1. Lecture 1: Network Operating Systems (NOS)
An Introduction

2. Overview of basic networking concepts
OSI network model
PAN, LAN, MAN, WAN
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4. Scale(size) Based Network Classification
PAN
LAN
MAN
WAN
Internet
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5. Personal Area Network (PAN)
 computer network organized around an individual person.
PAN involves a computer, a cell phone..etc
Using Bluetooth and USB often used to link this kind of networks.
Communication Technology:
Wired
Wireless (WPAN):(Bluetooth, infrared)
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6. Local Area Network (LAN)
A LAN is a privately owned network that operates within and nearby a single building like a home, office or factory.
The connection must be high speed and inexpensive.
Size: few kilometers.
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7. Local Area Network (LAN)
Advantages
Easy to share
Cost of LAN setup is low.
Disadvantages
Power
Security
Speed
Covers limited area.
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8. Metropolitan Area Network (MAN)
A metropolitan area network (MAN) is a high- speed network that connects local area networks in a metropolitan area
It covers a city.
Examples:
The cable television networks available in many cities.
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9. Metropolitan Area Network (MAN)
Advantages
Efficiency and shared access.
All the computers residing in the same area have an equal chance to access the network.
Disadvantages
costly
Security problems
slow.
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10. Wide Area Network (WAN)
A wide area network (WAN) is a network that covers a large geographic area (such as a city, country, or the world) using a communications channel that combines many types of media such as telephone lines, cables, and radio waves.
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11. Wide Area Network (WAN)
Advantages
Increased efficiency.
Ease of communication.
Disadvantages
Security problems.
Training costs.
Maintenance problems
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12. Introduction to Operating Systems
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13. What is an Operating System?
• 2 kinds of a software
– Application Software
• Word processors, database manager, compiler, web browser
– System Software
• Operating system itself
• Bridges between the hardware and users
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14. Functions of Operating Systems (OS)
Resource management
• Memory management
• Device management
– Printer
– Hard drive
– display
• Process management
• Processor management (CPU time )
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Why OS was Born?
Batch processing
– Resident Monitor
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17. Time Sharing Using Operating Systems
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Operating Systems
Time-sharing operating systems schedule tasks for efficient use of the system and may also include accounting software for cost allocation of processor time, mass storage, printing, and other resources.
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Operating Systems
Operating system (OS) is a software that manages computer hardware and software resources and provides common services for computer programs.
Operating systems form an essential component of the system software in a computer system.
Application programs usually require an operating system to function.
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Operating Systems
For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware.
Operating systems can be found on almost any device that contains a computer—from cellular phones and video game consoles to supercomputers and web servers.
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21. Operating Systems: Examples
Examples of popular modern operating systems include:
Android, BSD, iOS, Windows Phone,
Linux, OS X, QNX,
Microsoft Windows, and IBM z/OS.
All these examples, except Windows, Windows Phone and z/OS, share roots in UNIX.
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22. Networks Operating Systems
Network operating system (NOS): software that implements an operating system of some kind that is oriented to computer networking.
The network operating system is designed to allow shared file and printer access among multiple computers in a network
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23. NOS Characteristics
Network operating systems (NOSs) distribute their functions over a number of networked computers.
It adds functions that allow users to access shared resources concurrently.
Client systems contain specialized software that allows them to request shared resources that are controlled by server systems responding to a client request.

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25. Differences Between PC and a NOS
The NOS enhances the reach of the client PC by making remote services available as extensions of the local operating system.
Although a number of users may have accounts on a PC, only a single account is active on the system at any given time.
NOS supports multiple user accounts at the same time and enables concurrent access to shared resources by multiple clients (multitasking and multiuser environment).

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27. Multiuser, Multitasking, and Multiprocessor Systems
A NOS server is a multitasking system. the OS is capable of executing multiple tasks at the same time.
Some systems are equipped with more than one processor, called multiprocessing systems.
multiprocessing systems are capable of executing multiple tasks in parallel by assigning each task to a different processor.
The total amount of work that the server can perform in a given time is greatly enhanced in multiprocessor systems.

28. NOS Server Hardware
NOS servers are large systems with additional memory to support multiple tasks that are all active, or resident, in memory at the same time.
Additional disk space is also required on servers to hold shared files and to function as an extension to the internal memory on the system.
Because a NOS depends on the continuous operation of its servers, the extra hardware components justify the additional expense.

29. Choosing a NOS
The main features to consider when selecting a NOS include:
Performance
Management and monitoring tools
Security
Scalability
Robustness/fault tolerance

30. Networks Operating Systems: Where to use?
NOS can be used in:
Routers, switches and hardware firewall.
PCs in Peer-to-peer networks
Client-server Architecture
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