Introduction to the Network Topologies

2.  The physical layout or the way in which
network connection are made is called a
topologies.
 Types:
◦ There are three types of topologies.
1. Bus topology
2. Star topology
3. Ring topology

3.  A topology that connects each computer to a
common communication medium.
 In a local network , this medium is a central
wires called a bus.
 If a computer wants to send data to other
computer in the network, it sends the data
and destination address via the bus.
 Each computer checks this address and if it
matches with this computer, the computer
keeps the data.
 Otherwise the data move to the next.

5.  In the star topology cable from each
computer is connected to a centralized device
called a hub or switch.
 If two computer want to share data, the
sender computer sends data to the hub and
hub sends it to the receiving computer.
 A hub provides a central connection point so
that all computers can communicate across
the network.

7.  A ring topology is a computer network
configuration where the devices are
connected to each other in a circular shape.
 Each packet is sent around the ring until it
reaches its final destination.

9.  Short for Binary coded decimal, BCD is also
known as packet decimal and is numbers 0
through 9 converted to four digit binary.
 Below is a list of the decimal numbers o to 9
and the binary conversion.

10.  Decimal Binary
 0 0000
 1 0001
 2 0010
 3 0011
 4 0100
 5 0101
 6 0110
 7 0111
 8 1000
 9 1001

11.  EBCDIC (Extended Binary Coded Decimal
Interchange Code ) is a binary code for
alphabetic and numeric characters that IBM
developed for its larger operating systems.

12.  ASCII stands for American standard code for
information interchange.
 Computer can only understand numbers, so
an ASCII code is the numerical representation
of a character such as ‘a’ or ‘@’ or an action
of some sort.
 ASCII Table below in image.

14.  Data communication software manages the
transmission of data between computer.
 They are special type software.
 These are programs that control
telecommunications activities and manage
the function of telecommunication network.

15.  A simplex transmission circuit permits data
follow in only one direction.
 A terminal connected to such a circuit is
either a send only or a receive only device.
 An example is a traditionally television
broadcast, in which the signal send from the
transmitter to your television antenna.
 There is no return signal.
sender receiver

17.  In half-duplex transmission, data travels in
both direction but only in one direction at a
time.
 Example of half duplex is wireless set
sender receiver
Half-duplex

18.  In full-duplex transmission data is
transmitted in both direction at the same
time .
 An example is two people on telephones
talking and listening simultaneously.

19.  In parallel transmission made each bit to be
send on separate channel.
 As show
sender receiver
0
1
0
1

20.  Here all bits of the characters are transmitted
simultaneously.
 It has transmitting speed but expensive
because large number of channels are
required.
 It is used for short distance communication.

21.  In serial transmission each bit is transmit on
single channel.
 It is show as:
 The character bit is transmitted one after
another on signal channel.
sender receiver
0110 1100

22.  In a mesh topology, each computer is
connected to every other computer by
separate cabling.
 There is no concept of a central switch, hub
or computer which acts as a central point of
communication to pass on the messages.

24.  Hybrid topology is a type of network topology
that uses two or more other network
topologies, including bus topology, mesh,
ring topology etc.

26.  A node is any devices connected to a
computer network.
 A node can be a computer or some other
device, such as a printer.
 Every node has a unique network address ,
sometimes called a data link control (DLC) or
(MAC) Media Access Control.

27.  The physical layer is simply responsible for
sending bits from one computer to another.
 The physical layer deals with bit-level
transmission between different devices

28.  The data link layer is responsible for the flow
of data over a single link from one device to
another.
 It accepts packets from the network layer and
packages the information into data units
called frames.

29.  The network layer is the third level of the OSI
model and the layer that provide data routing
paths for network communication.
 Data transferred in the form of packets via
logical network paths in an ordered format
controlled by the network layer

30.  The transport layer ensures that packets are
delivered error free, in sequence and with no
losses or duplications.
 The transport layer breaks large message
from the session layer into packets to be sent
to the destination computer.

31.  The session layer allows applications on
separate computers to share a connection
called a session.
 Establishes, manages, and terminators
communication between devices.
 This layer also controls the dialog between
two processes determining who can transmit
and who can receive at what point during the
communication.

32.  The presentation layer translates data
between the formats the network requires
and the formats the computer expects.
◦ Translation
◦ Encryption
◦ Compression

33.  The application layer is the topmost layer of
the OSI Model and it provides services that
directly support user applications, such as
database access, email, and file transfers.