04/2001
• Published: 04/04/2002
• Est. Priority Date: 07/15/1999
• Status: Active Grant

• Current Assignee: F5 Networks, Inc. (F5 Incorporated)
• Original Assignee: F5 Networks, Inc. (F5 Incorporated)
• Inventors: Masters, Richard R.
• Granted Patent: US 6,473,802 B2
• Time in Patent Office: Days
• US Class Current: 709/228
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/1008 based on parameters of servers, e.g. available memory or workload monitoring of computer activity G06F11/30
• CPC Class Codes: H04L 67/101 based on network conditions
• CPC Class Codes: H04L 67/1017 based on a round robin mechanism
• CPC Class Codes: H04L 67/1023 based on a hash applied to IP addresses or costs
• CPC Class Codes: H04L 67/1027 Persistence of sessions during load balancing

Abstract

A method and system for inserting and examining Cookies in the data streams of HTTP connections for the purpose of persistently directing HTTP connections to the same destination. The invention enables a network device to direct subsequent HTTP connections from the same client to the same server (destination) for accessing the requested resources. There are four modes for employing the Cookie to persistently direct HTTP connections. The associative mode inserts a Cookie that uniquely identifies the client into an HTTP response. The passive mode inserts Cookie information that uniquely identifies a previously selected destination into an HTTP response. In the rewrite mode, a network device manages the destination information that is rewritten over blank Cookie information generated by the destination producing the HTTP response. The insert mode inserts and removes Cookie information in the data packets for HTTP requests and responses prior to processing by the destination.

Claims

1. Method for load balancing access to a resource identified in a hyper text transport protocol (HTTP) request, comprising:

(a) examining an HTTP request to determine when a Cookie is included with the HTTP request, the Cookie including information that indicates a destination for accessing the resource identified in the HTTP request;

(b) when the Cookie is included in the HTTP request, sending the HTTP request to the destination that is indicated by the Cookie'"'"'s information;

(c) generating an HTTP response at the destination, the HTTP response providing access to the requested resource;

(d) inserting a copy of the information in the Cookie into the HTTP response; and

(e) sending the HTTP response with the copy of the information in the Cookie to the sender of the HTTP request, so that a subsequent HTTP request to access the resource will include another Cookie with information indicating that the resource is accessible at the destination.

2. The method of claim 1, further comprising:

(a) sending the HTTP request to a server array controller that manages a plurality of node servers; and

(b) employing the server array controller to select one of the plurality of node servers to receive the HTTP request based on the information in the Cookie, the selected node server being associated with the destination.

3. The method of claim 2, wherein the selected node server generates the HTTP response.

4. The method of claim 3, further comprising including an identifier with the copy of the information in the Cookie, the identifier associating the selected node server with the destination.

5. The method of claim 4, further comprising encoding the identifier.

6. The method of claim 5, further comprising employing a mathematical product to encode the identifier.

7. The method of claim 6, wherein the mathematical product includes a hash value.

8. The method of claim 4, further comprising generating a time stamp that is included in the HTTP response.

9. The method of claim 4, further comprising:

(a) employing the server array controller to insert the copy of the information in the Cookie into the HTTP response; and

(b) employing the server array controller to rewrite a data packet that includes the HTTP response and the copy of the information in the Cookie.

10. The method of claim 4, wherein the selected node sever generates the HTTP response and includes a blank identifier in the copy of the information in the Cookie.

11. The method of claim 10, further comprising employing the server array controller to write the identifier over the blank identifier in the copy of the information in the Cookie.

12. The method of claim 4, further comprising employing the selected node server to include the copy of the information in the Cookie with the generated HTTP response.

13. The method of claim 8, wherein the selected node server generates the time stamp that is included in the HTTP response.

14. The method of claim 8, wherein the server array controller generates the time stamp that is included in the HTTP response.

15. The method of claim 2, further comprising:

(a) when the Cookie is not included in the HTTP request, employing the server array controller to select one of the plurality of node servers to receive the HTTP request and generate the HTTP response providing access to the requested resource; and

(b) sending the HTTP response from the selected node server to the sender of the HTTP request, the HTTP response including information for creating another Cookie at the sender, so that a subsequent HTTP request to access the resource will include the other Cookie with information indicating that the selected node server is the destination for accessing the requested resource.

16. The method of claim 15, further comprising employing the server array controller to balance the load demand on the plurality of node servers by determining an optimal node server to receive the HTTP request and generate the HTTP response.

17. The method of claim 16, wherein the server array controller employs at least one of a plurality of functions to determine the optimal node server to balance the load demand on the plurality of node servers, the plurality of functions including round trip time, round robin, least connections, packet completion rate, quality of service, server array controller packet rate, topology, global availability, hops, static ratio and dynamic ratio.

18. The method of claim 2, further comprising:

(a) until the HTTP request is provided to the server array controller, employing the server array controller to buffer communication between the sender and the destination; and

(b) when the HTTP request is provided to the server array controller, replaying in consecutive order the buffered communication to at least one of the plurality of node servers that is associated with the destination.

19. The method of claim 1, further comprising including a plurality of Cookies in the HTTP request, each Cookie having a different type.

20. The method of claim 19, further comprising determining a type for each Cookie, the type of each Cookie indicating how the information included in each Cookie is to be utilized.

21. The method of claim 1, wherein the sender includes at least one of a client, server and host machine.

22. The method of claim 1, wherein the destination includes at least one of a host machine, server array controller, router, node server, firewall and client.

24. The method of claim 23, further comprising a server array controller that manages a plurality of node servers, wherein the server array controller compares the information identifying the sender to the destination that is associated with the identified sender in the table, the destination being one of the node servers managed by the server array controller.

25. The method of claim 24, further comprising employing the server array controller to insert the copy of the information in the Cookie into the HTTP response.

26. The method of claim 24, further comprising:

(a) employing the node server to insert blank information into the HTTP response; and

(b) employing the server array controller to rewrite the blank information to include the copy of the information in the Cookie, the server array controller sending the HTTP response with the copy of the information in the Cookie to the sender identified in the HTTP request.

30. The method of claim 29, further comprising when the HTTP request is determined to be without the Cookie, selecting one of a plurality of destination servers and sending the HTTP request to the selected destination server.

31. The method of claim 30, further comprising in the HTTP response from the selected destination server, including a new Cookie with information to identify the selected destination server.

32. The method of claim 30, further comprising:

(a) adding a new Cookie to the HTTP request forwarded to the selected destination server; and

(b) rewriting the new Cookie with new information identifying the selected destination server and including the rewritten new Cookie in the HTTP response from the selected destination serve

23. Method for load balancing access to a resource identified in a hyper text transport protocol (HTTP) request, comprising:

(a) examining an HTTP request to determine when a Cookie is included with the HTTP request, the Cookie including information that identifies a sender of the HTTP request;

(b) when the Cookie is included in the HTTP request, comparing the information identifying the sender to a table of at least one destination, the HTTP request being sent to a destination that is associated with the identified sender in the table;

(c) generating an HTTP response at the destination, the HTTP response providing access to the requested resource;

(d) inserting a copy of the information in the Cookie into the HTTP response; and

(e) sending the HTTP response with the copy of the information in the Cookie to the identified sender of the HTTP request, so thatthat a subsequent HTTP request to access the resource from the identified sender will include another Cookie with information that identifies the sender of the subsequent HTTP request.

27. A system for load balancing access to a resource indicated in a hyper text transport protocol (HTTP) request, comprising:

(a) a memory for storing logical instructions; and

(b) a processor for executing the logical instructions stored in the memory, the execution of the logical instructions causing functions to be performed including;

(i) examining an HTTP request to determine when a Cookie is included with the HTTP request, the Cookie including information that indicates a destination for accessing the resource identified in the HTTP request;

(ii) when the Cookie is included in the HTTP request, sending the HTTP request to the destination that is indicated by the Cookie'"'"'s information;

(iii) generating an HTTP response at the destination, the HTTP response providing access to the requested resource;

(iv) inserting a copy of the information in the Cookie into the HTTP response; and

(v) sending the HTTP response with the copy of the information in the Cookie to the sender of the HTTP request, so that a subsequent HTTP request to access the resource will include another Cookie with information indicating that the resource is accessible at the destination.

28. A system for load balancing access to a resource indicated in a hyper text transport protocol (HTTP) request, comprising:

(a) a memory for storing logical instructions; and

(b) a processor for executing the logical instructions stored in the memory, the execution of the logical instructions causing functions to be performed, including;

(i) examining an HTTP request to determine when a Cookie is included with the HTTP request, the Cookie including information that identifies a sender of the HTTP request;

(ii) when the Cookie is included in the HTTP request, comparing the information identifying the sender to a table of at least one destination, the HTTP request being sent to a destination that is associated with the identified sender in the table;

(iii) generating an HTTP response at the destination, the HTTP response providing access to the requested resource;

(iv) inserting a copy of the information in the Cookie into the HTTP response; and

(v) sending the HTTP response with the copy of the information in the Cookie to the identified sender of the HTTP request, so that a subsequent HTTP request to access the resource from the identified sender will include another Cookie with information that identifies the sender of the subsequent HTTP request.

29. A method for load balancing access to a resource identified in a hyper text transport protocol (HTTP) request, comprising:

(a) receiving an HTTP request at a server array controller from a sender;

(b) employing the server array controller to examine the HTTP request to determine when a Cookie is included with the HTTP request, wherein the Cookie includes information that indicates a destination server for accessing the resource identified in the HTTP request;

(c) sending the HTTP request to the destination server indicated by the Cookie'"'"'s information;

(d) at the destination server, generating an HTTP response that provides access to the requested resource and includes a copy of the information in the Cookie; and

(e) sending the HTTP response to the sender of the HTTP request, so that a subsequent HTTP request from the sender to access the resource will include another Cookie with information indicating that the resource is accessible at the destination server.