The Rise of Application Delivery Controllers

Application Delivery Controllers are devices that were developed to meet the new challenges facing the data center and network. These devices were built from the beginning to work with the more complex protocols and requests that older load balancers struggled with processing. They are able to perform several functions that increase performance quality for users and make the network more efficient for management.

How does an Application Delivery Controller Work?

In addition to load balancing, an Application Delivery Controller can perform a wide range of other functions. The ADC is more advanced than a router or a switch, in that it can terminate TCP connections as well. Relays and switches can only send them along to a server.

The ADC is the last point of connection for a user. The ADC then connects to the servers. The controller is also able to analyze the request and determine which server is the appropriate home for the connection more efficiently than a traditional load balancer. In a similar manner, the ADC relays communication from the server to the user. Through this position in the middle of the connection, the ADC can analyze encryption/decryption tasks, security, HTTP headers, perform layer 7 load balancing operations and more. When the server sends a response, the ADC can apply multiple processes like content compression, re-encryption and HTTP protocol header manipulation to the response.

Previously, many of these tasks were handled by separate hardware. This was a confusing and inefficient setup for many networks. The ADC consolidates all these operations into one location. Housing these tasks in one Application Delivery Controller instead of multiple pieces of hardware vastly improves the performance of the network and eliminates major IT headaches.

The New "Load Balancer"

Because ADCs are so powerful and useful, they are replacing the traditional "load balancer" in many IT configurations. With the ability to move load balancing, SSL offload, TCP offloading and more into one controller, there's little need for a different piece of hardware dedicated to load balancing. Alteon and AppDirector are two of these ADC solutions offered by Radware.

Load balancing is a natural task for the ADC. The device is connected to all the servers, so it has access to the resources available. After configuration, the controller is able to make informed decisions about which server is best equipped to handle a request. With the existing connection, the ADC easily transfers the request. Since the ADC resides at the point of transaction, parsing the HTTP headers is simple and complex tasks like URL switching are performed quickly. ADCs are often employed for both server and global load balancing, allowing them to distribute requests among servers not geographically connected.

ADCs are split into two distinct categories, advanced and basic.

Basic ADCs - This type of ADC operates on a per-packet and per-flow basis, with the main task focusing on improving the availability of applications.

Advanced ADCs - These solutions perform on a per-transaction basis, which allows them to better accomplish application fluency. Radware's Alteon is an advanced ADC, meaning it has the following capabilities and more:

  • Selective compression
  • Selective caching of dynamic content
  • Web application firewall

Radware Application Delivery Controllers

Radware's Alteon ADC and AppDirector are two premier Application Delivery Controllers on the market. Both these systems are more than capable of performing load balancing for a network - as well as many other functions like web and SSL-based application acceleration. Explore these two products today to learn how they can help your network - and your business - grow.