NLB is a concept where a bunch of individual servers /services are brought together to make one virtual server /service. This facilitates high performance and high reliability to critical systems that need be online 24/7.
This image is a of typical NLB cluster. To start with a minimum 2 servers are required and can be scaled to N servers depending on what technology and or appliance is being used to load balance the servers. A cost effective solution is where the NLB does not become the point of failure. NLB can be implemented with the use of OS level driver / software with ease decreasing cost and reducing maintenance.
Windows Enterprise 2003 and 2008 have the NLB feature as standard and can be used to effectively bundle together few servers together for performance and redundancy. TCP services HTTP, HTTPS, FTP, POP, SMTP and other TCP/IP services can be load balanced.
In 2008 this feature has to be installed using the server manager interface and then using the Load balancer interface nodes are added to the cluster. Th cluster will have a unique cluster name and a virtual ip which is used to present the service.
In 2003 this feature is installed default. In both servers the actual NLB is as a tick-able service that can be enabled/disabled in the network adapter properties. Performance of the cluster increases with increase of nodes. The performance of the application that is being NLB'ed itself effects the performance of the cluster.
- Belllamkonda Sudhakar