Network World — This vendor-written tech primer has been edited by Network World to eliminate product promotion, but readers should note it will likely favor the submitter's approach.

With the explosion of job-specific data center appliances, it is common today to find several appliances monitoring a single resource. A typical scenario, for example, is three appliances monitoring the same connection, with one monitoring flows, another doing performance analysis and a third providing intrusion detection functionality.

Since cost, space and power are major issues for data centers, reducing the appliance footprint is becoming a major consideration. While some appliances require all the processing power they can get and cannot share resources -- such as 10 Gigabit Ethernet Intrusion Prevention Systems -- there are a number of monitoring, analysis and security appliances that do not require as much processing resources and can be consolidated onto a single server.

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If all appliances are based on the same operating system, it is possible to consolidate them using intelligent network adapters that can distribute and share data between multiple applications. Such solutions exist today.

However, if the appliances are based on different operating systems or expect to have full control over available hardware resources, virtualization can be used. A number of solutions are possible depending on data sharing and distribution needs. The following describes various consolidation approaches based on VMware (VMW).

Using VMware Direct Path

VMware Direct Path allows a virtual machine to control a physical network adapter. This allows existing appliance applications to be transferred to a virtual environment.

This is the first step in consolidation. To the application, it still appears as if it is running on its own server with full control of the intelligent network adapter. The driver software has been updated to support VMware Direct Path, but otherwise, no changes need to be made. This can be repeated for multiple network appliances.

As can be seen, each network appliance can be based on a different operating system and execution environment, but still be supported on the same physical server. The only restriction is that each virtual machine needs its own network adapter as only one virtual machine can control a given network adapter at one time.

Sharing network adapters

While the above implementation works, it still requires a network adapter to be dedicated to each virtual client. This limits the number of applications to the number of slots in the server. If all the virtual clients need to access the same point in the network, a separate load balancer would be required to distribute data between the network adapters.

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