1. Virtualization
Chapter 17

2. Objectives Describe the concepts of virtualization
Explain why PC and network administrators have widely adopted virtualization
Describe how virtualization manifests in modern networks

3. Overview

4. Introduction to virtualization
Virtualization is the “next big thing” in the computer industry
Virtualization creates a complete environment for a guest operating system to function as if it were installed on its own computer
Guest environment is called a virtual machine (VM)
Individual machines or entire networks can be virtualized

5. Figure 17.1 VM running Linux
Figure 17-1 shows one such example: a system running Windows 7 operating system, using a program called VMware Workstation to host a virtual machine running Ubuntu Linux.
Figure VM running Linux

6. Three parts to Chapter 17 What is virtualization?
Why do we virtualize?
Virtualization in modern networks

7. What is virtualization?

8. What is virtualization?
Most people have heard of “virtual reality”
“Virtual” world created by software, with sight & sound provided by video and audio equipment
Primarily used for gaming, flight simulation, etc.
Equipment such as goggles and special gloves enable you to “see” and “move” objects
Computer virtualization is similar
“Virtual” operating system

9. Figure 17.2 Virtual reality training
For most of us, the idea of virtual reality starts with someone wearing some kind of headgear and gloves, as shown in Figure 17-2.
Figure Virtual reality training

10. Figure 17.3 Using virtual reality to practice spacewalking
Uses for virtual reality include those such as teaching someone how to fly a plane or do a space walk without having to do the real thing at the beginning (Figure 17.3).
Figure Using virtual reality to practice spacewalking
(Image courtesy of NASA)

11. Computer virtualization
“Virtualizes” computers and networks
Virtualization convinces an operating system that it’s running on its own hardware
Runs on a host operating system that physically is installed on a machine
Guest operating systems are the virtual ones
Uses hypervisors or virtual machine managers to create and manage virtual machines and their interactions with their host environments

12. Meet the hypervisor Single OS uses program called a supervisor
Handles very low-level interaction among hardware and software (i.e., task scheduling, allotment of time and resources, etc.)
Full virtualization requires an extra layer of programming to manage complex interactions of hosts and guest machines
Enter the hypervisor or virtual machine manager (VMM).

13. Meet the hypervisor (cont.)
Hypervisor handles input and output requests an operating system would make of normal hardware
Allocates real hardware to virtual machines (drives, RAM, media, etc.) in a balance with each other and the host
Enables easy addition and removal of virtual hard drives, virtual network cards, virtual RAM, etc.
Note that the host machine allocates real RAM and CPU time to every running virtual machine. If you want to run a number of virtual machines at the same time, make sure your host machine has plenty of CPU power, and more importantly, plenty of RAM to support all the running virtual machines!

14. Figure 17.4 Configuring virtual hardware in
Figure 17-4 shows the Hardware Configuration screen from VMware Workstation.
Figure Configuring virtual hardware in
VMware Workstation

15. Figure 17.5 Configuring virtual hardware in Microsoft’s Virtual PC
Virtualization even goes so far as to provide a virtualized BIOS and System Setup for every virtual machine. Figure 17-5 shows another popular virtualization program, Microsoft’s Virtual PC, showing the System Setup, just as you’d see on a regular computer.
Figure Configuring virtual hardware in Microsoft’s Virtual PC

16. Emulation vs. virtualization
Virtualization uses hardware from the host system and divides it into individual virtual machines
Abstracts hardware that is the same platform
Cannot virtualize hardware for a different platform (Intel vs. a Sony PlayStation) for a VM
Emulation is very different
Enables software written for a different platform to run – does not virtualize hardware

17. Emulation vs. virtualization (cont.)
An emulator is software or hardware that converts the commands to and from the host machine into an entirely different platform
For example, running game console software on a PC

18. Figure 17.6 Emulator running on Windows
Figure 17.6 shows a typical emulator, Snes9X, running a game called Donkey Kong Kountry on a Windows system.
Figure Emulator running on Windows

19. Sample virtualization
Following slides take you through a quick tour of virtualization
Setting up and installing a virtual machine and its guest OS
Uses Windows 7 as the host OS
Uses VMware Workstation as the VMM
Installs Ubuntu as the guest OS
In this example, we’ll use the popular VMware Workstation on a Windows 7 system and create a virtual machine running Ubuntu Linux.

20. Figure 17.7 VMware Workstation
Begin by obtaining a copy of VMware Workstation. This program isn’t free, but VMware will give you a 30-day trial. Go to to get yourself a trial copy. A freshly installed copy of VMware Workstation looks like Figure 17-7.
Figure VMware Workstation

21. Figure 17.8 Selecting a Typical or Custom setup
Clicking on New Virtual Machine prompts you for a typical or custom setup (Figure 17-8). These settings are only for backward compatibility with earlier versions of VMware, so just click Next.
Figure Selecting a Typical or Custom setup

22. Figure 17.9 Installation media
Since virtual machines are so flexible on hardware, VMware Workstation enables you to use either the host machine’s optical drive or an ISO file. I’m installing Ubuntu, so I downloaded the latest ISO image from the Ubuntu website ( and as Figure 17-9 shows, I’ve pointed the dialog box to that image.
Figure Installation media

23. Figure 17.10 Setting the virtual drive size
Because VMware knows this operating system, it will automatically configure all of the virtual hardware settings automatically: amount of RAM, virtual hard drive size, etc. You can change any of these settings, either before the virtual machine is created or at any time later. Refer back to Figure 17-5 to see these settings. You need to accept the size of the virtual drive, as shown in Figure
Figure Setting the virtual drive size

24. Figure 17.11 Entering VM name and location
Note that VMware uses a folder off the User’s Documents folder called Virtual Machines (Figure 17-11).
Figure Entering VM name and location

25. Figure 17.12 Ubuntu installing into the new virtual machine
VMware is very convenient, even ensuring the boot order in the virtual system setup is configured to boot first from the installation media, making the Ubuntu installation automatic (Figure 17-12).
Figure Ubuntu installing into the new virtual machine

26. Figure 17.13 VMware Workstation with a single VM
Figure shows VMware Workstation with the single VM installed but not running.
Figure VMware Workstation with a single VM

27. Figure 17.14 POST in a virtual machine
A VM goes through a POST process just like any computer, as shown in Figure If you wish, you can even access a complete virtual System Setup by pressing the DELETE key just like on a real system.
Figure POST in a virtual machine

28. Why do we virtualize?

29. Why do we virtualize? Two important reasons:
Reduce number of physical machines
Ease of managing virtual machines as files (backups, security, portability, etc.)
Other important reasons include:
Power saving
Hardware consolidation
System recovery
System duplication
Research

30. Power saving
Before virtualization, each server OS needed to be on a unique physical system
With virtualization, you can place multiple virtual servers on a single physical system, reducing electrical power use
Expanding this electricity savings over an enterprise network or on a data center is cost effective and “green”

31. Hardware consolidation
Not cost effective to use a high-end server with multiple processors, RAID arrays, redundant power supplies, and RAM for only one server
Virtualization makes it possible to increase RAM and run a number of servers on a single server

32. System recovery
The most popular reason for virtualization is to keep a high uptime percentage
If a system goes down, you need to quickly restore the system from a backup
Virtualization makes it possible to shut down the VM and reload an alternative copy
Snapshots enable you to make a point-in-time exact copy of the virtual machine that can be used in case of an emergency restore

33. Figure 17.15 Saving a snapshot
Figure shows VMware's Workstation saving a snapshot.
Figure Saving a snapshot

34. System duplication
Takes advantage of the fact that VMs are simply files that can be copied
VMs can be mass-duplicated by copying the files to the target machine
Useful for:
Mass-deploying numerous servers with similar baseline operating systems
Lab or teaching environments

35. Research
Offers opportunity to reduce research and testing machines through virtualization
Useful for:
Product testing and research
Security testing and research
Development testing before production

36. Figure 17.16 Lots of VMs used for research
Today, a single hypervisor enables support of a huge number of Windows versions on a single machine (Figure 17-16).
Figure Lots of VMs used for research

37. Virtualization in modern networks

38. Virtualization in modern networks
Products discussed so far offer virtualization over operating systems
VMware Workstation
Microsoft Virtual PC
Suitable for small implementations with few virtual machines
Large-scale implementations require a different approach

39. Virtualization in modern networks (cont.)
Virtualization in large-scale networks uses “bare metal” hypervisors
No operating system necessary
Virtualization software IS the OS
Eliminates all the unnecessary OS overhead
VMware introduced ESX in 2001
Early serious large-scale bare metal hypervisor
Small storage footprint – can be installed on and booted from a USB flash drive

40. Figure 17.17 USB drive on server system
Figure shows how we load our copy of ESX: via a small USB thumb drive. Power up the server, the server loads ESX off the thumb drive, and in short order a very rudimentary interface appears where we can input essential information, such as a master password and a static IP address.
Figure USB drive on server system

41. VMMs vs. hypervisors
Virtual machine managers (VMMs) are virtual machine software that runs on top of a host operating system
Example is VMware Workstation
Hypervisor is software that does not need a host operating system
Example is ESX Server
These are also sometimes referred to as Type 1 hypervisors (for example, ESX and Hyper-V) and Type 2 hypervisors, which are also called VMMs (VMware Workstation, VirtualPC, and Sun’s VirtualBox).
Other writers call both the hosted and bare-metal—or native—virtualization software products hypervisors, but make a distinction in other descriptive words (such as hosted or native).

42. Virtual machine managers
Many choices available for Linux, Windows, and Mac OS:
VMware Workstation
Microsoft Virtual PC
Parallels
KVM

43. VMware Workstation Industry leader in virtualization
Comes in versions for Linux and Windows
Offers features such as VMTools that make interactions between guest and host OS seamless

44. Virtual PC Microsoft VMM that runs over various iterations of Windows
Free product
Some limitations
Officially supports Windows VMs, but Linux VMs can be installed and managed

45. Figure 17.18 Windows Virtual PC

46. Parallels
Most popular virtualization manager for Mac OS X (followed by VMware Fusion)
Supports all popular operating systems, and even has good 3D graphics support

47. Figure 17.19 Parallels for Windows

48. KVM Open-source virtualization product from Red Hat
Represents Linux/Unix world
Supports a few non-x86 processors
Other open-source contenders include Xen and Sun’s VirtualBox

49. Hypervisors
Several choices, but there are two dominant heavyweights in market:
VMware’s ESX
Microsoft’s Hyper-V

50. ESX Market leader; offers several features:
Support for large storage (SAN and NAS)
Transparent and automatic fault tolerance
Transparent move of running VM from one server to another
Support for up to 32 CPUs, depending on version
•Interface with large storage: ESX virtual machines easily integrate with NAS and SANs to handle massive data storage
•Transparent fault tolerance: ESX can monitor and automatically recover failed VMs with little or no input
•Transparent server transfer: You can move a running VM from one machine to another
•High virtual CPUs: Most hypervisors support a limited number of virtual CPUs, usually two at most. ESX can support up to 32 CPUs, depending on the version of vSphere product you purchase to support it.

51. Hyper-V Microsoft’s contender in virtualization Free product
Previously only part of Windows Server 2008 – now also available as stand-alone product
Available for 64-bit systems

52. Virtual switches
Addresses problems with multiple VMs, but limited NICs on host
Allows all VMs to communicate with each other, the host, and the network (and Internet)
All get their own IP address information
Two primary methods: bridging and virtual switching

53. Virtual switches (cont.)
Bridging gives each virtual NIC a connection to the real NIC
Alternative method of bridging is to install physical NICs for each VM – each virtual NIC gets a connection to its own dedicated physical NIC
Virtual switch enables VMs to communicate only with each other with no outside connection

54. Figure Bridged NICs

55. Figure 17.21 Dedicated bridged NICs

56. Figure Virtual switch

57. Virtual PBX Older hardware PBX boxes replaced with “virtual” ones
Virtual PBX is software running on a computer
All the benefits of virtualization
Many popular PBX software applications
Also “cloud” versions of virtual PBX

58. Figure 17.23 Asterisk running on a system
One of the more common upgrades is to replace ancient PBX hardware with a single PC running many of the popular PBX programs like Asterisk (
Figure Asterisk running on a system

59. Network as a Service (NaaS)
Cloud service offering virtualized networks, servers, and services
Saves on reduced infrastructure and hardware costs – costs pennies on the dollar
Ideal for small businesses that need a large network service