Method and system for enabling persistent access to virtual servers by an LDNS server

• US 7,047,301 B2
• Filed: 01/31/2001
• Issued: 05/16/2006
• Est. Priority Date: 01/31/2000
• Status: Active Grant

• Current Assignee: F5 Networks, Inc. (F5 Incorporated)
• Original Assignee: F5 Networks, Inc. (F5 Incorporated)
• Inventors: Skene, Bryan D., Thornewell, Peter M.
• Primary Examiner(s): Wiley, David
• Assistant Examiner(s): BOUTAH, ALINA A
• Application Number:
  US09/773,427
• Publication Number:
  US 20010047415A1
• Time in Patent Office: 1,931 Days
• Field of Search: 709/203, 709/228, 709223-226
• US Class Current: 709/226
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/10015 Access to distributed or replicated servers, e.g. using brokers
• 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 67/1027 Persistence of sessions during load balancing
• CPC Class Codes: H04L 67/14 Session management for real-time applications in data packet communications networks H04L65/1066
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

Disclosed are methods and systems for providing persistence across multiple requests in a WAN load-balanced environment. More than one load balancing system may be used to provide persistence while load balancing. One method and system disclosed provides persistence by using modulus arithmetic to load balance requests. Another method and system disclosed provides persistence using topology information contained in the request. Another method and system disclosed provides persistence by storing connection information to refer a timely continuation request of a prior request to the same server the prior request was referred to. When more than one load balancing system is used with this method, the load balancing systems periodically exchange the stored connection information so that each load balancing system may provide persistence to repeat requests.

Claims

1. A method for enabling a client to access a resource on a wide area network environment, comprising:

(a) receiving a request for the resource from a connection that is associated with the client;

(b) selecting a method for load balancing each request from the connection, wherein the selected load balancing method employs modulus arithmetic to select a virtual server managed by a selected server array controller, including;

converting a LDNS server'"'"'s IP address into a first value;

dividing the first value by the total amount (N) of virtual servers that are available, each available virtual server corresponding to a particular value of N;

adding one to a remainder of the dividing action to create a second value; and

selecting the virtual server that corresponds to the particular value of N that is one greater than the second value;

(c) employing the selected method to select one of a plurality of server array controllers to handle each request from the connection to the resource; and

(d) persistently referring each request associated with the connection to the selected server array controller until another method is selected for load balancing each request from the connection, wherein the selected server array controller associates the client'"'"'s connection with the requested resource.

2. The method of claim 1, wherein a requestor is a local domain name system (LDNS) server.

3. The method of claim 1, further comprising when the selected virtual server is determined to be down, the selected load balancing method performs further actions, including:

(a) marking the down selected virtual server as unavailable;

(b) decrementing the total amount of available virtual servers by 1 to create a new value for N; and

(c) employing the new value for N to select another virtual server array.

4. The method of claim 1, wherein a requestor communicates with a client through a web proxy.

5. The method of claim 1, wherein the selected server array controller associates a requestor with a virtual server that includes the resource, wherein the virtual server is managed by the selected server array controller.

6. The method of claim 1, further comprising storing information associated with the request.

7. The method of claim 6, wherein the information includes an IP address associated with a requester, another IP address associated with the selected server array controller, and a time value for controlling how long information is valid.

8. The method of claim 1, wherein each subsequent request is made by any one of a plurality of LDNS servers.

9. The method of claim 1, wherein the selected server array controller manages at least one virtual server that provides access to the resource.

10. A computer readable medium that stores executable data for enabling actions for a client to access a resource on a wide area network enviroment, the actions comprising:

(a) a first component receiving a request for the resource from a connection that is associated with the client;

(b) a second component selecting a method for load balancing each request from the connection, wherein the selected load balancing method employs modulus arithmetic to select a virtual server managed by the selected server array controller based on actions, including;

(i) converting a LDNS server'"'"'s IP address into a first value;

(ii) dividing the first value by the total amount (N) of virtual servers that are available, each available virtual server corresponding to a particular value of N;

(iii) adding one to a remainder of the dividing action to create a second value; and

(iv) selecting the virtual server that corresponds to the particular value of N that is one greater than the second value;

(c) a third component employing the selected method to select one of a plurality of server array controllers to handle each request from the connection to the resource; and

(d) a fourth component persistently referring each request associated with the connection to the selected server array controller until another method is selected for load balancing each request from the connection, wherein the selected server array controller associates the client'"'"'s connection with the requested resource.

11. A system for performing actions for a client to access a resource on a wide area network environment, comprising:

(a) a first component for receiving a request for the resource from a connection that is associated with the client;

(b) a second component for selecting a method for load balancing each request from the connection, wherein the selected load balancing method employs modulus arithmetic to select a virtual server managed by a selected server array controller, including;

(i) converting a LDNS server'"'"'s IP address into a first value;

(ii) dividing the first value by the total amount (N) of virtual servers that are available, each available virtual server corresponding to a particular value of N;

(iii) adding one to a remainder of the dividing action to create a second value; and

(iv) selecting the virtual server that corresponds to the particular value of N that is one greater than the second value;

(c) a third component for employing the selected method to select one of a plurality of server array controllers to handle each request from the connection to the resource; and

(d) a fourth component for persistently referring each request associated with the connection to a selected server array controller until another method is selected for load balancing each request from the connection, wherein the selected server array controller associates the client'"'"'s connection with the requested resource.