The challenges of virtualization

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

As we have said in multiple newsletters, virtualization changes everything. We are going to use the next two newsletters to describe some of the changes brought on by server virtualization and to describe the project that we are undertaking to drill down further into how virtualization changes the network.

VDI cheat sheet

We recently published a report that described the benefits, challenges and solutions that are associated with virtualization. As we described in that report, one of the challenges of server virtualization is that each virtualized server includes at least one software-based virtual switch, and at least in the first generation of server virtualization, each of these switches had to be configured and managed manually as a separate entity. 

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As we have said in multiple newsletters, virtualization changes everything. We are going to use the next two newsletters to describe some of the changes brought on by server virtualization and to describe the project that we are undertaking to drill down further into how virtualization changes the network.

VDI cheat sheet

We recently published a report that described the benefits, challenges and solutions that are associated with virtualization. As we described in that report, one of the challenges of server virtualization is that each virtualized server includes at least one software-based virtual switch, and at least in the first generation of server virtualization, each of these switches had to be configured and managed manually as a separate entity. 

Another aspect of the management difficulty associated with server virtualization is that the server management team typically manages the new access layer that is comprised of virtual switches, while the rest of the data center network is the responsibility of the networking team. The combination of dual access layers (for example, the new access layer inside of the virtualized server and the traditional access layer in the data center network) and split responsibilities increases the complexity of the virtualized data center network and reduces the efficiency of management. These effects become dramatically more evident as the number of virtualized servers increases.

Traditional vSwitches can lack some of the advanced features that are required to provide the degree of traffic control and isolation required in the data center. This includes features such as private VLANs, quality of service (QoS), and extensive access control lists (ACL). Even when vSwitches support some of these features, they often must be configured manually through the virtual server management application and may not be fully compatible with similar features offered by physical access switches. This situation results in difficulties in implementing consistent end-to-end network policies.

In the next newsletter we will describe a project that we have begun the goal of which is to identify how IT organizations should re-architect their network to support server virtualization. In the mean time, more information on the benefits, challenges and solutions that are associated with virtualization can be found in the report we recently published.

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.