8/2/2019 Lec01-Intro to Networking
1/55
Networking Concepts
Introductory Lecture
By
Mushhad Gilani
8/2/2019 Lec01-Intro to Networking
2/55
Books & study Material
Text Book:-
Data Communication and Networking,
4/e. Author: Behrouz A. Forouzan
Reference Books/Material
Larry L. Peterson and Bruce S. Davies [2000],
Computer Networks A Systems Approach,Second Edition
8/2/2019 Lec01-Intro to Networking
3/55
Introduction Meaning:
Networking consists oftwo or more than two computersconnected to each other by a medium(cable) so that they can share a data.
Definition:A group of computers and
other devices connected together iscalled a network and the concept of
connected computers sharing resourcesis called as Network.
8/2/2019 Lec01-Intro to Networking
4/55
Uses of Computer Networks
Network for Companies
Network for People.
Social Issues
8/2/2019 Lec01-Intro to Networking
5/55
Network for Companies.
Many Organizations have asubstantial number of computersin operation, often located farapart The goal are Resources Sharing
High reliability
Saving money
Scalability
8/2/2019 Lec01-Intro to Networking
6/55
Network for People.
Starting in 1990s, computernetworks began to startdelivering services to privateindividuals at home. Below wedescribe some services. Access to remote information.
Person to person communication
8/2/2019 Lec01-Intro to Networking
7/55
Social Issues
On the other hand Thewidespread introduction ofNetworking will introduce new
social, ethical, political problems.
8/2/2019 Lec01-Intro to Networking
8/55
1-1 DATA COMMUNICATIONS
The termtelecommunication means communication at a
distance. The worddata refers to information presentedin whatever form is agreed upon by the parties creating
and using the data. Data communications are the
exchange of data between two devices via some form of
transmission medium such as a wire cable.
Components
Data Representation
Data Flow
Topics discussed in this section:
8/2/2019 Lec01-Intro to Networking
9/55
Figure 1.1 Five components of data communication
MessageSenderReceiver
MediumProtocol
8/2/2019 Lec01-Intro to Networking
10/55
Figure 1.2 Data flow (simplex, half-duplex, and full-duplex)
8/2/2019 Lec01-Intro to Networking
11/55
Figure 1.3 Types of connections: point-to-point and multipoint
8/2/2019 Lec01-Intro to Networking
12/55
Explanation:
Networking arose from the needto share data in timely fashion.Computers in a network canshare:
a) Data
(b) Messages
(c) Graphics
(d) Printers
(e) Modems.
8/2/2019 Lec01-Intro to Networking
13/55
How Data Communication took Place
8/2/2019 Lec01-Intro to Networking
14/55
Types of Networks
There are three different ways inwhich we classify the networks
1) Organizational Point of View
2) Geographical Point of View
3) Computing Point of View
8/2/2019 Lec01-Intro to Networking
15/55
Organizational Point of
ViewFrom organizational point of view,
networks are divided into twotypes
Peer-to-Peer
Server based
8/2/2019 Lec01-Intro to Networking
16/55
Peer-to-Peer These are also called
Workgroups.
A peer-to-peer network comprisesof 10 or less users and is suitable
for small-sized businessorganizations.
In this model of networking the
resources are randomly scatteredon the network with everymachine acting as a server as well
as client
8/2/2019 Lec01-Intro to Networking
17/55
Server Based networks
They are sometimes referred to asDomains.This is a centralized model of networkingwith resources placed on a dedicatedmachine called Server.There is no user limit as such, as itdepends directly on your hardware
resources and capacity to support users.
8/2/2019 Lec01-Intro to Networking
18/55
Geographical Point of View
From geographical point of view,there are three types ofnetworks.
LAN
WAN
MAN/CAN
8/2/2019 Lec01-Intro to Networking
19/55
Classification of GeographicalNetworks by Scale
8/2/2019 Lec01-Intro to Networking
20/55
LAN or Local Area Network
A LAN encompasses a smallarea such as a floor or abuilding with all themachines connected directlyvia the same mediumgenerally.
8/2/2019 Lec01-Intro to Networking
21/55
Examples: LAN
Two networks: (a) Bus (b) Ring
8/2/2019 Lec01-Intro to Networking
22/55
Local Area Network
8/2/2019 Lec01-Intro to Networking
23/55
Local Area Network
8/2/2019 Lec01-Intro to Networking
24/55
WAN or Wide Area Network
A WAN comprises of a very largephysical area that covers countries
and continents. Internet is onegood example of a WAN. Themachines in a WAN are connectedthrough different mediums andprotocols. Generally, the Dial-up-Networks are used for thispurpose.
8/2/2019 Lec01-Intro to Networking
25/55
Wide Area Network
8/2/2019 Lec01-Intro to Networking
26/55
Internet MAP
This map of the Internet appeared in the December 1998 Wired.
8/2/2019 Lec01-Intro to Networking
27/55
MAN (Metropolitan Area Network)or
CAN (Campus Area Network)A MAN is almost similar to a WANthat a MAN only encompasses anarea that is within a city.CAN is a campus area Networkwhich is used with in a campus forthe sharing of resources.
8/2/2019 Lec01-Intro to Networking
28/55
Example: MAN
A metropolitan area network based on
cable TV
8/2/2019 Lec01-Intro to Networking
29/55
Metropolitan Area Network
8/2/2019 Lec01-Intro to Networking
30/55
Internetwork
(Internet)
8/2/2019 Lec01-Intro to Networking
31/55
Computing Point of View
Networks are divided intotwo types from the point
of view of computing.
1.Centralized Networks
2.Client-Server Networks
8/2/2019 Lec01-Intro to Networking
32/55
Centralized Networks
The centralized networksrelytotally on one dedicated machinecalled server for all the processingand computing and the clients or
the terminals act as dumb entities. If the client requires a certain set
of data, whole of the data set istransferred at the client end, which
also is wastage of the networkbandwidth.
8/2/2019 Lec01-Intro to Networking
33/55
Client-Server Networks In this model of networking, only
the required set of data is returnedto the client while both the server
and the client take part in theprocessing or computing of thequeries.
This is a more efficient way ofprocessing and is hence appliedgenerally more than thecentralized method, nowadays. .
8/2/2019 Lec01-Intro to Networking
34/55
Topology
A topology is the physical layoutor design of the networks thatspecifies the cabling method as
well as the arrangement of thecomputers.
It also explains the access
method used by the computersthat represent that topology.
8/2/2019 Lec01-Intro to Networking
35/55
Types of Topology
There are following types oftopologies, generally:
Bus Topology
Star TopologyRing Topology
Mash Topology
8/2/2019 Lec01-Intro to Networking
36/55
Bus Topology The bus topology consists of a long linear cable
also called trunk or linear trunk or backbone. In this type of topology, all the computers are
connected to this main cable. Bus is a passivetopology. The main features of the bustopology are discussed as under:
Signal BouncingThis is a phenomena observed in this type oftopology.
In signal bouncing, the data signal travels acrossthe cable medium from one end to another and
if not absorbed at the other end, it will keep onbouncing back and forth across the medium andtherefore will stop any further communicationon the network. This is called signal bouncing.
8/2/2019 Lec01-Intro to Networking
37/55
Bus Topology
8/2/2019 Lec01-Intro to Networking
38/55
Terminator:In order to avoid signal bouncing, a device called terminatoris used at one end of the medium that absorbs the signal and
hence restricts it from affecting the overall networkcommunication. It could be a grounding method as well withone end grounded into a wall socket.Signal Attenuation:After the data travels a long distance on the cable , itstarts becoming weaker and weaker until it reaches a pointwhere it cannot be received in the correct form. Thisprocess is called Signal Attenuation.Repeater:
The solution to Signal Attenuation is a device called repeaterthat regenerates or amplifies the signal to make it strongenough to be received correctly at the destination end
8/2/2019 Lec01-Intro to Networking
39/55
Star Topology
In star topology there is a centralnetwork traffic managementdevice called hub/Switch.
All the nodes (computers)are
connected directly to the hubandare thereby interconnected witheach other.
Star topology does not allowdirect traffic.
8/2/2019 Lec01-Intro to Networking
40/55
Star Topology
8/2/2019 Lec01-Intro to Networking
41/55
Tree Topology
8/2/2019 Lec01-Intro to Networking
42/55
ADVANTAGES
Easily Expanded
Easier to Troubleshoot
Multiple cable types Supported byhubs
8/2/2019 Lec01-Intro to Networking
43/55
DISADVANTAGES
Hub failure
Requires more Cable
May require a device to re broad castsignals across the network
Ri T l
8/2/2019 Lec01-Intro to Networking
44/55
Ring Topology In ring topology the computers connected
with each other via a single cable runconstitute a logical ring.
Ring is an active topology and also thatevery computer on the ring acts as arepeater i.e., it regenerates the signal andtransmits it onto the cable.
Token PassingA frame or sequence of data called token
passes from one computer to another onthe ring and makes the networkcommunication possible in a way that onlythe computer with token has theopportunity to transmit data on the ring.Here is how the process works: (TokenTravling on the ring.swf)
http://../figures/Token%20Travling%20on%20the%20ring.swfhttp://../figures/Token%20Travling%20on%20the%20ring.swfhttp://../figures/Token%20Travling%20on%20the%20ring.swfhttp://../figures/Token%20Travling%20on%20the%20ring.swfhttp://../figures/Token%20Travling%20on%20the%20ring.swfhttp://../figures/Token%20Travling%20on%20the%20ring.swf8/2/2019 Lec01-Intro to Networking
45/55
ADVANTAGES
It provides an orderly network inwhich every device has access to thetaken and can transmit
It performs well under a heavenload.
8/2/2019 Lec01-Intro to Networking
46/55
DISADVANTAGES
Malfunctioning workstation andcables create problems for the entirenetwork
Changes made when adding orremoving a device affect the entirenetwork.
8/2/2019 Lec01-Intro to Networking
47/55
Ring Topology
8/2/2019 Lec01-Intro to Networking
48/55
MESH
The mesh topology provides thehighest level of fault tolerance. Ituses separate cables to connect each
device to every other device on thenetwork, providing a StraightCommunication path.
Dedicated point to point link.
8/2/2019 Lec01-Intro to Networking
49/55
Mesh Topology
8/2/2019 Lec01-Intro to Networking
50/55
Hybrid Topology
8/2/2019 Lec01-Intro to Networking
51/55
A hybrid topology: a star backbone with three bus networks
8/2/2019 Lec01-Intro to Networking
52/55
Figure 1.10 An isolated LAN connecting 12 computers to a hub in a closet
8/2/2019 Lec01-Intro to Networking
53/55
Figure 1.11 WANs: a switched WAN and a point-to-point WAN
Figure 1 12 A h t t k d f f WAN d t LAN
8/2/2019 Lec01-Intro to Networking
54/55
Figure 1.12 A heterogeneous network made of four WANs and two LANs
Active Topology Vs Passive
8/2/2019 Lec01-Intro to Networking
55/55
Active Topology Vs PassiveTopology
The difference between active topology and
the passive topology is that in an activetopology the computers are themselvesresponsible for the successful transference ofdata while in a passive topology this is not thecase.
Example: In star or the bus topology, if a computer fails,
this does not affect the whole network and thecommunications on the network still go on.While in case of a ring topology, if even a
single computer goes down, the wholenetwork comes to a state of being down as thetoken gets stuck into that computer andthereby stopping all the networkcommunication