You need to know about Virtual Application Delivery Controllers

Well, looks like every device in the Data Center wants to be virtualized! So, the Application Delivery Controllers have also joined this trend. It is possible to sub-divide a large Application Delivery Controller into various independent (Virtual) Application Delivery Controllers to give differentiated services to individual applications and clients, using the same physical infrastructure. Let us read more about Virtual Application Delivery Controllers, in this article.

What are Application Delivery Controllers?

Application Delivery Controllers do a lot of critical functions in a Data Center including Server Load balancing, WAN Connectivity optimization (caching, acceleration, etc), SSL Offloading/acceleration and many other functionalities that are critical for application delivery and performance to the branches from a centralized data center over the WAN network connectivity. You can read more about the role of Application Delivery Controllers from here.

Which parameters of an Application Delivery Controller can be virtualized?

A lot of parameters that can be specified for individual Application Delivery Controllers can be virtualized and dedicated to each instance of a Virtual Application Delivery Controller (VADC). Some of them are,

• Bandwidth
• Processor capacity
• Memory capacity
• Transactions per second
• Compression parameters
• SSL encryption/decryption parameters. etc.

Virtual instances of ADC’s can be specified individually for specific applications, certain departments within an organization, certain services, etc. By partitioning traffic at the ADC, the IT department gains fine grained control over the actual resources delivered to individual applications/ clients.

Each Virtual ADC instance provides a complete set of application delivery functions that can be found on physical ADC devices and individual application SLA’s can be enforced. Each VADC has a dedicated management IP address. Even the network layer can be virtualized by specifying individual ports, VLAN’s, ARP/Routing tables exclusively for Virtual Application Delivery Controller instances.

The Virtual ADC’s can run as individual virtual instances either on an specialized ADC hardware or even on general purpose server virtualization hardware (Soft-ADC’s). Each VADC can have its own management interface and can be independently started, shut-down and restarted.

Advantages of Virtual Application Delivery Controllers (VADC):

• Consolidation & Centralization of ADC infrastructure across multiple departments/ applications.
• Having a single large ADC instead of multiple smaller ADC’s reduces the network ports, DC space, power consumption, etc.
• Some amount of Cap-ex and Op-ex reduction can be realized based on specific customer scenarios.
• VADC allows Data Center service providers and Cloud Service providers to provide differentiated services based on individual requirements.
• Faster deployments of new services / applications/ locations are possible with VADC as it is not required to add new appliances but its enough to just create new virtual instances on the existing ADC.
• Application developers can test the response of their applications with the Application Delivery Controller virtual instances and make any required changes to their applications without disturbing the existing ADC setup and without needing a new appliance for testing.
• One application per individual physical ADC generally results in under-utilization of ADC resources which can be avoided by using Virtual Application Delivery Controllers.
• Fault isolation between the various virtual ADC instances is possible and it can ensure that individual virtual ADC failure / congestion does not affect the other VADC instances.
• The resources allocated for each Virtual ADC can be increased/decreased On-demand and in most cases, dynamically. This enables the optimum utilization of ADC resources.
• Central management of all the VADC instances is possible along with the migration of VADC instances (in case of Soft-ADC) to enable service continuity during planned maintenance.
• Isolation of all management elements like configuration files, user database, logging / reporting, etc for each virtual ADC instance.
• Each Virtual Application Delivery Controller instance can have its own management interface.

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