Topology

Data Communication
• Transfer of information from one place to
another
SENDER RECEIVER
MEDIUM
COMMUNICATION MODEL
SENDER sends a MESSAGE to a
RECEIVER over a MEDIUM
MEDIA
• Transmission media is commonly classified
as
• BOUNDED or GUIDED or WIRE BASED
• And
• UNBOUNDED or UNGUIDED or WIRELESS.
In Bounded or Guided media
such as Cable systems. The
signal travels inside a physical
conductor.
Guided Media
In Unbounded or Unguided media
such as Wire less systems. The
signal is usually transmitted
through air.
Unguided Media
Computer Network
• Computer network establishes
when two or more computers are
physically as well as logically
connected with each other for data
or resource sharing.
Components of a Network
• Physical connection
• Logical connection
• Data sharing
• Resource sharing
Components of Physical Connection
• Network Topology
• Network Card (LAN Card)
• Physical Address (MAC Address)
• Cables
• Connectors
• Repeaters
• HUB
• Switch

TOPOLOGY
The physical arrangement or
layout of a Network is called
TOPOLOGY.
TYPES OF NETWORK TOPOLOGIES
• BUS or LINEAR TOPOLOGY
• STAR TOPOLOGY
• RING or TOKEN TOPOLOGY
BUS or LINEAR TOPOLOGY
BUS Topology
• A bus topology connects each computer
(node) to a single segment trunk.
• The signal travels from one end of the bus
to the other.
• A terminator is required at each end to
absorb the signal so it does not reflect back
across the bus.
• In a bus topology, signals are broadcast to
all stations.
STAR TOPOLOGY
• All of the stations in a star topology are connected
to a central unit called a hub.
The hub offers a common connection for all
stations on the network.
Each station has its own direct cable connection to
the hub. In most cases, this means more cable is
required than for a bus topology. However, this
makes adding or moving computers a relatively easy
task; simply plug them into a cable outlet on the
wall
STAR TOPOLOGY
RING TOPOLOGY
A ring topology consists of a set of
stations connected serially by cable. In
other words, it’s a circle or ring of
computers. There are no terminated ends
to the cable; the signal travels around the
circle in a clockwise direction.
RING TOPOLOGY
NETWORK INTERFACE CARD (NIC)
A Network Interface Card (NIC), also called a
Network Adapter, is used to connect a computer to
the cabling used in a local area network (LAN).
Function of NETWORK INTERFACE CARD (NIC)
• The primary function of a NIC is to allow the
computer to communicate on the network
• It does this by transmitting/receiving and
controlling traffic with other computers or
devices on the network
• When transmitting, the NIC place data on
the wire in the form of an electrical signal.
• The process is reversed on the receiving end.
The NIC translates the electrical signal it
receives off the wire into bits that can be
read by the computer
MAC ADDRESS
• Each network interface card (NIC) has a unique
‘MAC address’ ‘physical address,’ assigned to it
• 48 Bit Address (6 bytes memory consumed to store)
• Based on Hexadecimal (0--9,A,B,C,D,E,F)
• Permanent address
• Syntax:
» YY-YY-YY-YY-YY-YY
» 00 - 12- 34 - AB-9D-EF
Vendor code Serial No.
24 bits 24 bits
CABLE MEDIA
Cable is the medium through which information
usually moves from one network device to
another. There are several types of cable which
are commonly used in networking.
1. Coaxial Cable
2. Twisted Pair Cable (UTP/STP)
3. Fiber Optic Cable
TYPES OF CABLES
Major difference is the data transfer rate in all cables
CO-AXIAL Cable
The two types of coaxial cabling are:
• Thinnet (10 base 2)
• Thicknet (10 base 5)
• 10 mean data transfer rate supported in mbps.
Maximum data send/receive speed is 10mbps.
• BASE tells the nature of cable (Baseband, signal
send/receive at same frequency)
• 2 or 5 mean distance cover (attenuation rate)
•2 = 185 meter
• 5 = 500 meter
Types or Standards of CO-AXIAL Cable
Connectors used with Coaxial cable
• BNC Connector
• T- Connector
• End Terminator
BNC cable connector
BNC T connector
END connector
TWISTED PAIR
CABLE OVERVIEW
TWISTED PAIR
It consists of two insulated copper wires that
are twisted together. It can be classified in
two categories.
1.STP (Shielded Twisted Pair)
2.UTP (Unshielded Twisted Pair)

Shielding
UTP
STP
UTP
(Unshielded Twisted Pair)
UTP’s 100BaseT specification is
widely used in LAN. It has a
maximum cable length of 100 meters
(328 feet) and consists of 2 or 4
twisted wire pairs.
STP
(Shielded Twisted Pair)
STP is same as UTP but it is
covered with a shield for
resistance. It is more reliable
and faster also for longer
distances.
The RJ-45 Connector
1
8
RJ-45 CONNECTOR
• Straight Through
• Cross over
• Roll over
UTP Implementation
UTP Implementation Straight-through
Wires on cable ends
are in same order
1 8
wg
g b wo
wb
o wbr
br
1
8
Straight-through Cable:
Use to connect different devices
8
1
1 8
wg
g b wo
wb
o wbr
br
UTP Implementation Crossover
Some wires on cable
ends are crossed
8 1
wo
o b wg
wb
br w g
br
Crossover Cable
Use to connect Same devices
1
8 1
8
8 1
wg
g wb
wo
br w b o
br
FIBER OPTIC
CABLE OVERVIEW
FIBER OPTIC
Fiber-optic cable uses optical rather than
electrical pulses to transmit signals.
Fiber-optic connector
Optical fiber (core) Glass cladding
Protective outer sheath
Kevlar (jacket)
FEATURES
• It provides fast transmission speeds over long
distances.
• Cable length of 2 kilometers or more
• Not affected by electrical interference
• It ensures secure and reliable data transmission.
• It is expensive
REPEATER
• Attenuation refers to the degradation of
signal strength (amplitude) that occurs in
transmissions over long distances.
Shortening the transmission distance or
using repeaters can help solve this problem
Weakened signal
Regenerated signal
Repeater

Hub & Switch
• A Hub/Switch is a central device used on star
network topology that repeats or amplifies signals,
allowing the network to be expanded with
additional stations.