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Unformatted text preview: Virtualization Virtualization
Daryl Johnson / Bill Stackpole Virtual Private Networks Virtual Private Networks
• A virtual private network (VPN) is a communications network tunneled through another network, and dedicated for a specific network. (Wikipedia) communications, but a VPN need not be secure, nor encrypted, communications • One common application is secure VPN VPN
• VPN’s use tunneling protocols – A tunneling protocol is a network protocol which encapsulates a payload protocol. (Wikipedia) • In your lab, you will see two protocols used
– GRE (Generic Route Encapsulation) – PPP (PointtoPoint Protocol) Microsoft’s Implementation Microsoft’s Implementation
Data Link Header IP Header GRE Header PPP Header Encrypted PPP Payload Data Link Trailer Ethernet Frame Application Layer Transport Layer Network Layer Data Link Layer Physical Layer What is virtualization? What is virtualization?
• Think the Holodeck on Star Trek
– Nonphysical environment in which a process or a whole system can run • Creating a VIRTUAL computer inside of a running operating system – Can include virtualization of hardware devices too (e.g., SCSI drive on IDE drive, multiple NIC’s on a single real NIC,…) Why might you virtualize? Why might you virtualize?
• Disposable system
– Trying/testing new software – Browsing unknown sites – Downloading – Doing homework/labs at home – Having multiple systems for client/server • Alternate configurations Pros & Cons Pros & Cons
• • • • • •
Cost savings Disaster recovery Time savings Physical hardware independence “What if” capability Multiple single application servers • • • • • Increased costs Single point of failure Performance Technological overhead Licensing History History • IBM – decades ago
– VM allowed upgrade of OS for new features and old OS for compatibility – One for Vista, one for XP? • Pascal/Java virtual machine • CPM/Mac daughter card – Dual boot machine to enable appropriate CPU – Shared memory space Types of software virtualization Types of software virtualization
• Emulation / full system simulation
– virtual machine simulates complete hardware – allows unmodified OS for a completely different CPU to be run – VM does not simulate all hardware – Offers special API requiring OS modification(s) • Paravirtualization Types of software virtualization Types of software virtualization (cont)
• Native virtualization (or) “full virtualization”
– partially simulates enough hardware to allow an unmodified OS to be run in isolation – Guest OS MUST be designed for same CPU Application Virtual Machine Application Virtual Machine
• a piece of computer software that isolates an application (being used by the user) from the computer. • Places the application in its own memory space • Can isolate from other host resources
– Network Products Products
• VMWare – Server – Workstation – Player – ESX – Virtual PC – Virtual Server • Microsoft Products Products
– Parallels – Xen – Virtual Server Project – User Mode Linux – Others? • Linux ...
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This note was uploaded on 05/27/2009 for the course NSSA 4050-220 taught by Professor Golen during the Fall '08 term at RIT.
- Fall '08