The emergence of virtual appliances

Insightful analysis by consultants Steve Taylor and Jim Metzler, plus links to the latest WAN news headlines

When most people talk about the adoption of virtualization, they are really talking about the adoption of server virtualization. While there is no doubt that server virtualization is the most common form of virtualization, there is also no doubt that other forms of virtualization are also gaining in importance. This WAN newsletter will talk about how virtual appliances are gaining in importance.

How VDI affects the network 

A Virtual Appliance is based on network appliance software running in a virtual machine. Virtual appliances can include WAN optimization controllers (WOC), Application Delivery Controllers (ADC), firewalls, routers, switches and performance monitoring solutions such as probes among others. An important set of synergies exists between virtual servers and virtual appliances such as a WOC, router or a performance monitoring solution. Perhaps the most important synergy is that virtual appliances are of particular interest to IT organizations in those instances in which server virtualization technology has already been disseminated to branch offices and has also been implemented in the data center. That follows because in these instances the platform to deploy virtual appliances already exists.

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When most people talk about the adoption of virtualization, they are really talking about the adoption of server virtualization. While there is no doubt that server virtualization is the most common form of virtualization, there is also no doubt that other forms of virtualization are also gaining in importance. This WAN newsletter will talk about how virtual appliances are gaining in importance.

How VDI affects the network 

A Virtual Appliance is based on network appliance software running in a virtual machine. Virtual appliances can include WAN optimization controllers (WOC), Application Delivery Controllers (ADC), firewalls, routers, switches and performance monitoring solutions such as probes among others. An important set of synergies exists between virtual servers and virtual appliances such as a WOC, router or a performance monitoring solution. Perhaps the most important synergy is that virtual appliances are of particular interest to IT organizations in those instances in which server virtualization technology has already been disseminated to branch offices and has also been implemented in the data center. That follows because in these instances the platform to deploy virtual appliances already exists.

In the branch office, a suitably placed virtualized server could potentially host a virtual WOC, router, firewall and other virtual appliances. Alternatively, a router or a WOC that supports VMs could also serve as the infrastructure foundation of the branch office. Hence, one of the advantages of virtual appliances is that they can support branch office server consolidation strategies by enabling a single device to perform multiple functions typically performed by multiple physical devices.

One of the compelling advantages of a virtualized appliance is that the acquisition cost of a software-based appliance can be notably less than the cost of a hardware-based appliance with the same functionality. In many cases the cost of a software-based appliance can be a third less than the cost of a hardware-based appliance. In addition, a software-based client can potentially leverage the functionality provided by the hypervisor management system to provide a highly available system without having to pay for a second appliance. As a result of these cost savings, IT organizations will be able to afford to deploy virtualized appliances more broadly than they would be able to deploy hardware-based appliances.

Our next WAN newsletter will look at some of the potential challenges of using virtual appliances. More information on the benefits, challenges and solutions that are associated with virtualization can be found in Jim's recent report. In addition, at the forthcoming Interop conference in New York City, Jim will be moderating a session entitled The Emergence of Virtualized Application Delivery Appliances. If you are going to be at Interop, you should plan on attending that session.

Read more about lans & wans in Network World's LANs & WANs section.

Steve Taylor is president of Distributed Networking Associates and publisher/editor-in-chief of Webtorials. Jim Metzler is vice president of Ashton, Metzler & Associates.