A "virtual" appliance?!? What on earth is that? It's pretty simple. What we normally refer to as an appliance is typically a purpose-built device that wraps up a physical piece of hardware, together with the software that enables it to perform a specific task--delivered to the customer as a turnkey system. A "virtual" appliance, on the other hand, is delivered to the customer as software and in such a fashion that they can deploy it turnkey into a virtual environment--with no hardware involved. We sometimes refer to "physical appliance" and "virtual appliance" to delineate between the two.
Historically, PBXs, voice mail systems, audio conferencing systems, and video conferencing systems all shipped as physical appliances--purpose-built, turnkey, hardware and software all wrapped up as one solution. Some vendors still ship that way, and I'm sure they will continue to do so for some time to come. Use-cases for physical appliances remain valid, and in some situations, they are still very much preferred.
But such self-contained form factors aren't for everyone, so increasingly we find voice and unified communications being delivered as software-only solutions, which can be deployed on industry standard servers, or in virtualization-enabled data centers. It's interesting to note that as we transitioned from proprietary, purpose-built physical appliances to software-only delivery, some vendors went through a period of providing turnkey physical appliances consisting of their UC software on industry standard servers from well-known manufacturers like HP, IBM, Dell, etc.
That then led to customers and channel partners wanting to pick their own standardized servers, and so we came to software-only UC and software-only Voice, effectively putting the onus of the whole installation process onto channel partners and customers. The labor cost for the channel partner increased, but they and the end customer benefited from the flexibility of choosing their own industry standard server, as well as the cost reduction they realized through sourcing the servers themselves.
Now we're talking about virtual appliances--turnkey delivery of software into a virtual environment, or more specifically, into a virtual machine.
It's an appliance because it has pretty much all of the same characteristics of a physical appliance, with the exception of hardware. It is considered turnkey in that the customer or channel partner doesn't install the operating system followed by the UC application, and it does come with a software definition of the virtual hardware resources that are needed (e.g. number of CPUs, GHz clock cycles, RAM, HDD, Network.)
The definition of a virtual appliance is, in fact, based on an open industry standard called Open Virtualization Framework or Open Virtualization Format (OVF). OVF defines a packaging consisting of a set of files that include the application as well as the deployment characteristics for that application. This is referred to as metadata, and is captured in standard XML format.
The whole set of files can also be packaged up as one TAR file called an Open Virtualization Archive or Open Virtualization Appliance (OVA). You'll sometimes hear both OVF and OVA used interchangeably, but there are specific meanings to each. Of course, UC vendors offering UC/Voice virtual appliances build those virtual appliances using developer tools such as VMware Studio, which make it easier to for them to package up, offer, and maintain virtual appliances.
Packaging UC/Voice software as a virtual appliance allows the vendor to pre-build the underlying operating system and the UC Application, along with a definition of the virtual hardware resource requirements. This can then be shipped from the vendor as an .OVA file--either on CD/DVD, or as a software download from the vendor's support site. The customer's IT data center administrator can then use VMware vSphere/vCenter management console to import the .OVA file using a step-by-step OVA import wizard. Furthermore, that wizard can be used to conveniently assign other system level configuration parameters such as IP addressing, etc. It's just like shipping an appliance, but without the hardware.
So why do this? There are several very important benefits to shipping UC software as a virtual appliance:
* Installation time reduction--Shipping an .ova for installation using VMware vSphere's .ova import wizard greatly reduces the time it takes to get a UC/Voice solution up and running. In some cases, what used to take a couple of hours to install and configure can now be reduced to just a few minutes.
* Pre-set resource reservation--Pre-defining the amount of virtual hardware resources required to support the UC application ensures that the application will have the resources it needs when it's deployed in a shared virtual infrastructure environment. Pre-configuring these settings in the OVA removes the guesswork for the IT administrator and the potential trouble associated with translating written engineering documentation into virtual machine settings.
* Simplified installation--By leveraging the VMware vSphere .ova import wizard, the vendor can take advantage of querying the installer for additional site-specific information through one deployment wizard.
* Portability--OVF is an open standard and thus should lead to the ability to deploy virtual appliances that are defined using this standard across any hypervisor--in theory. Think of it this way: SIP is a standard too, but there are vendor-specific nuances. Your mileage may vary when it comes to portability.
In summary, delivering Voice/UC applications as virtual appliances provides elegant simplicity to deploying and configuring UC solutions. It's a simple, fast and cost effective means to getting a rich voice solution with comprehensive unified communications capabilities up and running for your business. UC virtual appliances, along with other software-centric advances such as Host Media Processing, SIP trunking, SIP softphones, and FMC/Mobile integration mean that users can get a rich communications platform downloaded and installed without ever seeing a piece of hardware.
We've come a long way from the nearly prehistoric days of wheeling in a six foot bay of circuits, media cards, voice switching, trunk gateways and goodness knows what else into a customer site!
Next up: How your Voice/UC solution can benefit from leveraging virtual infrastructure availability and business continuity solutions to provide an even more reliable solution.
