Method and system for balancing load distribution on a wide area network

• US 7,441,045 B2
• Filed: 02/16/2001
• Issued: 10/21/2008
• Est. Priority Date: 12/13/1999
• Status: Expired due to Term

• Current Assignee: F5 Networks, Inc. (F5 Incorporated)
• Original Assignee: F5 Networks, Inc. (F5 Incorporated)
• Inventors: Skene, Bryan D., Tennican, Scott P., Kee, Thomas E.
• Primary Examiner(s): Follansbee; John
• Assistant Examiner(s): Shingles; Kristie D
• Application Number:
  US09/788,281
• Publication Number:
  US 20010052016A1
• Time in Patent Office: 2,804 Days
• Field of Search: 709/200, 709/223, 709/229, 709/228, 709/241, 709/201, 712/27, 370/400
• US Class Current: 709/241
• CPC Class Codes: G06F 9/505 considering the load
• CPC Class Codes: H04L 45/00 Routing or path finding of packets in data switching networks routing or path finding in wireless networks H04W40/00
• CPC Class Codes: H04L 45/586 of virtual routers
• CPC Class Codes: H04L 61/4511 using domain name system [DNS]
• 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 67/1012 based on compliance of requirements or conditions with available server resources
• CPC Class Codes: H04L 67/1017 based on a round robin mechanism
• CPC Class Codes: H04L 67/1019 Random or heuristic server selection
• CPC Class Codes: H04L 67/1029 using data related to the state of servers by a load balancer
• CPC Class Codes: H04L 67/1038 Load balancing arrangements to avoid a single path through a load balancer

Abstract

A system and method for balancing the load on virtual servers managed by server array controllers at separate data centers that are geographically distributed on a wide area network such as the Internet is described. The virtual servers provide access to resources associated with a domain name request by a client program. When a Primary Domain Name System (DNS) determined the requested domain name is delegated to a EDNS, the EDNS employs metric information and statistics to resolve an IP address for a virtual server that is selected by the EDNS to optimally balance the load and provide access to resources associated with the domain name. The EDNS may load balance name servers. Additionally, the name server load balancing system may bridge disparate content delivery networks. Internet addresses are divided into geographical information that is used to delegate traffic. Also, metric information is collected and analyzed to help distribute the traffic.

Claims

1. A method of delivering content across a plurality of zones within a network, comprising:

receiving a request from a client located within one of the plurality of zones for access to resources associated with a domain name;

determining network conditions for the network based on a determination of the load for each of the plurality of zones;

distributing the request to one of the plurality of zones based on the determined network conditions;

selecting one of a plurality of servers within the zone in which the request was distributed, the selection of the server being based on a determination for optimally balancing the load across the plurality of servers;

resolving an Internet protocol (IP) address of the selected server; and

determining whether to delegate delivery of the resources to a content delivery network based on the determination for optimally balancing the load across the plurality of servers, a Time to Live value set at a pool level for each of a plurality of available pools, and a pool load-balancing setting;

wherein selecting one of the plurality of servers further comprises;

marking each of a plurality of pools to a not tried state, determining the pool load-balancing setting, selecting one of the plurality of pools that is marked to an initialization state, marking the selected one of the plurality of pools to a tried state, attempting to obtain an answer using the determined pool load-balancing on the selected one of the plurality of pools, and determining if the answer was obtained.

2. The method of claim 1, further comprising querying a local Domain Name System (DNS) to provide the IP address associated with the domain name.

3. The method of claim 2 wherein when the IP address is not present at the local DNS, querying a primary DNS to resolve the IP address associated with the domain name.

4. The method of claim 3, wherein when the primary DNS determines the domain name is delegated to a EDNS, further comprises referring the local DNS to the EDNS to resolve the IP address for the selected server, the EDNS employs at least one of a plurality of load balancing determinations to select one of the plurality of servers and resolve the IP address for the selected server.

5. The method of claim 4 wherein selecting one of the plurality of servers, further comprises accounting for computing power behind a wide area virtual server.

6. The method of claim 1, further comprising:

deriving cost metrics for network paths in topological maps;

using the cost metrics to determine a geographic location of the request; and

distributing the request based on the geographic location.

7. The method of claim 1, further comprising:

using a last hop address to determine a geographic location of the request; and

distributing the request based on the geographic location.

8. The method of claim 1, further comprising using a last-resort pool to select the server.

9. The method of claim 1, wherein at least a portion of the plurality of servers are virtual servers.

10. The method of claim 9 wherein selecting one of the plurality of servers within the zone in which the request was distributed, the selection of the server being based on a determination for optimally balancing the load across the plurality of servers, further comprising:

determining if the selected server is a virtual server, and if so;

determining a number of nodes up on the virtual server;

determining if the number of nodes up or the number of connections for the virtual server exceeds a predetermined number and if so returning a value indicating the capacity of the virtual server has been exceeded.

11. A system for balancing the load on a plurality of virtual servers that provide access to resources associated with a domain name, comprising:

a memory for storing logical instructions; and

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

receiving a request from a client located within one of the plurality of zones for access to resources associated with a domain name through an authoritative server;

determining network conditions for the network based on a determination of the load for each of the plurality of zones;

distributing the request to one of the plurality of zones based on the determined network conditions;

selecting one of the plurality of servers within the zone in which the request was distributed, the selection of the server being based on a determination for optimally balancing the load across the plurality of servers;

resolving an Internet protocol (IP) address of the selected server; and

determining whether to delegate delivery of the resources to a content delivery network based on the determination for optimally balancing the load, wherein the determination of whether to delegate delivery is made prior to a connection of the client to the content delivery network if the delivery of resources is delegated to a delegation pool associated with the content delivery network;

wherein selecting one of the plurality of servers further comprises;

marking each of a plurality of pools to a not tried state, determining the pool load-balancing setting, selecting one of the plurality of pools that is marked to an initialization state, marking the selected one of the plurality of pools to a tried state, attempting to obtain an answer using the determined pool load-balancing on the selected one of the plurality of pools, and determining if the answer was obtained.

12. The system of claim 11, wherein selecting one of the plurality of servers, further comprises choosing the server based on one of a plurality of static load balancing determinations for each server, the plurality of static load balancing determinations being selectable and including random, round robin, static ratio, global availability and topology.

13. The system of claim 11 wherein selecting one of the plurality of servers, further comprises choosing the server based on one of a plurality of dynamic load balancing determinations for each server, the dynamic load balancing determinations being selectable and including completion rate, least connections, packet rate, hops, round trip times, new connection rate, kilobyte rate, quality of service and dynamic ratio.

14. The system of claim 11 wherein selecting one of the plurality of servers, further comprises accounting for computing power behind a wide area virtual server.

15. The system of claim 11, further comprising distributing the request to a closest server based on a closest identified geographic CONTENT-SERVER or a best-performing CONTENT-SERVER, or a best quality path.

16. The system of claim 11, further comprising:

deriving cost metrics for network paths in topological maps;

using the cost metrics to determine a geographic location of the request; and

distributing the request based on the geographic location.

17. The system of claim 11, further comprising:

using a last hop address to determine a geographic location of the request; and

distributing the request based on the geographic location.

18. The system of claim 11, further comprising using a last-resort pool to select the server.

19. The system of claim 11 wherein at least a portion of the plurality of servers are virtual servers.

20. The system of claim 19 wherein selecting one of the plurality of servers within the zone in which the request was distributed, the selection of the server being based on a determination for optimally balancing the load across the plurality of servers further comprising:

determining if the selected server is a virtual server, and if so;

determining a number of nodes up on the virtual server;

determining if the number of nodes up or the number of connections for the virtual server exceeds a predetermined number and if so returning a value indicating the capacity of the virtual server has been exceeded.

21. A system for delivering content across a plurality of zones within a network, comprising:

a processor that includes;

a receiver that receives a request from a client located within one of the plurality of zones to access resources associated with a domain name;

a means for distributing the request to one of the plurality of zones based on network conditions of the plurality of zones;

a load balancer that selects one of a plurality of servers within the zone in which the request is distributed;

a system component that resolves an Internet protocol (IP) address of the selected server;

a means for determining whether to delegate delivery of the resources to a content delivery network based on a load balancing determination for optimally balancing the load across the plurality of servers or the content delivery network, wherein the plurality of servers and the content delivery network are designated members of different delegation pools of content sources; and

a means for selecting one of the plurality of servers comprising marking each of a plurality of pools to a not tried state, determining the pool load-balancing setting, selecting one of the plurality of pools that is marked to an initialization state, marking the selected one of the plurality of pools to a tried state, attempting to obtain an answer using the determined pool load-balancing on the selected one of the plurality of pools, and determining if the answer was obtained.

22. A method for delivering content over a network, comprising:

receiving a request from a client for access to resources associated with a domain name;

distributing the request to one of a plurality of zones based at least in part on network conditions associated with the zones, wherein distributing the request includes determining whether to delegate delivery of the resources to a content delivery network;

selecting one of a plurality of servers within the zone in which the request is distributed, wherein selecting the server is based at least in part on a balancing of the load among the servers;

resolving the domain name into an Internet protocol (IP) address of the selected server; and

determining whether to delegate, in a controlled manner, delivery of the resources to a content delivery network or to an origin site based on the balancing of the load and a mapping created between pools of content sources and an identified physical geographic location of an IP address of the request;

wherein selecting one of the plurality of servers further comprises;

marking each of a plurality of pools to a not tried state, determining the pool load-balancing setting, selecting one of the plurality of pools that is marked to an initialization state, marking the selected one of the plurality of pools to a tried state, attempting to obtain an answer using the determined pool load-balancing on the selected one of the plurality of pools, and determining if the answer was obtained.