I’ve been hearing a lot about the benefits of virtualization for network management. From improved productivity to increased efficiency, network virtualization holds much promise. However, for all the benefits that virtualization brings to the field of network management, it also brings a few challenges.
How do you keep track of your virtual assets and real ones? Do you need a special team, tools or hardware to get the job done? It turns out that the most popular virtualization system (VMware), makes this an easy job for most network management systems when configured correctly.
VMware’s workstation product gives you three choices for network virtualization: Bridged, NAT and Host Only.
Bridged: This mode creates a virtual switch that sits between the host NIC and the VM instance. The VM instance looks like another PC on the network, it shares the host NIC resources and has an IP Address assigned via DHCP or static entry. A bridged VM instance looks and feels very much like a separate server on the network. It provides full monitoring capabilities similar to that of the host.
NAT: NAT mode uses the host machine's IP address to communicate with the network. As a result, no external IP address is assigned and the VM instance is not visible to the external network. This method provides a high level of security, but does not allow you to poll the VM instance directly. This method requires additional specialized software and agents.
Host Only: This method sets up a network that is completely contained within the host. It has no ability to communicate with the outside world. You will not be able to see the VM instance at all.
As you can see, the methods used for setting up networking on a virtual instance will determine what an IT management application will “see” and monitor. While this example is specific to VMware, most products offer similar options.
If you’re a dopplerVUE user you can create a group and associate the virtual devices to a physical device. dopplerVUE groups provide a view of all alarms and performance overlays in a single view, and allows drill down access into the performance of each virtual server.
One problem that has been noticed when using Virtualization with applicaitons that perform a high volume of database read/write is that the speed within a VM instance can be quite slow. You won't notice it unless under a heavy read/write load. I've tested implementations completed by IT staff at multiple locations using an application called diskTT and found that often the read/write is lower than my laptop. If your apps are slow, be sure to check this out and tune properly. If you know how to tune and speed up a vm image read/write please add a comment...
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