Best Application Delivery Controllers (ADC)

For industries that have hundreds of web servers and need to manage thousands of customer requests on a normal basis, ADCs are essential. The load-balancing that ADCs provide makes spikes in traffic manageable and ensures that applications continue to run smoothly. Application delivery controllers also supply organizations with security and access to applications at peak times. In addition, ADCs work to complete tasks that have otherwise been performed by traditional custom-built hardware in the past. ADCs are also needed because they allow an organization to securely scale up application services very quickly, and help companies consolidate network-based services.

An ADC uses different techniques to enhance performance, one of which includes load balancing. Through load balancing, ADCs are able to speed up application delivery. It is used to distribute incoming requests across a group of servers after the requests have been sent sequentially to the servers in a list by way of a simple algorithm. The requests are allocated to a resource from an application delivery platform. How the load balancer allocates the session is based on metrics like the geographic location of an endpoint device making the request, or on metrics like current server load or the current network latency. ADC load balancing ensures that requests are shared over available data centers and servers evenly, even when multiple geographic hosting centers are being used simultaneously.

ADCs work by acting as load balancers that handle traffic flow to servers and by providing security for applications. ADCs also use several different techniques to improve the acceleration of business applications and to enhance application performance. These techniques include:

• Compression: Minimizing large files to increase delivery speed and increase network capacity.
• Caching: Caching content locally on an ADC decreases server loads and also speeds delivery.
• Load balancing: This involves distributing incoming requests using algorithms that consider client location, server capacity, and the types of content requested in order to improve overall performance.
• Offloading SSL processing: For client connections, an ADC replaces backend servers as the SSL endpoint. An ADC speeds content delivery by doing encryption and decryption work for servers, thus freeing up servers to complete other tasks.

An application delivery platform is a platform that helps speed up load times for data centers and also speed up the application delivery process. Application delivery platforms help make user experiences better because they allow IT teams to solve problems quickly.

Typically, ADCs are used by almost every industry and any enterprise or company that relies on large-scale content delivery networks (CDNs) in order to generate fast web application services and to make sure websites with high traffic rates are secure, constantly on, and also available to their users.

Among the many benefits of ADCs are security, visibility, and acceleration. Beyond these major advantages, application delivery controllers are recognized for:

• Scalability: ADCs can be scaled without re-architecting your entire infrastructure or having to schedule downtime, which can be challenging. With an ADS, your organization can successfully scale up to instantly support more users and requests.
• Efficiency: An ADC improves the efficiency of servers that manage application requests. An ADC will also make better use of resources (I/O, CPU, or RAM) by helping to reduce any overhead associated with serving and assembling responses.
• Capacity: Implementing an ADC to perform load balancing helps you manage how many users you are capable of supporting and the number of requests you receive. Having an ADC allows you to architect a solution that uses a pool of servers to direct and mediate requests to support thousands of concurrent users.
• Security: Application delivery controllers include the basic security functions that are needed to protect your applications and the servers where they are deployed. This includes DDoS protection, authentication, rate limiting, SSL, content encryption, blacklisting, etc.
• Reliability: By having an ADC, you eliminate the risk of applications being unavailable. ADCs ensure reliability by sending requests to available servers only and redirecting requests if a server is down. For organizations that have two data centers, ADCs can accommodate heavy load-balancing capabilities and can redirect requests from a primary data center to a secondary data center if necessary.
• Performance: By deploying an ADC, your applications are likely to improve dramatically because of reasons like caching, compression, connection management, protocol optimizations, and intelligent load balancing algorithms. ADCs improve an application’s overall performance.
• Increased speed: Using compression technologies, ADCs move data through the network with increased speeds.
• More efficient traffic management: Because ADCs manage traffic management with load balancers and also work to provide health checks, they are able to reroute traffic automatically when necessary.
• Better network security: ADCs improve network security by using delayed binding, application firewalls, SSL encryption, and IP filtering.

Application delivery controllers include many features. Below are just some of them to consider when looking to make a decision on which ADC you choose:

• DDoS protection
• Application acceleration
• Caching
• Intrusion detection
• TCP multiplexing
• DNS firewall
• Web application firewall
• Proxy and reverse proxy
• Compression
• SSL offloading
• Traffic shaping
• Bandwidth management
• Application and server health monitoring
• Security, SSO, application authorization
• Load balancing/global load balancing
• Multi-tenancy architecture support