I am a self-professed nerd or geek. I like technology and what it can do for me. I like to go to the electronics store looking for items that I
need want. When comparing the different models and brands, I will tend to drift towards the higher-priced gadgets that have all of these great features in addition to the function that I need.
For example, I recently purchased a Swiss Army knife. I needed a new pocket knife and wanted something that was functional and versatile. The knife I ended up buying has two knives, a screwdriver, can opener, bottle opener, corkscrew, wood saw, awl, toothpick, and tweezers. It is nice to have all of the additional functionality if I need it. But, in reality, 99% of the time I use my Swiss Army knife just to cut things with the knife blade.
Load balancer before ADC
Originally, application delivery controllers (ADC) were server load balancers (SLB). They were reverse proxies that managed connections to servers in order to provide availability and scalability for applications. The main purpose of the load balancers of the late 1990’s and early 2000’s was to manage application server pools.
At the turn of the century, we added global server load balancing (GSLB) to the functions that a load balancer provided. GSLB is the dynamic manipulation of DNS responses to direct clients to best suited IP addresses based on various metrics and algorithms. Load balancers combined the SLB and GSLB solutions into a single platform.
As load balancing technologies matured, new functions were added to the load balancer capabilities. DoS mitigation, intrusion prevention system (IPS), web application firewall (WAF), and other solutions have become part of the toolset available to the load balancer. By this time, it was decided that the load balancer did more than balance loads and the term application delivery controller (ADC) was introduced.
Buy the Swiss Army knife for the blade
Most of the time, people like the idea of a tool that can do everything that they may need. If I had to take a tool, I would take my Swiss Army knife. The ADC is a technological Swiss Army knife that can perform multiple functions. Ultimately, though, it needs to act as a load balancer and do a very good job at it.
Businesses use ADCs like I use my Swiss Army knife. Most of the time, they just need standard load balancing capabilities. On occasion, they find a need for other tools, such as WAF, DoS protection, or application acceleration, but we cannot lose sight of the fact that we need to use the ADC as a load balancer most of the time.
This makes it important for ADC technology vendors to focus on load balancing as the primary purpose of the ADC. The other functions are useful and, in some cases important, but the majority of ADCs are still being used as a standard load balancer.