This vendor-written tech primer has been edited by Network World to eliminate product promotion, but readers should note it will likely favor the submitter's approach.
It was a decade ago, in 2003, when Gartner first defined the application delivery controller (ADC). At that time, ADC was little more than the marriage of load balancing and offload technology.
Fast forward to 2013 and the definition of an ADC bears very little resemblance to its original form. ADC now comprises a robust set of capabilities such as SSL VPN, IPv6 gateway, web application firewall, WAN optimization and programmability, among other things.
This evolution in the definition of ADC was not arbitrary; rather, it reflected the inclusion of new, adjacent capabilities. As related trends such as Web 2.0, social networking and cloud impacted application and data center architectures, functions such as identity and access management were offloaded and consolidated on ADC systems capable of rapidly providing these services.
The natural topological deployment of an ADC as the entry point or gatekeeper to applications made the inclusion of a variety of related features a logical step forward. As the primary point of control, services like security and access, filtering and steering were a natural fit for ADC, despite definitions of the ADC that notably excluded identity management or HTTP message steering.
Throughout this migration of services onto ADC systems, the ADC market has continued to grow. Every time a new capability is integrated into the ADC -- such as WAN optimization, web application firewalling or application acceleration -- the market expands. The upper limit on the ADC market is constrained only by current definitions -- definitions that have historically evolved and expanded. Definitions that will no doubt expand and evolve again.
The pressure from technologies like cloud, software-defined networking (SDN), and even mobile computing, is forcing organizations -- and the vendors that support them -- to react rapidly to the need for more and varied services. The traditional quick, pain-point solution purchase is no longer acceptable because it introduces operational overhead that results in higher short- and long-term costs and complicates architectures. An extensible, service-oriented model is now desired, as evidenced by the interest in SDN and adoption of cloud computing.
The ADC is based on such a model. It is a platform, not a product, and as such can extend its capabilities rapidly in response to changing business and architectural needs.
Platforms and Ecosystems
There has been a lot of buzz about SDN's ability to reduce time-to-market for new protocols and network functions by treating the SDN controller as a platform, extensible through API-integrated "applications." In fact, the concept of SDN as a platform and its promotion of an ecosystem approach is critical for future success.
As it turns out, this isn't a novel concept. The importance of platforms and ecosystems was brought to the fore in June 2007 when Google introduced Android. Today, we identify our choice in mobile phones and devices by platform -- Android or Apple -- not by manufacturer or device brand. Applications available in respective platform stores -- the "ecosystem" -- are categorized by platform, not specific product. Both are inarguably successful due to the strength of the platform approach. Undoubtedly, platforms, whether viewed through the lens of consumer or data center requirements, are a key factor to "mobile" success.
Similarly, the platform-ecosystem approach is key to ensuring that an ADC is able to continue to respond rapidly by extending the ecosystem of services to include whatever new capability might be necessary. It is the platform that enables new services to be rapidly developed or integrated and released as part of the ecosystem. It is the platform that ensures interoperability between services by providing a common framework upon which new services can be deployed.
This platform approach is not focused on the benefit it provides to the ADC vendor. While a vendor basing its offering on a platform certainly has a competitive advantage to rapidly incorporate new market-driven services, it is the customer who ultimately benefits the most from this platform approach.
By standardizing on an ADC platform, an organization can choose which services to deploy based on operational and business needs. And although the organization might deploy many instances of an ADC -- all with different sets of services -- the advantage is that the underlying management remains the same. This is akin to the notion of unifying the switching fabric with OpenFlow and SDN; consolidation on a single platform enables consistent management and configuration across what is likely a very large installed base. So too, a platform-based ADC provides the same consistency across environments.
Along with operational consistency comes rapid extensibility. The value of SDN lies primarily in its applications -- those network services that can be deployed on the central SDN controller. This model promises to enable IT to be in control of its own network destiny; to deploy services on the basis of need rather than on vendor release schedules.
It is also inherently supportive of "pay as you grow" business models, which recognize that an organization may not need service X today, but may need it next year. Rather than requiring IT to deploy a new system with X included, a platform approach enables IT to acquire service X and deploy it on its own terms. Likewise, platform-based ADCs provide these same capabilities and benefits; the ability for IT to deploy services when and where they are needed.
Clearly, ADC is a platform and must continue to be a platform in order to support the evolving need for new services and deployment models. The changing application architecture landscape, driven by cloud and API-based integration, along with agile development efforts, ultimately impacts the application and network infrastructure by introducing these new needs and requirements for services.
It is precisely because ADC is a platform that it can rapidly respond by including those services in its already extensive ecosystem -- and quickly provide access to them. Were it not a platform, it would eventually fall so far behind the pace of innovation in other areas of the data center that it would fail to provide enough value to justify its own existence.
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