Until recently when someone talked about virtualization they were most likely talking about server virtualization. While server virtualization remains the most popular form of virtualization, other forms are catching on rapidly. With that in mind, this WAN newsletter will discuss another form of virtualization – virtualized service delivery appliances.
The phrase service delivery appliances can legitimately be used to refer to a wide range of devices. That said, in this newsletter when we mention service delivery appliances, we are specifically talking about WAN optimization controllers (WOC) and Application Delivery Controllers (ADC). Until a couple of years ago, WOCs and ADCs were hardware-based appliances. While that is still the most common form factor, there has been a continuing growth in the deployment of virtualized WOCs and ADCs.
It can be confusing to discuss virtualized service delivery appliances in part because the terminology gets used in many different ways. For example, consider a virtualized ADC. It would be very helpful if when someone used the phrase virtual ADC it was 100% clear what that phrase meant. Unfortunately, that is not the case. There are at least three different interpretations of that phrase that all make sense. For example, the phrase virtual ADC could refer to taking ADC software and running it in a virtual machine. This is similar to how the phrase virtual WOC typically gets used; e.g., taking WOC software and running it in a VM.
The phrase virtual ADC could also refer to taking a large ADC and making it appear as if it is a number of smaller ADCs. This approach to virtualization is similar to how a large physical server is virtualized so that it appears to a number of smaller servers or virtual machines (VM). The phrase virtual ADC could also refer to taking a number of smaller ADCs and having them appear to be one large ADC. This approach to virtualization is similar to combining multiple servers into a server cluster.
Zeus, Citrix, A10 and F5 all provide one or more forms of a virtualized ADC. Certeon and Blue Coat both provide virtualized WOCs. Those six vendors will be on a panel at Interop that Jim is moderating. The panel is entitled Evaluating Virtualized Service Delivery Appliances and it will be held on May10 at 10:15 a.m. The panelists will discuss the benefits of this new class of service delivery appliances as well as where these appliances should and should not be deployed. The panelists will also discuss the challenges associated with this emerging class of appliances and identify specific criteria that you can use to evaluate them. If you are going to attend the conference, put this session on your must attend list.
