Method for improving network server load balancing

• US 7,908,355 B2
• Filed: 06/12/2003
• Issued: 03/15/2011
• Est. Priority Date: 06/20/2002
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Chauffour, Pascal, Lebrun, Eric, Mahe, Valerie
• Primary Examiner(s): England; David E
• Application Number:
  US10/460,443
• Publication Number:
  US 20030236888A1
• Time in Patent Office: 2,833 Days
• Field of Search: None
• US Class Current: 709/224
• 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 67/1029 using data related to the state of servers by a load balancer
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A method for improving network server load balancing in a system that has a plurality of network servers connected by an Internet access LAN to the Internet, a back-end access LAN connected to several database servers, and a network load balancer for selecting one of the network servers according to weights associated with the network servers. Link connectivity is monitored cyclically from each network server, and a status indicator is set to UP if all of the links associated with the network server are available, or to DOWN if at least one link is unavailable. The network servers send their status indicators to the network load balancer. The network load balancer changes the weight associated with a network server to a non-eligible value if the associated status indicator changes from UP to DOWN.

Claims

1. A load-balancing method, comprising:

providing a network that includes a plurality of non-load balancing network servers connected between an Internet access LAN and a back-end access LAN, and a network load balancer for selecting one of the network servers according to performance metrics based on weights that are associated with the network servers, where the Internet access LAN is connected to the Internet through an Internet access router and the back-end access LAN is connected to a plurality of database access servers;

cyclically monitoring, by every one of the plurality of network servers, availability of external links connected to a corresponding network server by attempting, by the corresponding network server, to contact each of a plurality of various network targets outside the network in turn;

setting a status indicator associated with the network server to up if all the links that have been cyclically monitored are available, and setting the status indicator to down if at least one of the links is unavailable;

sending the status indicator to the load balancer;

and changing a weight associated with the network server in the load balancer to an ineligible value if the status indicator has changed from up to down since the status indicator was last received by the load balancer.

2. The method of claim 1, wherein the step of monitoring availability of links includes the steps of:

selecting a network target for a link;

sending an echo request message over the link to the network target; and

indicating that the link is available if a response message is received from the network target within a predetermined period of time.

3. The method of claim 2, wherein the network target is one of the plurality of various network targets, which are:

the Internet access router, the database access servers, and an Intranet access router that is connected to the back-end access LAN.

4. The method of claim 1, further comprising the steps of checking whether the network server is enabled before monitoring availability of links connected to the network server, and setting the status indicator to down if the network server is disabled.

5. The method of claim 4, further comprising the step of changing the weight associated with the network server in the load balancer to a predetermined maximum value when the status indicator changes from down to up.

6. The method of claim 5, further comprising in case that the status indicator associated with the network server is down, performing the cyclically monitoring, setting, sending and changing processes again after a predetermined period of time has elapsed following completion of a Network Target Monitoring Cycle.

7. The method of claim 1, wherein the network server waits for a target monitoring cycle delay time after executing the step of monitoring availability of links connected to the network server.