Network Load Balancing Services
From Wikipedia, the free encyclopedia
Network Load Balancing Services (NLBS) is a proprietary Microsoft implementation of clustering and load balancing that is intended to provide high availability and high reliability, as well as high scalability. NLBS is intended for applications with relatively small data sets that rarely change (one example would be web pages), and do not have long-running-in-memory states. These types of applications are called stateless applications, and typically include Web, File Transfer Protocol (FTP), and virtual private networking (VPN) servers. Every client request to a stateless application is a separate transaction, so it is possible to distribute the requests among multiple servers to balance the load.
Configuration Tips:
- The network load balancing service requires for all the machines to have the correct local time. Use the "NET TIME" command to synchronize servers with a commonly used server, like your domain controller. Unsyncronized times will cause a network login screen to pop up which doesn't accept valid login credentials.
- The network load balancing manager must be run from a client machine independent of the server console.
- The server console can't have any network card dialogue boxes open when you are configuring the "Network Load Balancing Manager" from your client machine.
- You have to manually add each load balancing server individually to the load balancing cluster after you've created a cluster host.
- The server registry requires a DWORD key named "UnicastInterHostCommSupport" and set to 1, for each network interface card's GUID (HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\WLBS\Parameters\Interface\{GUID})
- NLBS may conflict with Cisco routers, which are not able to resolve the IP address of the server and must be configured with a static ARP entry.
[edit] History
Windows NT Load Balancing Service (WLBS) is a feature of Windows NT that provides load balancing and clustering for applications. WLBS dynamically distributes IP traffic across multiple cluster nodes, and provides automatic failover in the event of node failure. WLBS was replaced by Network Load Balancing Services in Windows 2000.
