This document provides an overview of computer networks. It defines a computer network as a collection of connected computers that can communicate and exchange information. It describes different types of network connections including simplex, half duplex, and full duplex. It also outlines common network topologies like bus, star, ring, mesh, and tree. Additionally, it explains important networking hardware and standards including network interface cards, switches, routers, Ethernet, Token Ring, FDDI, IEEE 802 standards, and more.

1. PRESENTED BY
SIMRAN KAUR

2. • A collection of computers (or computer like devices) that
are able to communicate with each other through some
medium, using hardware and software
• Two computers (or computer like devices) are said to be
connected, if they are able to exchange information or
able to communicate

3. • Simplex : Data transfer only in one direction. Example,
radio broadcasting
• Half duplex : Data transfer in both directions, but not
simultaneously, i.e., in one direction at a time. Example,
talk back radio, CB radio (citizen band)
• Full duplex : Data transfer in both directions,
simultaneously. Example, telephone

4. • Data source : Provides the data to transmit
• Sender/Transmitter : Converts data to signals for
transmission
• Data Transmission System : Transmits the data, i.e.,
converted in signals
• Receiver : Converts received signals to data
• Destination : Receives and uses incoming data
• Node : A device with independent communication ability
and unique network address
• Protocol : A formal description, comprising rules and
conventions defines the method of communication
between networking devices

5. • Unicast : One device sends message to the other to its
address
• Broadcast : One device sends message to all other
devices on the network. The message is sent to an
address reserved for this goal
• Multicast : One device sends message to a certain
group of devices on the network

6. • There are three types of networks:
1. Local Area Network (LAN)
2. Metropolitan Area Network (MAN)
3. Wide Area Network (WAN)

7. • LAN is privately owned network within a single building or
campus
• LANs can be small, linking as few as three computers,
but often link hundreds of computers used by thousands
of people (like in some IT office, etc)

8. • A metropolitan area network (MAN) covers a city
• An example of MAN is cable television network in city

9. • A wide area network or WAN spans a large geographical
area often a country

10. • Internet is also known as network of networks
• It is a system of linked networks that are world wide in
scope and facilitate data communication services such as
remote login, file transfer, electronic mail, world wide web
and newsgroups, etc

11. • Network topology is the arrangement of the various
elements of a computer or biological network
• It is the topological structure of a network, and may be
depicted physically or logically
• Physical topology refers to the placement of the
network’s various components, inducing device location
and cable installation
• Logical topology shows how data flows within a network,
regardless of its physical design

12. • In bus topology, each node (computer server, other
computer like devices) is directly connected to a common
cable
• At the first, the message will go through the bus then one
user can communicate with other

13. • In this topology, each node has a dedicated set of wires
connecting it to a central network hub
• First the message will go to the hub then that message
will go to other user

14. • A ring topology features a logically closed loop.
• Data packets travel in a single direction around the ring
from one network device to the next
• Each network device acts as a repeater to keep the
signal strong enough as it travels

15. • In mesh topology, each system is connected to all other
systems in the network
• Any user can directly communicate with other users

16. • In this type of network topology, in which a central root is
connected to two or more nodes that are one level lower
in hierarchy

17. • Networking hardware may also be known as network
equipment , computer networking devices
• Some of the important networking devices include
1. Network Interface Card (NIC)
2. Repeater
3. Bridge
4. Switch
5. Routers
6. Gateway
7. Ethernet
8. Fibre Distributed Data Interface (FDDI)

18. • NIC provides a physical connection between the
networking cable and the computer’s internal bus
• NICs comes in three basic varieties 8 bit, 16 bit and 32
bit
• The larger the number of bits that can be transferred to
NIC, the faster the NIC can transfer data to network cable

19. • Repeaters are used to connect together two Ethernet
segments of any media type.
• They provide the signal amplification required to allow a
segment (cable) to be extended a greater distance
• A typical repeater has just 2 ports

20. • Bridges map the addresses of the nodes residing on
each network segment and allow only necessary traffic to
pass through bridge
• The function of the bridge is to connect separate
networks together
• Bridges do not forward bad or misaligned packets

21. • Switches are an expansion of concept of bridging
• LAN switches can link 4, 6, 10 or more networks together
• Switches have 2 basic architectures : cut through and
store-and-forward
• It alleviates congestion in Ethernet LAN by reducing
traffic and increasing bandwidth

22. • Routers forward packets from one LAN (or WAN) network
to another
• It is used at the edges of the networks to connect to the
Internet

23. • Gateway acts like an entrance between two different
networks.
• It is the computer that routes the traffic from a workstation
to the outside network that is serving web pages.
• ISP (Internet Service Provider) is the gateway for Internet
service at homes.

24. • IEEE 802.2 : Logical Link Control (LLC)
• IEEE 802.3 : Ethernet
• IEEE 802.5 : Token Ring
• IEEE 802.11 : Wireless LAN
• IEEE 802.15 : Bluetooth
• IEEE 802.16 : Wireless MAN

25. • IEEE Standard 802.3 defines Ethernet, rules for
configuring Ethernet network as well as specify how
elements in an Ethernet network interact with each other
• It uses Carrier Sense Multiple Access/Collision Detect
(CSMA/CD) technology broadcasting each from onto the
physical medium (wire fibre and so on)
• All stations attached to Ethernet listen to the line for traffic
and the station with the matching destination MAC
address accepts the frame

26. • Token Ring is a form of network configuration in which all
messages are transferred in an unidirectional manner
along the ring at all the times
• Medium Access Control (MAC) is provided by a small
frame, the token that circulates around the ring when all
stations are idle. Only the station (node) possessing the
token is allowed to transmit at any given time
• It can connect upto 255 nodes in a physical star or ring
connection that can sustain 4 or 16 Mbps

27. • FDDI is a form of network configuration, uses ring
topology of multimedia or single mode optical fibre
transmission links
• It operates at 100 Mbps to span upto 200km and permits
upto 500 stations
• It employs dual counter rotating rings
• 16 and 48 bit addresses are allowed
• Token is absorbed by station and released as soon as it
completes the frame transmission