Server load balancing method and system

• US 7,099,915 B1
• Filed: 06/30/2000
• Issued: 08/29/2006
• Est. Priority Date: 06/30/2000
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Jordan, James, Kersey, Edward, Bacchus, Shaheed, Tenereillo, Peter, Howes, Richard
• Primary Examiner(s): Meky, Moustafa M.
• Application Number:
  US09/608,789
• Time in Patent Office: 2,251 Days
• Field of Search: 709200-203, 709217-227
• US Class Current: 709/203
• CPC Class Codes: H04L 67/02 based on web technology, e.g. hypertext transfer protocol [HTTP]
• 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 67/1017 based on a round robin mechanism
• CPC Class Codes: H04L 67/1027 Persistence of sessions during load balancing

Abstract

A method and system for providing a connection between a client and a server with load balancing between servers are disclosed. A computer-implemented method of the present invention generally includes binding a primary virtual server to a set of URLs, each URL having an associated real server and receiving a request from a client for connection to the primary virtual server. One of the real servers are selected for connection with the client and a redirect message is sent to the client specifying the URL associated with the selected real server. The method further includes receiving a new connection request from the client for connection with the selected real server.

Claims

1. A computer-implemented method for providing a persistent connection between a client and a server, the method comprising:

binding a primary virtual server to a set of URLs, each URL having an associated real server;

receiving a request from a client for connection to the primary virtual server;

selecting one of the real servers for connection with the client;

sending a redirect message to the client specifying the selected real server; and

receiving a new connection request from the client for connection with the selected real server;

wherein the client is connected to the selected real server for the duration of a transaction.

2. The method of claim 1 further comprising binding each of the real servers to a virtual server, each pair of real and virtual servers having the same IP address.

3. The method of claim 2 wherein the IP address is associated with the URL of the corresponding real server.

4. The method of claim 2 wherein each pair of real and virtual servers share weight assignments.

5. The method of claim 2 wherein each pair of real and virtual servers share state information.

6. The method of claim 1 wherein the client request is an HTTP request.

7. The method of claim 6 wherein the redirect is an HTTP redirect.

8. The method of claim 7 wherein the HTTP redirect comprises a URL of the selected real server.

9. The method of claim 1 wherein selecting one of the real servers comprises load balancing the real servers.

10. The method of claim 9 wherein load balancing is only performed in selecting one of the real servers for connection with the client.

11. The method of claim 1 further comprising providing a backup link for each of the real servers to the primary virtual server.

12. The method of claim 1 further comprising providing a backup link for each of the real servers to one of the other real servers.

13. The method of claim 1 further comprising binding an additional real server to the primary virtual server and load sharing between the new real server and the original set of real servers.

14. The method of claim 1 wherein receiving a request from a client comprises receiving a request at a local director.

15. The method of claim 1 further comprising forwarding messages from the client to a backup server associated with the selected real server for the duration of the transaction.

16. The method of claim 2 wherein a directed IP identifier provides one-to-one bindings between the virtual server and real server pairs.

17. The method of claim 16 further comprising linking said directed IP identifier to a URL.

18. The method of claim 16 further comprising a URL associated with the virtual server inheriting weights and states assigned to the directed IP identifier.

19. The method of claim 1 further comprising creating secondary virtual servers, each of said secondary virtual servers bound to one of the real servers.

20. The method of claim 1 further comprising:

receiving a request from the client during the transaction for connection to an SSL page; and

creating a link between the selected real server and the SSL page.

21. A computer-implemented method for load balancing between servers and providing a persistent connection between a client and a server, comprising:

receiving a request from a client for connection to a primary virtual server to start a session, the primary virtual server being bound to a plurality of secondary virtual servers each associated with a real server and having the same address as the real server;

selecting one of the real servers for connection with the client;

sending a redirect message to the client specifying the selected real server;

receiving a new request from the client for connection to the selected real server;

forwarding to the selected real server transmission originating from the client;

forwarding to the client transmission originating from the selected real server; and

continuing to forward transmission from the client to the selected server throughout the session.

22. The method of claim 21 wherein receiving a request from the client comprises receiving an HTTP request and forwarding to the selected real server transmission comprises forwarding an HTTP request.

23. The method of claim 22 further comprising sending an HTTP redirect message to the client, the HTTP redirect message identifying the selected real server.

24. A computer program product for providing a persistent connection between a client and a server, the product comprising:

code that binds a primary virtual server to a set of URLs, each URL having an associated real server;

code that receives a request from a client for connection to the primary virtual server;

code that selects one of the real servers for connection with the client;

code that sends a redirect message to the client specifying the selected real server;

code that receives a new request from the client for connection to the selected real server, wherein the client is connected to the selected real server for the duration of a transaction; and

a computer-readable storage medium for storing the codes.

25. The computer program product of claim 24 wherein the computer readable medium is selected from the group consisting of CD-ROM, floppy disk, tape, flash memory, system memory, hard drive, and data signal embodied in a carrier wave.

26. The computer program product of claim 24 further comprising code that binds each of the real servers to a virtual server, each pair of real and virtual servers having the same IP address.

27. The computer program product of claim 24 further comprising code that provides a backup server for each of the real servers.

28. A computer program product for binding a plurality of real servers to a primary virtual server for establishing persistent connections between a client and the real servers, the product comprising:

code that creates an identifier for each of the real servers;

code that binds the real servers to the primary virtual server;

code that creates a plurality of secondary virtual servers, each of the secondary virtual servers associated with one of the real servers and having the same address as the associated real server;

code that binds each of the secondary virtual servers with its associated real server;

code that maintains a persistent connection between a client and one of the real servers throughout a transaction; and

a computer-readable storage medium for storing the codes.

29. The computer program product of claim 28 wherein the real server identifiers are URLs.

30. The computer program product of claim 29 wherein the primary virtual server is bound to the URLs of the real servers.

31. The computer program product of claim 28 further comprising code that load balances the real servers.

32. The computer program product of claim 31 wherein load balancing is performed only to connect a client with one of the real servers at the start of a transaction.

34. The system of claim 31 further comprising a plurality of secondary virtual servers, each of said plurality of secondary virtual servers associated with one of said plurality of real servers.

35. The system of claim 34 wherein each pair of secondary virtual servers and real servers have the same IP address.

36. The system of claim 34 further comprising a local director comprising said processor and secondary virtual servers and configured to balance loads between said plurality of real servers.

33. A computer system for providing a persistent connection between a client and a server, the system comprising:

a virtual server;

a plurality of real servers each having an associated URL; and

a processor for binding the virtual server to the URLs of the real servers, selecting one of the real servers for connection to a client, redirecting a connection request for the virtual server from the client to the selected real server, the processor configured for creating a persistent connection between the selected real server and the client throughout a session.

37. A system for directing flow between a client and two or more servers, the system comprising:

a primary virtual server bound to a plurality of URLs, each URL having an associated real server;

means for receiving a client request for content;

means for selecting a real server for providing content to the client;

means for providing the URL of the selected real server to the client; and

means for receiving a new connection request from the client for connection to the selected real server;

wherein the client is connected to the selected real server for the duration of a transaction.

38. A network apparatus for directing flow between a client and two or more servers, the network apparatus comprising:

memory; and

a processor configured to;

bind a primary virtual server to a set of URLs, each URL having an associated real server;

receive a request from a client for connection to the primary virtual server;

select one of the real servers for connection with the client;

receive a new connection request from the client for connection with the selected real server;

send a redirect message to the client specifying the selected real server; and

receive a new connection request from the client for connection with the selected real server;

wherein the client is connected to the selected real server for the duration of a transaction.