The strategic importance of an ADC

In our last newsletter we began to discuss the role of the network in supporting cloud computing. We will continue that discussion in this newsletter and we will focus on the topic of how Application Delivery Controllers (ADC) are rapidly becoming a key enabler of cloud computing.

Virtualization is a key component of most cloud computing solutions and the growing deployment of myriad virtualization technologies is one of the major reasons driving change in the typical data center. For example, the typical data center used to based on physical equipment that was dedicated to a particular application. While that approach is still common, most IT organizations are evolving their data centers to be based on the highly dynamic deployment of virtual resources. Those virtual resources certainly include virtual servers, but they also include virtual appliances such as WAN optimization controllers (WOC) and ADCs. 

In many cases, a virtual ADC costs less than does a hardware based ADC. Another one of the primary advantages of a virtual ADC is that it can be deployed in places where it would be difficult to deploy a physical ADC - such as at a public cloud computing site. Once there, the ADC provides all of its typical functionality; e.g., reverse caching, TCP and SSL processing. In addition, ADCs, which initially front ended Web servers are now driving further into the data center and are increasingly being extended into the database tier both in enterprise and public cloud computing sites.

Being able to deploy a virtual ADC in a public cloud computing environment means that an IT organization can have a common architecture across its own data centers and the data centers provided by one or more cloud computing service providers (CCSP). The last newsletter discussed moving workloads between data centers. It is notably easier to move workloads between data centers if this kind of common architecture exists than if it does not.

Given where it is deployed, as well as its knowledge of traffic at layers two to seven of the OSI model, an ADC is well positioned to be a single point of control. Part of the ADC's control function is to implement security policies to respond to the security challenges that were discussed in the previous newsletter. Another part of that control function is to be able to gather management statistics and export them to existing management tools. 

While having that kind of control point is always beneficial, it is particularly important in a public cloud computing environment. For example, in the typical enterprise data center, the IT organization gathers management information from a span port on a LAN switch. However, once an IT organization moves an application to the cloud it loses a lot of the control over that application, including access to the span ports on the service provider's data center LAN.

In September and October Jim will be participating in a three city seminar tour with Citrix on the topic of how ADCs can be utilized to support cloud computing. More information on that tour can be found at

New York City event - Sept. 8

Chicago Event - Oct. 11

San Francisco Event - Oct. 12

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