The challenge of virtualization

In the last newsletter we discussed the impending perfect storm in which IT organizations implement three key initiatives, each of which are extremely beneficial, and yet end up in a place where for all practical purposes applications cease to function. In this newsletter, we will discuss primarily the first of those initiatives – virtualization. We will, however, also allude to some other closely related changes that are impacting the IT infrastructure.

At the hundred thousand foot level, there are two approaches to virtualization. In one approach, a given resource is made to look like it is multiple resources of the same type. Running multiple virtual LANs (VLAN) over the same LAN infrastructure is an example of this type of virtualization. Running multiple VPNs over a given WAN link is another. The other type of virtualization calls for combining a number of resources of the same type and having them perform as if they were one larger resource. It is a bit of a stretch, but inverse multiplexing is an example of this form of virtualization.While we have had network virtualization for a long while, there is growing enthusiasm to virtualize a wide range of other types of IT resources, including desktops, servers and storage (Compare Storage Virtualization products). Given this trend, in the not too distant future, the information flow in the n-tier applications that are so common today will be notably different. For starters, the branch office user will be on a virtualized desktop that actually runs on servers in the data center. The user will access the branch office router over a VLAN, which may or may not be a change from the current approach. 

The branch office router, however, may well have changed. In addition to routing, the router may also host some applications or Web services. Also, since the deployment of WAN Optimization Controllers (WOC) (Compare Application Acceleration and WAN Traffic Optimization products) is increasing, in the near future it will be much more likely that the data flow transits a WOC. However, this will not be the type of WOC that we have all come to know and love. For example, in addition to providing standard WOC functions such as caching, compression and protocol acceleration, this WOC will also provide virtualized network services such as DNS and DHCP. Given the ever-increasing concern about security, in the near future it will be even more likely than it is today that there will also be a firewall in the branch office. This may be a traditional firewall, or firewall software running on a virtualized server.

The data flow next transits a WAN link that today is virtually always a terrestrial link. However, for both backup and performance reasons, we will see the deployment of 3G links, which will exacerbate the WAN performance issues. Upon entering the data center, the traffic hits a virtualized application front end (AFE) which is often referred to as an application device controller (ADC). It is interesting to note that some vendors such as Cisco are taking a given AFE and turning it into a number of virtualized AFEs. Other vendors, such as A10, are combining individual AFEs into a single more powerful virtualized AFE. 

After transiting the AFE, the next step for the traffic is to be fed to an application that is running on one of a number of virtual servers, which may or may not be isolated from each other by virtualized firewalls. The phrases virtual servers and virtual firewalls refers to making a single server or firewall act as if it is multiple servers or firewalls. When the application requires data it gets it from virtual storage that is typically created by combining a number of individual pools of storage into one large pool of storage.

It is interesting to note that the concept of an AFE goes back to the era of IBM’s SNA (System Network Architecture) when there would be a front end processor (FEP) in front of a mainframe computer. The role of the FEP was to offload communications-oriented, computationally intensive tasks from the mainframe computer. Today’s AFEs got started by offloading communications-oriented, computationally intensive tasks from servers. It is also interesting to note that the concept of a virtualized server is not new.

Thirty years ago IBM operating systems made a given mainframe appear to be multiple computers. An obvious conclusion is that IBM pioneered a lot of concepts that are as relevant today as they were thirty years ago. It is very important to note that the communications and computing environment that IBM created thirty years ago was very complex. This environment was manageable in large part because IBM developed a lot of management tools and because virtually all of the piece parts came from the same vendor. In today’s world, the piece parts come from myriad vendors.

We are not saying that there are not tools to manage all of the added complexity described in the preceding example. In some cases there are. VMware certainly has tools to manage the virtualized desktop environment and Cisco has tools to manage its ADC, which it refers to as ACE (Application Control Engine). In addition, a number of other vendors are paying a lot of attention to this area. 

However, what we are saying is that the number of components in the end-to-end data flow is increasing significantly and with that comes added complexity. For example, in a recent newsletter (Poor change management causes network outages) we pointed out that today over half of the outages are caused by poor change management. The potential for poor change management increases dramatically as we virtualize more and more of the infrastructure. We are also saying that as we virtualize IT there are more components in general, and more components that are likely to have variable performance characteristics. So if you think it is tough to ensure acceptable application performance (Compare Application Performance Monitoring products) today, the movement to virtualization will dramatically increase that difficulty.

In our next newsletter we will discuss the impact of a Services Oriented Architecture (SOA) on application delivery.