Application delivery controller
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An application delivery controller (ADC) is a computer network device in a datacenter, often part of an application delivery network (ADN), that helps perform common tasks, such as those done by web accelerators to remove load from the web servers themselves. Many also provide load balancing. ADCs are often placed in the DMZ, between the outer firewall or router and a web farm.
 A common misconception is that an Application Delivery Controller (ADC) is an advanced load-balancer. This is not an adequate description. An ADC is a network device that helps applications to direct user traffic in order to remove the excess load from two or more servers. In fact, an ADC includes many OSI layer 3-7 services which happen to include load-balancing. Other features commonly found in most ADCs include IP Traffic Optimization, Traffic Chaining/Steering, SSL offload, Web Application Firewall, CGNAT, DNS System, and proxy/reverse proxy to name a few. They also tend to offer more advanced features such as content redirection as well as server health monitoring. In the context of Telco Infrastructure, ADC could provide services for Gi-LAN area.
First generation ADCs, starting around 2004, offered simple application acceleration and load balancing. In 2006, ADCs began to mature when they began featuring advanced applications services such as compression, caching, connection multiplexing, traffic shaping, application layer security, SSL offload and content switching combined with services like server load balancing in an integrated services framework that optimized and secured business critical application flows.
Application acceleration products were available from many companies by 2007. Cisco Systems offered application delivery controllers, until leaving the market in 2012. Market leaders like F5 Networks, Radware and Citrix had been gaining market share from Cisco in previous years.
The ADC market segment became fragmented into two general areas: 1) general network optimization and 2) application/framework specific optimization. Both types of devices improve performance, but the latter is usually more aware of optimization strategies that work best with a particular application framework, focusing on ASP.NET or AJAX applications, for example.
- Ann Bednarz (July 3, 2007). "Gear makers bundle network optimization features". Network World. Retrieved May 26, 2013.
- Jeffrey Burt (September 20, 2012). "Cisco Ending ADC Business, Ceding Market to F5, Citrix, Riverbed –". eweek.com. Retrieved June 27, 2013.
- Sean Michael Kerner (May 1, 2008). "Applications And Networks Need to Unite". InternetNews.com. Archived from the original on May 5, 2008. Retrieved May 26, 2013.