Load Balancer

You can use Load Balancer to facilitate load balancing, including content-based routing to distribute requests to one or more proxies.

Load Balancer creates edge-of-network systems that direct network traffic flow, reducing congestion and balancing the load on various other services and systems. Load Balancer provides site selection, workload management, session affinity, and transparent failover.

Load Balancer is installed between the Internet and the enterprise's back-end servers, which can be content hosts or Caching Proxy machines. Load Balancer acts as the enterprise's single point-of-presence node on the Internet, even if the enterprise uses multiple back-end servers because of high demand or a large amount of content. You can also promote high availability by installing a backup Load Balancer to take over if the primary one fails temporarily.

Load Balancer intercepts data requests from clients and forwards each request to the server that is best able to fill the request. In other words, it balances the load of incoming requests among a defined set of machines that service the same type of requests. Load Balancer can distribute requests to many types of servers, including WebSphere® Application Servers and Caching Proxy machines. Load balancing can be customized for a particular application or platform by using custom advisors. Special purpose advisors are available to obtain information for load balancing WebSphere Application Servers.

If the Content Based Routing component is installed together with the Caching Proxy, HTTP and HTTPS requests can even be distributed based on URLs or other administrator-determined characteristics, eliminating the need to store identical content on all back-end servers. The Dispatcher component can also provide the same function for HTTP requests.

Load balancing improves the availability and scalability of your website by transparently clustering content servers, including HTTP servers, application servers, and proxy servers, which are surrogate content servers. Availability is achieved through parallelism, load balancing, and failover support. When a server is down, business is not interrupted. An infrastructure's scalability is greatly improved because you can transparently add processing power to back-end servers.

Load Balancer includes the following components:

Dispatcher

For all Internet services, such as HTTP, FTP, HTTPS, and Telnet, the Dispatcher component performs load balancing for servers within a local area network (LAN) or wide area network (WAN). For HTTP services, Dispatcher can perform load balancing of servers that are based on the URL content of the client request.

The Dispatcher component enables stable, efficient management of a large, scalable network of servers. With Dispatcher, you can link many individual servers into what appears to be a single virtual server. Your site thus appears as a single IP address to the world.

Content Based Routing

For HTTP and HTTPS services, the Content Based Routing component performs load balancing for servers that are based on the content of the client request. The Content Based Routing component works with the Application Server Caching Proxy component.

Site Selector

The Site Selector component enhances a load-balancing system by allowing it to act as the point-of-presence node for a network and load balance incoming requests by mapping DNS names to IP addresses. When used with Metric Server, Site Selector can monitor the level of activity on a server, detect when a server has the least amount of network traffic, and detect a failed server.

Network Address Translation (NAT)

Using Network Address Translation (NAT) Dispatcher capability removes the limitation for the backend servers to be on a locally attached network.

Metric Server

The Metric Server component runs as a daemon on a load-balanced server and provides information about system loads to Load Balancer components.


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Timestamp icon Last updated: March 23, 2018 0:18
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