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Lecture 1: Network Operating Systems (NOS)
AN INTRODUCTION
Overview of basic networking concepts
OSI network model
PAN, LAN, MAN, WAN
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Scale(size) Based Network Classification
1. PAN
2. LAN
3. MAN
4. WAN
5. Internet
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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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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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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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Metropolitan Area Network (MAN)
A metropolitan area network (MAN) is a highspeed 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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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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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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Wide Area Network (WAN)
Advantages
◦ Increased efficiency.
◦ Ease of communication.
Disadvantages
◦ Security problems.
◦ Training costs.
◦ Maintenance problems
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Introduction to Operating
Systems
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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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Functions of Operating Systems (OS)
1. Resource management
2. • Memory management
3. • Device management
– Printer
– Hard drive
– display
4. • Process management
5. • Processor management (CPU time )
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Why OS was Born?
Batch processing
– Resident Monitor
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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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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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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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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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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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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.
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.
Choosing a NOS
The main features to consider when selecting a NOS
include:
◦ Performance
◦ Management and monitoring tools
◦ Security
◦ Scalability
◦ Robustness/fault tolerance
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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