This document provides an introduction to computer networks. It discusses how networks have become globally connected through technologies like LANs, WANs, and the Internet. It describes different network topologies including mesh, star, bus, and ring configurations. The document also outlines how the network environment is changing with new technologies that enable online collaboration, video communications, and cloud computing.

1. Trainer's name : Hamed Gazi Al-nefaie.
Teacher name : Ibrahim Adini.

3. 1.0 Introduction
1.1 Globally Connected
1.2 LANs, WANs, and the Internet
1.3 The Network as a Platform
1.4 The Changing Network Environment

4. 1.0 Introduction

5. We now stand at a critical turning point in the use of technology to
extend and empower our ability to communicate. The globalization
of the Internet has succeeded faster than anyone could have
imagined. The manner in which social, commercial, political, and
personal interactions occur is rapidly changing to keep up with the
evolution of this global network. In the next stage of our
development, innovators will use the Internet as a starting point for
their efforts—creating new products and services specifically
designed to take advantage of the network capabilities. As
developers push the limits of what is possible, the capabilities of
the interconnected networks that form the Internet will play an
increasing role in the success of these projects.
This chapter introduces the platform of data networks upon which our
social and business relationships increasingly depend. The material
lays the groundwork for exploring the services, technologies, and
issues encountered by network professionals as they design, build,
and maintain the modern network.

7.  Communication
 Work
 Learn
 Play

8.  Small Home Network .
 Small Home/ office Network.
 Medium to Large Network.
 Word wide Network .

10. computing or networking is a distributed
application architecture that partitions tasks or
work loads between peers. Peers are equally
privileged, equipotent participants in the
application. They are said to form a peer-to-
peer network of nodes.

11. 1.2 LANs, WANs, and the Internet

12. Categories of Networks: depend on its size
 LAN: Covers area < 2miles
 WAN: Can be worldwide
 MAN: Between LAN & WAN, span 10s of miles

13.  Local Area Network (LAN)
 Privately owned
 Links devices in the same office, building, or
campus
 Simple LAN: 2 PCs & 1 printer in home or
office
 Size is limited to a few kilometers
 Allow resources are to be shared (hardware,
software, or data)

14. An isolated LAN connecting 12 computers to a hub in a closet

15.  Wide Area Networks (WAN)
 Provides long-distance transmission of data over
large geographic areas (country, continent,
world)

16.  Metropolitan Area Networks (MAN)
 Size between LAN and WAN
 Inside a town or a city
 Example: the part of the telephone company
network that can provide a high-speed DSL to
the customer

17.  Interconnection of Networks (Internetworks)
 Two or more networks connected together

18.  Internet has revolutionized many aspects of our
daily lives.
 It has affected the way we do business as well as
the way we spend our leisure time.
 Internet is a communication system that has
brought a wealth of information to our
fingertips and organized it for our use.

20.  Physical Topology
 The way a network is laid out physically
 Two or more links form a topology
 Topology of a network is the geometric
representation of the relationship of all the links and
linking devices (nodes) to one another.
 Four topologies : Mesh, Star, Bus, and Ring

22.  Physical Topology: Mesh
 Every link is dedicated point-to-point link
 The term dedicated means that the link carries
traffic only between the two devices it connects

23.  Physical Topology: Mesh
 To link n devices fully connected mesh has:
n ( n - 1) / 2 physical channels (Full-Duplex)
 Every Device on the network must have
n - 1 ports

24.  Physical Topology: Mesh
 Example:
8 devices in mesh has links: n(n-1) / 2
number of links = 8 (8-1)/2 = 28
number of ports per device = n – 1 = 8 –1 = 7

25.  Physical Topology: Mesh
 Advantages
 Each connection carry its own data load (no traffic
problems)
 A mesh topology is robust
 Privacy or security
 Fault identification and fault isolation

26.  Physical Topology: Mesh
 Disadvantages
 Big amount of cabling
 Big number of I/O ports
 Installation and reconnection are difficult
 Sheer bulk of the wiring can be greater than the
available space
 Hardware connect to each I/O could be expensive
 Mesh topology is implemented in a limited
fashion; e.g., as backbone of hybrid network

27.  Physical Topology: Star
 Dedicated point-to-point to a central controller
(Hub)
 No direct traffic between devices
 The control acts as an exchange

28.  Physical Topology: Star
 Advantages
 Less expensive than mesh
(1 Link + 1 port per device)
 Easy to install and reconfigure
 Less cabling
 Additions, moves, and deletions require one connection
 Robustness : one fail does not affect others
 Easy fault identification and fault isolation

29.  Physical Topology: Star
 Disadvantages
 Dependency of the whole topology on one single point
(hub)
 More cabling than other topologies ( ring or bus)
 Used in LAN

30.  Physical Topology: Bus
 It is multipoint
 One long cable acts as a backbone
 Used in the design of early LANS, and Ethernet
LANs

31.  Physical Topology: Bus
 Nodes connect to cable by drop lines and taps
 Signal travels along the backbone and some of its
energy is transformed to heat  weak signal
 Limit of number of taps and the distance between
taps

32.  Physical Topology: Bus
 Advantages
 Ease of installation
 Less cables than mesh, star topologies
 Disadvantages
 Difficult reconnection and fault isolation
 Adding new device requires modification of backbone
 Fault or break stops all transmission
 The damaged area reflects signals back in the direction
of the origin, creating noise in both directions

33.  Physical Topology: Ring
 Each device has dedicated point-to-point
connection with only the two devices on either
side of it
 A signal is passed along the ring in one direction
from device to device until it reaches its
destination
 Each devices incorporates a Repeater

34.  Physical Topology: Ring
 Advantages
 Easy of install and reconfigure
 Connect to immediate neighbors
 Move two connections for any moving (Add/Delete)
 Easy of fault isolation
 Disadvantage
 Unidirectional
 One broken device can disable the entire network. This
weakness can be solved by using a dual ring or a switch
capable of closing off the break

35.  Hybrid Topology
 Example: having a main star topology with each
branch connecting several stations in a bus topology

38. 1.4 The Changing Network
Environment

39.  Online collaboration.
 Video communications.
 Cloud computing.

43.  http://www.diffen.com/difference/LAN_vs_
WAN
 http://www.webopedia.com/TERM/P/physi
cal_topology.html
 http://www.ciscopress.com/articles/article.as
p?p=2164577&seqNum=4
 https://en.wikipedia.org/wiki/Peer-to-peer
 http://www.ciscopress.com/articles/article.as
p?p=2164577&seqNum=7