GLOBAL SERVER LOAD BALANCING

• US 20100011126A1
• Filed: 07/01/2009
• Published: 01/14/2010
• Est. Priority Date: 09/26/2000
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Foundry Networks Incorporated (Broadcom, Inc.)
• Inventors: Cheung, David Chun-Ying, Jalan, Rajkumar Ramniranjan, Hsu, Ivy Pei-Shan
• Granted Patent: US 8,504,721 B2
• Time in Patent Office: Days
• US Class Current: 709/249
• 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 67/1012 based on compliance of requirements or conditions with available server resources
• CPC Class Codes: H04L 67/1021 based on client or server locations

Abstract

A global server load balancing (GSLB) switch serves as a proxy to an authoritative DNS communicates with numerous site switches which are coupled to host servers serving specific applications. The GSLB switch receives from site switches operational information regarding host servers within the site switches neighborhood. When a client program requests a resolution of a host name, the GSLB switch, acting as a proxy of an authoritative DNS, returns one or more ordered IP addresses for the host name. The IP addresses are ordered using metrics that include the information collected from the site switches. In one instance, the GSLB switch places the address that is deemed “best” at the top of the list.

Claims

1. A method of performing load balancing using a load balancing switch, the method comprising:

receiving, at the load balancing switch, performance metrics from a plurality of site switches, each site switch associated with one or more host servers, wherein the one or more host servers associated with a site switch are reachable via the site switch using a virtual address configured at the site switch and wherein the performance metrics received from a site switch comprise one or more metrics related to one or more host servers associated with the site switch;

receiving, at the load balancing server, a plurality of network address from an authoritative domain name server in response to a domain name query;

ordering, at the load balancing server, the plurality of network addresses based upon the performance metrics received from the plurality of site switches to generate an ordered list of network addresses; and

providing the ordered list of network addresses as a response to the domain name query.

2. The method of claim 1 wherein the ordering comprises:

performing a health check for a set of network address included in the plurality of network addresses;

determining at least one network address from the plurality of network addresses that fails the health check; and

excluding the at least one network address from the ordered list of network addresses.

3. The method of claim 2 wherein the health check is a Open System Interconnection (OSI) layer 4 or layer 7 health check.

4. The method of claim 2 wherein the health check is a Transmission Control Protocol (TCP) or User Datagram Protocol (UDP) health check.

5. The method of claim 1 wherein the ordering comprises:

ordering the plurality of network addresses at the load balancing server based upon a first set of performance metrics from the performance metrics received from the plurality of site switches to generate a first ordered list of network addresses;

determining if a single network address tops the first ordered list generated based upon the first set of performance metrics; and

upon determining that a single network address does not top the first ordered list, reordering, at the load balancing server, one or more network addresses from the plurality of network addresses based upon a second set of performance metrics from the performance metrics received from the plurality of site switches, wherein the second set of performance metrics is different from the first set of performance metrics.

6. The method of claim 1 wherein the ordering comprises ordering the plurality of network addresses based upon, for each site switch in the plurality of site switches, a number of sessions supported by the site switch and a maximum number of sessions supportable by the site switch.

7. The method of claim 1 further comprising:

storing, at the load balancing switch, a database storing round trip time information for each site switch in the plurality of site switches, wherein the round trip time information for a site switch is indicative of time for exchanging messages between the site switch and a client machine sending the domain name query; and

updating the database based upon the performance metrics.

8. The method of claim 1 wherein:

the performance metrics comprises round trip time information for each site switch in the plurality of site switches and a client machine sending the domain name query, wherein the round trip time information for a site switch is indicative of time for exchanging messages between the site switch and the client machine; and

the ordering comprises ordering the plurality of network addresses at the load balancing server based upon the round trip time information included in the performance metrics.

9. The method of claim 1 wherein the ordering comprises ordering the plurality of network addresses based upon available session capacity associated with network addresses in the plurality of network addresses.

10. The method of claim 1 wherein the ordering comprises ordering the plurality of network addresses at the load balancing server based upon a flashback speed associated with each site switch in the plurality of site switches, wherein a flashback speed for a site switch is indicative of a time required for the site switch to respond to a health check performed by the load balancing server on the site switch.

11. The method of claim 1 wherein the ordering comprises ordering the plurality of network addresses based upon geographical locations of the host servers associated with the plurality of site switches.

12. The method of claim 1 wherein the ordering comprises placing a network address from the plurality of network addresses of a least recently selected host server for placement at a higher position in the ordered list.

13. A method performed by a load balancing switch, the method comprising:

receiving, at the load balancing switch, performance metrics from a first site switch and a second site switch, wherein the performance metrics received from the first site switch comprise metrics related to one or more host servers associated with the first site switch and reachable via the first site switch and the performance metrics received from the second site switch comprise metrics related to one or more host servers associated with the second site switch and reachable via the second site switch;

receiving, at the load balancing server, a plurality of network address from an authoritative domain name server, the plurality of network addresses generated by the authoritative domain name system server in response to a domain name query;

ordering, at the load balancing server, the plurality of network addresses one or more times based upon the performance metrics received from the first site switch and the second site switch until an ordered list of network addresses is generated that has only one network address at the top of the ordered list; and

providing the ordered list of network addresses as a response to the domain name query.

14. The method of claim 13 wherein the ordering comprises ordering the plurality of network addresses using at least one of

round trip time information associated with the first and second site switches, wherein the round trip time information associated with a site switch is indicative of time for exchanging messages between the site switch and a client machine generating the domain name query,

available session capacity associated with network addresses in the plurality of network addresses,

a flashback speed associated with the first site switch and the second site switch, wherein a flashback speed associated with a site switch is indicative of a time required for the site switch to respond to a health check performed by the load balancing server on the site switch,

geographical locations of the host servers associated with the first and second site switches, and

previous selections of network addresses in the plurality of network address as the best network address in response to a domain name query.

15. A system for performing load balancing, the system comprising:

an authoritative domain name system server; and

a load balancing server coupled to the authoritative domain name system server and to a plurality of site switches, each site switch associated with one or more host servers, wherein the one or more host servers associated with a site switch are reachable via the site switch using a virtual address configured at the site switch;

wherein the load balancing server is configured to;

receive performance metrics from the plurality of site switches, wherein the performance metrics received from a site switch comprise one or more metrics related to the one or more host servers associated with the site switch;

receive a plurality of network address from the authoritative domain name server in response to a domain name query;

order the plurality of network addresses based upon the performance metrics received from the plurality of site switches to generate an ordered list of network addresses; and

provide the ordered list of network addresses as a response to the domain name query.

16. The system of claim 15 wherein the load balancing server is configured to:

perform a health check for a set of network address included in the plurality of network addresses;

determine at least one network address from the plurality of network addresses that fails the health check; and

exclude the at least one network address from the ordered list of network addresses.

17. The system of claim 16 wherein the health check is a Open System Interconnection (OSI) layer 4 or layer 7 health check.

18. The system of claim 16 wherein the health check is a Transmission Control Protocol (TCP) or User Datagram Protocol (UDP) health check.

19. The system of claim 15 wherein the load balancing server is configured to:

order the plurality of network addresses based upon a first set of performance metrics from the performance metrics received from the plurality of site switches to generate a first ordered list of network addresses;

determine if a single network address tops the first ordered list generated based upon the first set of performance metrics; and

upon determining that a single network address does not top the first ordered list, reordering one or more network addresses from the plurality of network addresses based upon a second set of performance metrics from the performance metrics received from the plurality of site switches, wherein the second set of performance metrics is different from the first set of performance metrics.

20. The system of claim 15 wherein the load balancing switch is configured to order the plurality of network addresses based upon, for each site switch in the plurality of site switches, a number of sessions supported by the site switch and a maximum number of sessions supportable by the site switch.