A common misconception is that an Application Delivery Controller 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.
History
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.
Market
In 2005, a market research firm estimated the ADC market at US$727 million, with major vendors including F5 Networks and Cisco Systems. In 2012, Cisco Systems lost market share to its competitors. F5 has since gone on to become the market leader within the ADC space. In 2015, Brocade Communications Systems acquired the SteelApp business unit of Riverbed Technologies, Inc. to expand on its ADC offerings and consolidate its position in the Software Defined Data Center/Software Defined Network arena. Brocade renamed SteelApp to Brocade Virtual Traffic Manager. In 2016, Webscale launched their Cloud-based Application Delivery Platform, with the included software-defined ADC to integrate seamlessly with the application and utilize cloud infrastructure to improve performance, availability and security
