Web Farm and Network Load Balancing Overview and Architecture Examples

Web Farm and Network Load Balancing Overview

After building multiple Web IIS Web servers into the Web Farm, these servers will provide users with an uninterrupted and reliable web server. When the Web Farm receives a request from a different user to connect to the website, these requests are distributed to different Web servers in the Web Farm for processing, so that the efficiency of the web page can be improved. If there is a Web server in the Web Farm, the user cannot be authenticated. If the service is provided, the server will continue to be served by other servers that are still running normally, so the Web Farm is also fault tolerant.

Web Farm Architecture

An example of a general Web Farm architecture, the following figure affects the normal operation of the Web Farm in order to avoid a single point of failure, so each level, such as a firewall, load balancer , IISWeb server and database server and so more than one, in order to provide fault tolerance, load balancing function:

1, firewall: a firewall can ensure the security of internal computers and servers.

2, load balancer: Load Balancer (Load Balancer) can distribute requests to connect to the website to different web servers in the Web Farm.

3, front-end Web Farm (IIS Web Server): Multiple IIS Web servers are composed of Web Farm to provide web access services to users.

4, back-end database server: used to store settings, web pages or other data.
Windows Server 2008R2 has built-in network load balancing (Windows NLB), so cancel the load balancer here, which enables Windows NLB in the front-end Web Farm and uses it to provide load balancing and fault tolerance.

there because Mircrosof ISA Server or Microsoft Forefront Threat Management Gateway (TMG) firewall Web Farm can be supported through the issuance of rules, it can be shown below the planning and design Web Farm environment. Upon receipt of the request for external links to internal Web site Pictured ISA Server or TMG on

, it will set the issue in accordance with rules to forward this request to a Web server process in the Web Farm. ISA Server or TMG also has the ability to automatically detect if the web server is out of service, so it will only forward requests to the still working web server.

Location of web content storage

As shown above, you can store web pages on the local disk of each web server (we simplify the firewall and load balancer in one figure) You must make the content of the web pages stored in each web server the same. Although you can copy the web files to each web server by manual copying, it is recommended to use DFS (Distributed File System) to automatically copy. At this time, as long as the web files of one of the web servers are updated, they will be automatically copied to other web servers through the DFS copy function.

You can also store web pages in storage devices such as SAN (Storage Area Network) or NAS (Network Attached Storage) and use them to provide troubleshooting for web content.

You can also store web pages in a file server as shown below, and in order to provide fault tolerance, you should set up multiple file servers, and you must also ensure that all web pages in the server are In the same way, you can use the DFS copy function to automatically make the content of the web pages stored in each file server the same.

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