Chapter 1 introdutction to data communication.ppt

 Covered in this chapter
 Fundamentals of data communications
 OSI Reference Model
 TCP/IP Model

 Data?
 simple or complex pieces of information,
usually represented in a special way.
 is a raw-facts, concepts, instructions OR unorganized
fact that required to be processed to make it
meaningful.

 Data?
 simple or complex pieces of information, usually represented
in a special way.
 is a raw-facts, concepts, instructions OR unorganized fact that
required to be processed to make it meaningful.
⇓
Communication, interpretation, or processing by human or
electronic machine.
 May be available as Structured, Unstructured and Semi-
Structured.
 represented with the help of characters
 Alphabets (A-Z, a-z)
 Digits (0-9)
 Special characters (+,-,/,*,¡,¿,=, etc.)
 Images
 Signals etc

 Data Communication ..?
 Is process of exchangin gmeaningful information between
atleast two computing machine via some sort of Transmission
Medium.
 The Term Data refers the information presented in any form.
 Communication System = Hardware(Physical Components) +
Software (Programs)
 Communication system → 5 Components
1. Sender (Tx)
2. Reciever (Rx)
3. Message
4. Protocol
5. Transmission Medium

 Communication system → 5 Components
1. Sender (Tx)
2. Reciever (Rx)
3. Message
4. Protocol
5. Transmission Medium

The Effectiveness of Communication depends on Four major X-
stics.
 The Effectiveness of Communication depends on Four major
X-stics.
Delivery
Accuracy
Timeliness
Jitter

Let’s define 7→ ”Network”
 Interconnecting group of computing
equipment using communication
medium that can share data and
computing resources. OR
 Is a collection of Systems and
Network Devices exchanging data
over someform of media. OR
 The Systems provide an interface
for users to easily share, store and
access a variety of data.

 What make the networks? → Components of Network
 HOST → Any Devices that holds the logical address(IP
address) on your network.
 INFORMATION → The data transmitted across network.
 TRANSMISSION MEDIA → The physical pathway over
which the data travel.
 PROTOCLS → An agreed upon set of rules for
communication system
 BANDWIDTH → The total amount of data that can be
transmitted @ given period of time.
↓
(Expressed bit/byte per second)
 Network Classificaition?
 Geographical spread
 Connectivity

 PANs → Personal area networks
 LANs → Local area networks
 CANs → Campus area networks
 MANs → Metropolitan area
 networks
 WANs → Wide area networks
Based on Connectivity:
•Peer-to-peer(P2P) connection
•Multi-Point connection
•Client-Server Connection

1. Personal area networks(PANs)
• Networks spanning an area of a few centimeters to several meters
around an individual
• connection that are typically used by one person at a time.
• laptop computers, smartphones, personal printers, and wireless
peripheral devices (like a keyboard, speakers)
• also include wearable devices such as smart-* devices
↓
BAN (body area network)
2. Local area networks(LANs)
• Networks that are a little larger in geographic size than PANs
spanning a room, a floor within a building, or an entire building
• X-stics Of LAN:
• The scope of the LAN is little bit larger than PAN but smaller than
the other.
• The LAN is owned by the same organization that owns the attached
devices.
• The internal data rates of LANs are typically much greater.

3. Campus area networks (CANs)
Collections of local area networks that cover a campus (such as a
college campus or a business campus)
4. Metropolitan area networks (MANs)
Networks that serve an area up to roughly kilometers—
approximately the area of a typical city.
are high-speed networks that interconnect businesses with other
businesses and the Internet.
5. Wide area networks (WANs)
Large networks encompassing parts of cities, multiple cities,
countries, continent and the world
Basically, collection of LAN and MAN.
Internet connection is an example of WAN

 WAN has three flavours
 Enterprise network: An interconnected version of all the local area
networks of a single organization
 Global network: A network formed by combining the networks of
several organizations over a wide area.
 Internet: A network of networks of broad area category. It is the
biggest network in the world.

2. Based on Connectivity
Multi-Point connection
is a connection established between more than two devices.
also called multidrop line configuration
Single link is shared by multiple devices.
↓
The channel capacity is shared temporarily by every device connecting
to the link

NETWORK TOPOLOGY and TRANSMISSION MODE

 Topology ?
 Is tha arrangement of devices to form Network Geography. OR
 Is a geometric representation that portray the relationship between all links and
nodes to each other.
 The network architecture used to interconnect the networking equipment.
 Two flavour:
 Physical Topology
• refers to the physical layout or arrangement of devices and cables in a network.
• It describes the actual physical connections between devices
• Bus Topology, Star Topology, Ring Topology, Mesh Topology and Hybrid
Logical Topology
• refers to the way data is transmitted between devices in a network.
• It describes the path that data follows as it travels between nodes regardless of the
physical layout.
• Ethernet, Token Ring, Ethernet Switched Network, ...

 Bus Topology
 Is the Simplest Type of topology.
 devices share the media for data transmission.
 Advantage of Bus topology
• Cost of layingout the Cable
• Installation or ease-of-setup
 Disadvantage of Bus topology ? YUP Refer it ...

 Star Topology
 Each device is connected to a central hub orswitch through a separate
cable.
 This central hub acts as a mediator, facilitating communication between
devices.
 Star topologies are common in Ethernet networks
 Advantage of star topology Troubleshooting is much easier The
ˆ ˆ
performance is faster because data doesn’t have to go through each node
before reaching its destination. If one node fails, the rest FINE
ˆ

 Mesh Topology
 Every device is connected to every other device in the network.
 This results in redundant connections, providing high fault
tolerance and scalability.
 are commonly used in wireless networks and critical
infrastructure where reliability is crucial.
 Advantage of Mesh topology
 If one node fails, the rest FINE
 Improve security and privacy,
 Requires n(n-1)/2 cables
 Any disadvantage ? Yup!

 Hybrid Topology
 Topologies might be combination of various topologies
 Combination of bus, star, ring, token-ring and mesh topology

How Data Transferred ? Transmission Mode
⇒
↓
is means of transferring data between two computing machine.
Three ways of transmitting Data
1.Simplex mode
2.Half-duplex mode
3.Full-duplex mode
Simplex Mode
1.Think One-way street!
2.Its Uni-direction way of data transmission .
3.Only one of the two devices on a link can transmit, the other can only receive.
4.The entire capacity of the media to send data in one direction.
5.Example:
Simplex devices: Keyboard and Oldest CRT & LCD monitor

 Half-duplex Mode
 Bidirectional Communication! Non-Simultaneous
 Each parties can both transmit and receive, but not at the same time
 The half-duplex mode is used in cases where there is no need for
communication in both direction at the same time.
 The entire capacity of the channel can be utilized for each direction.
Figure 8: Walkie-Takie Infprmation dissmination

 Full-duplex Mode
 Simultaneous Bidirectional Communication!
 In full-duplex mode, both stations can transmit and receive simultaneously.
 In this mode, signals going in one direction share the capacity of the link with
signals going in other direction,
 This sharing can occur in two ways
• The link must contain two physically separate transmission paths, one for sending and
other for receiving.
• The capacity is divided between signals travelling in both directions.
 Two methods of data transfer
 Serial Data Transmission:
 data is transmitted one bit at a time over a single communication channel
or wire.
 Parallel Data Transmission
 multiple bits are sent simultaneously over multiple communication channels or
wires.

NETWORK DEVICES and REFERENCE MODELS

 Network devices
 Hub, Repeater, Bridge, Switch, Router, Gateways
 Reference Models
 OSI Reference Model
 TCP/IP Reference Model

 What are the Central Connecting devices?
 Hub, Repeater, Bridge, Switch, Router, Gateways and Brouter acts as central
connecting devices in the network.
⇓
Responsible for connecting appliances and transmitting data
1. Repeaters
 Operates at the physical layer.
 Function: regenerate the signal over the same network before the signal
becomes too weak or corrupted do not amplify the signal.
 It is a 2 port device.
 Types of Repeaters
1.1 Signals that they regenerate: 2 Types
→ Analog Repeaters and Digital Repeaters
1.2 The networks they connect: 2 Types
→ Wired Repeaters and Wireless Repeaters
1.3 Based on LANs they connect,: 2 Types 7
→ Local Repeaters and Remote Repeaters

 Connecting Devices ...
2 Hub
 Multiport repeater.
 Hubs cannot filter data, so data packets are sent to all connected devices.
 Do not have the intelligence to find out the best path for data packets. ˆ
 How do they Function?
o Hosts can send data to the Hub.
o Then the hub broadcasts that data to all other connected hosts on the network.
Figure 9: Connective via HUbs

 Bridges
 Operates at the data link layer.
 A bridge is a repeater, with Added Functionality. (i.e. filtering content by
⇒
reading the MAC addresses of source and destination).
 used in computer networks to interconnect two LANs together and separate
network segments.
 Types of Bridge
 Transparent Bridge
o The stations are completely unaware of the bridge’s existence.
o Automatically maintains a routing table and update table in response to maintain
changing topology
 Source Routing Bridges → Routing operation is performed by the source station
 Translational Bridges → Data format translation

4 Switches
Operates at the data link layer.
A multiport bridge. → (i.e. Can boost the efficency and Performance).
Can perform error checking before forwarding data. Means?
⋆ It does not forward packets that have errors and
⋆ Forward good packets selectively to the correct port only.
Switches addresses issues:
 Of providing direct data connections,
 Minimizing data collisions, and
 maximizing the use of a LAN’s bandwidt

5 Routers
The router is a layer 3 device
 The router uses the network address to make routing decisions regarding
forwarding data packets.
 Routers normally connect LANs and WANs together and have a
dynamically updating routing table based on which they make decisions on
routing the data packets.
5 Gateway
 device or software component that serves as an entry point between two
disparate networks, allowing data to flow between them
 Any device that translates one data format to another
 The key point about a gateway is that only the data format is translated, not
the data itself.
 Protocol Translation Addressing Translation,
 Data Format Conversion
 Application Layer Gateways (ALGs)

 CSU/DSU (Channel Service Unit/Digital Service Unit)
 AkA Data Service Unit(DSU)
 is a device that converts the digital signal format used on LANs into one
used on WANs. ˆ
 Why Translation required → Network Technology is distnict

OSI Model
The model is called the ISO OSI (Open Systems Interconnection)
Reference
Model → it deals with connecting open systems.
It is a conceptual framework.
Composed of Layers
 A layer created with a different abstraction is needed.
 Each layRoyalBluebColorer should performa well-defined function.
 The function of each layer should be chosen with an eye toward defining
internationally standardized protocols.
 The layer boundaries should be chosen to minimize the information flow
 across the interfaces.

How Many Layer’s ,→ 7 Layers
Layer-7 : Application Layer
Layer-6 : Presentation Layer
Layer-5 : Session Layer
Layer-4 : Transport Layer
Layer-3 : Network Layer
Layer-2 : Data-Link Layer
Layer-1 : Physical Layer

 Application Layer
 Provides an interface between the communications software and any
applications that need to communicate outside the computer
 The application layer contains a variety of protocols that are commonly
needed by users
 The application layer provides an interface between software running on a
computer and the network itself.
 PDU ,→ Message
 Contain various protocols for
 Extract web pages,File transfer, Send & recieve a mail and others
 Presentation Layer
 is concerned with the syntax and semantics of the information transmitted.
Means to define and negotiate data formats ,→ such as ASCII text,
⇓
 EBCDIC text, binary, BCD, and JPEG
 Encryption and data Compression issues also ↓

 Session Layer
 defines how to start, control, and end conversations → Creating Session
 mainly provide services like:
 Dialog control ,→ whose turn it is to transmit
 Token Management ,→ Preventing simultaneously critical operation
 Synchronization ,→ Resuming communication in case of failures
 Transport Layer
 Function -
 To accept data from above it,
 Split it up into smaller units,
 Pass these to the network layer, and
 Ensure that the pieces all arrive correctly at the other end
 RoyalBlue
 The transport layer is a true end-to-end layer;
 It carries data all the way from the source to the destination

 Network Layer
 A key design issue is determining how packets are routed from source to
destination.
 defines three main features: logical addressing, routing(forwarding), and
path determination
 Routing : how devices forward packets to their final destination.
 Logical addressing defines how each device can have an address that can be used by the
routing process.
 Path determination refers to the work done by routing protocols to learn all possible routes
and choose the best route.
 Data-Link Layer
 This layer defines the rules that determine when a device can send data over a particular
medium.
 To transform a raw transmission facility into a line that appears free of undetected
transmission errors.
 The sender break up the input data into data frames and transmit the frames sequentially
 If recieved successfully ACK frame → Sender

 Physical Layer
 Concerned with transmitting raw bits over a communication channel
 Representing pieces of information as 1 and 0
 Question U may rise ?
 What electrical signals should be used to represent a 1 and a 0 ?
 How many nanoseconds a bit lasts ?
 How the initial connection is established ?
 How it is torn down when both sides are finished ?
 How many pins the network connector has, and what each pin is used for
 ⋆TCP/IP Model ⋆
 Started by ARPANET ,→ Grandparent of all wide area computer
networks
 ARPANET
 is a Research project sponsored by US DoD
 Later replaced Changed its name to TCP/IP

 TCP/IP Layer
 MuThe Application layer: contains programs that make use of the
network.
 The network layer deals with how to combine:
 ltiple links into networks,
 Networks of networks, into internetworks so that we can send packets between
distant computers.
 The link layer is concerned with
⇓
How to send finite-length messages between directly connected
computers with specified levels of reliability
 The Physical layer : deal with the physical characteristics of the
transmission medium
 ⇓
Connectors, pins, use of pins, electrical currents, encoding, light

Any Similarities and Different between the Model?
↓
YUP! Reading Assignment ....

Chapter 1 introdutction to data communication.ppt

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