Virtual networks and VMware virtual switches explained

Virtualization

Virtual Networks

The creation of a virtual network is simpler than it might initially seem to a laymen trying to grasp the concept. If an understanding of how virtual machines work is established first, it is easy to make the leap to a virtual network, and understanding a virtual machine is as simple as understanding the basics of how a computer works (Fratto, 2011). A computer uses an operating system or OS, which is a specialized program, to act as an interface between hardware and other software, so that individual pieces of software do not need to be compatible with all possible hardware but need only be compatible with the OS, which can interface with drivers for the hardware (Fratto, 2011). A virtual machine or virtual environment is one in which a full compartmentalized OS, software suite, etc. is loaded onto a disk image on a computer; the OS of the virtual environment interacts with the hardware rather than with the computer's central OS, as do most programs, and this gives the virtual OS it's own "identity" on the computer -- everything that happens in the virtual environment is contained in the virtual environment, and only uses the hardware of the computer without affecting its OS or other programs (Fratto, 2011).

Knowing this, it is easy to see how a virtual environment could lead to one host having users with their own unique IP addresses, etc. If each user is running a virtual machine that is wholly compartmentalized, it is in essence its own computer and its own entity; the only connection between them is that they are all using the same hardware (Fratto, 2011).

VMare's Switches

As VMware themselves put it, "A virtual switch is similar to a physical switch" (VMware, n.d.). The default virtual switch that VMware includes as part of its virtual networking package runs on existing computing hardware just as a virtual machine would, save that the virtual switch has the very specific purpose and capabilities of acting like a physical Ethernet switch in almost all regards, especially functionally (VMware, n.d.). The ESX Server 3 virtual switch creates a connection between one or more virtual machines/environments and/or a central server or processor, serving essentially as a hardware proxy or go-between for virtual machines on interconnected hardware (VMware, n.d.). Just as a physical Ethernet line could be plugged into a physical switch to give handle the routing and give the advantages of further protection and validation, the virtual switch performs all of these tasks in a highly if not an exactly similar manner (VMware, n.d.).

The ESX Server 3 virtual switch has some significant advantages over a physical Ethernet switch, however, not in that it necessarily performs better than a physical switch but simply that it is more adaptable and flexible. This virtual switch can be adapted at the port level, meaning each port could have different protocols and procedures programmed, and as each port is essentially recreated each time it is called into use the ease with which adaptations and adjustments can be made is impressive (VMware, n.d.). In short, a virtual switch works primarily just like a physical switch, but its virtual nature gives it advantages of flexibility and variety.

Hyper-V and Windows Server 2008

Understanding virtual networks and environments and actually putting them to use are two different things, and while in theory a great number of virtual machines could be set up on any one piece of computing hardware there is ultimately a limit in the usefulness of each of these virtual environments related to the speed and capacity of the hardware. At the same time, it is estimated that most servers typically utilize only approximately ten percent of their hardware capacity, largely as a result of the partitioning needs of many user requirements calling for separate servers before capacity needs do -- that is, servers have more capacity when what users need is more partitioning (Petri, 2009). With Hyper-V, which is a part of the Windows Server 2008 operating system, partitioning can be achieved through the creation of multiple virtual machines or environments on a single server, each running as a virtual server fully partitioned form the others (Petri, 2009). Given the 10% figure above, it could be assumed that each server could handle ten guests, however cutting this almost half in to six will provide much greater reliability and in certain settings this number should be reduced further to allow for increased traffic from each guest (Petri, 2009).

As the setting described requires the ability to support 25 guests, there will need to be a total of five servers which would yield a total of 30 partitions -- enough to allow for some overflow or expanions. After acquiring the servers, creating the partutions and the full network is relatively straightforward. The virtual networks can be created using the existing Hyper-V application in the Windows Server 2008 OS, and external networking to user terminals completes the package.