Data communication basics

NTIPRIT
National Telecommunication Institute for Policy Research, Innovation and Training
Ghaziabad – 201002. www.ntiprit.gov.in
Data Communication
1
An Introduction
By Naveen Jakhar, ITS

NTIPRIT
Discussion Points
9/13/2016 Introduction Data Com 2
 Basic Data Communication Concepts
• Message, Packets, Nodes, link, Backbone
Communication Channel, Protocol
 Network Elements
• Hub, Switch, Bridge, Router, gateway
 Packet Switching Concepts
 Various Types of Data Communication

NTIPRIT
Why Data Communication?
3

NTIPRITNTIPRIT
Over the past few years, it has become clear that the world
has changed forever.
We are now in the Information Age—the second Industrial
Revolution,
The first Industrial Revolution revolutionized the way people
worked by introducing machines and new organizational
forms.
Information is power, information is tool! (information is
processed Data)
One of the challenges in studying data communications and
networking is that there are many perspectives that can be
used

NTIPRITNTIPRIT
Is the process of using computing and communication
technologies to transfer data from one place to another,
and vice versa. It enables the movement of electronic or
digital data between two or more nodes, regardless of
geographical location, technological medium or data
contents.
DC incorporates several techniques and technologies
with the primary objective of enabling any form of
electronic communication. These technologies include
telecommunications, computer networking and
radio/satellite communication.
Data communications (DC)
9/13/2016 5Introduction Data Com

NTIPRIT
Electronic transmission of information that has been
encoded digitally
(as for storage and processing by computers)
sending digital messages using communication technology
Data Communication

NTIPRIT
Basic Elements of Data Communication
Five Basic Elements
 Message
 Sender
 Receiver
 Transmission Medium –Channel
 Protocol - Rule
Basic Data Communication Model
Cooperating
Applications at
Each Node

NTIPRIT
5 Basic Components

NTIPRIT
MESSAGE
Examples of Message : Data, Program, File, Snippet of Personal
Conversation, Stream of Audio, Video, Voice, etc
The Message is the primary purpose of communication. It can take
many forms
Limitations of use of Message as Communication Tool: Varying
Message Length & Inefficient Utilization of Bandwidth
Message as Byte Stream
The meaning of message is established by the protocols recognized by
the cooperating applications at each node
Messages are converted into Analog/Digital Signals for transmission
over the communication Medium
9

NTIPRIT
DSL
Modem
DSLAM Internet
Ethernet packets
Analog Signal Digital ATM, MPLS,SONET Ethernet packets
Converter Various
converters
Web
serverHome PC Links Links
JOURNEY OF MESSAGE FROM SOURCE TO DESTINATION
10

NTIPRIT
Packets
Basic Unit of Data Communication
Broken, delimited part of Message, a formatted unit of data.
Payload Vs. Header
Makes Possible sharing of Communication channel for
messages
Consists of data in bits/bytes encapsulated by information
about the packet :
Specific Data Packets : Segment, Datagram, Frame,
Control Message Packet
11

NTIPRIT
Why Packet is the Basic Unit?
Represents a reasonable unit for routing of data
The use of packets simplifies operations and increases communication
efficiency
Enables processing of a block of data all at once, instead of a character
or byte at a time
Packets offer an alternative to dedicated channel for entire message
length
It increases the productivity of the communication channel
It simplifies synchronisation of the sending and receiving systems
12

NTIPRIT
Payload v.s Header
 Payload : User data
 Header: Control information,
which is required for delivery of
User Data or Payload, e.g.
Source address, Destination
address, error detection codes
like checksum & sequencing
information (FCS).
 Usually the payload
information is found between
Header and Trailer.
Packet
Header Payload

NTIPRIT
NODE
 Can be any communication
Device – PC, Smart Phone,
Router, gateway
 Can be either source,
Destination, or Intermediary
 Each node on a network is
identified by unique logical
address – IP address on TCP/IP
 Node connect to the network
through its Interface
Node

NTIPRIT
INTERFACE
 Connects Node to the network
 Each Interface is identified by
unique Physical Address –
MAC address in NIC
 A node may have multiple
Interfaces
 Multi Homing

NTIPRIT
LINK
 A Segment of the transmission
Channel
 A LAN or Subnet is a Link
 Devices on same Link uses Physical
Address to identify each other
 Devices connected on same Link
communicate at Layer 2, Data Link
Layer
 Hub and switch works on the Link
 Link

NTIPRIT
BACKBONE
 A Backbone is a network
Infrastructure that interconnect
diverse LANs or Sub networks
 A backbone can tie together
diverse networks in the same
building, in different buildings in a
campus environment, or over wide
areas
 Network backbones are designed
to maximize the reliability and
performance of large-scale, long-
distance data communications.
 WAN Backbones typically consist
of routers and switches connected
by fibre optic

NTIPRIT
HUB
 A common connection point
for devices in a network. Also
known as concentrator.
 A hub is the place where data
converges from one or more
directions and is forwarded out in
one or more directions.
 Hubs are commonly used to
connect segments of a LAN.
 Hub basically acts as signal splitter.
When a data frame arrives at one
port, it is redistributed to all the
other ports so that all devices of the
LAN can see all frames.
 Types of Hub
• Active, Passive, Intelligent
 Hub

NTIPRIT
SWITCH
 A network switch joins multiple
Devices together within one LAN.
 Allow different nodes of a network to
communicate directly with each
other.
 It receives a message (Ethernet
frame) from any device connected to
its input ports and then transmits the
message only to that output port to
which the destination device is
connected.
 One to one connection
 Ensures optimum utilization of
Bandwidth or N/W resources.
LAN SWITCH

NTIPRIT
SWITCH
 Switch Types
• Managed Vs. Unmanaged
• Layer 2 Vs. layer 3 switch
• Multi layer Switch

NTIPRIT
Unmanaged Switch
• In scenarios where the network traffic is light, all that
is required is a way for the data to pass from one
device to another.
• There is no need for prioritizing the packets as all the
traffic will flow unimpeded.
• An unmanaged switch will fill this need without
issues.

NTIPRIT
Managed Switch
• As the number of devices increases, the ability to
ensure that the time-sensitive packets are prioritized
becomes increasingly difficult as more concurrent
streams of data hit the network.
• Another issue that may need to be dealt with is which
devices have access to what portion of the network.

NTIPRIT
Multilayer Switch
• A multilayer switch is a network device that has the
ability to operate at higher layers of the OSI reference
model.
• A multilayer switch can perform the functions of a
switch as well as that of a router at incredibly fast
speeds.
• Multilayer switches became devices that examine
Layer 2 through Layer 7.

NTIPRIT
Hub vs. Switch
HUB
 Broadcast Data Frame to all
nodes connected to it
 Inefficient use of LAN
Bandwidth
 Half Duplex Communication
 Unmanaged
SWITCH
 Frame from source node is
sent only to destination node
 Efficient use of Bandwidth –
Micro segmenting
 Full Duplex Communication
 Can be managed

NTIPRIT
BRIDGE
 A bridge connects a LAN to
another LAN that uses the same
protocol (for example, Ethernet or
token ring).
 Has ports connected to two or
more separate LANs. Packets
received on one port may be re-
transmitted on another port.
 Bridges learn which addresses are
on which network and develop a
learning table so that subsequent
messages can be forwarded to the
right network.
 Operates at Data Link Layer.
 Bridge
LAN1 LAN2

NTIPRIT
ROUTER
 A router is a device or a software in a
computer that determines the next network
point to which a packet should be
forwarded to its destination.
 Allows different networks to communicate
with each other
 A router creates and maintain a table of the
available routes and their conditions and
uses this information along with distance
and cost algorithms to determine the best
route for a given packet.
 A packet will travel through a number of
network points with routers before arriving
at its destination.

NTIPRIT
SWITCH
Processor
Memory
NIC
NIC
NIC
NIC
NIC
NIC
OUTPUT
PORT
INPUT
PORT
INSIDE THE ROUTER
28

NTIPRIT
ROUTERS
 Edge Router
• Routes data packets between a Backbone Network
and LAN
 Core Router
• Routes data packets Within a Backbone Network
 Gateway Router
 B-router
• Router Combined with Bridge Functionality
 Firewall Router
• Router having Packet Filtering capabilities

NTIPRIT
GATEWAY
 A gateway is a network point ,
similar to router that acts as an
entrance to another network;
 Gateway Connects Networks on
Different Protocols/dissimilar
networks
 Gateway nodes are computers
that control traffic within a
company’s network or at local
internet service provider (ISP)
 Gateway

NTIPRIT
Dynamic vs. Static Routing
 STATIC ROUTING :
Routers forward the arriving Data packets to
predefined output port. The routing table is
manually configured.
 DYANMIC ROUTING :
The Router learns the state of the Network and
continuously update its routing table. For this, it
uses routing protocols.

NTIPRIT
What is the difference between….?
 Bridge: device to interconnect two LANs that use
the SAME logical link control protocol but may
use different medium access control protocols.
 Router: device to interconnect SIMILAR
networks, e.g. similar protocols and workstations
and servers
 Gateway: device to interconnect DISSIMILAR
protocols and servers.

NTIPRIT
SWITCHING
33
• Switching is basically transfer of
information from one point to another
point with some intelligence or control
or
• Establishing a temporary path or
connection between two points or
writing at one point of time and reading
at another point of time.

NTIPRIT
SWITCH
 A switch is a device that channels incoming data from any of multiple
input ports to the specific output port that will take the data toward its
intended destination
 In the traditional circuit-switched telephone network, one or more
switches are used to set up a dedicated though temporary
connection or circuit for an exchange between two or more parties
 On local area network (LAN), a switch determines, from the physical
device (Media Access Control or MAC) address in each incoming
message frame, which output port to forward it
 In a wide area packet-switched network such as the Internet, a
switch determines from the IP address in each packet which output
port to use for the next part of its trip to the intended destination

NTIPRIT
Packet Switching
 A digital network technology that breaks up a message (Bit Stream)
into fixed size packets for transmission
 Each packet is then transmitted individually and can even follow
different routes to its destination.
 Once all the packets forming a message arrive at the destination,
they are recompiled into the original message.
 Packets of different messages share the communication channel
 When traversing network switches, routers and other network
nodes, packets are buffered and queued, resulting in variable delay
and throughput depending on the traffic load in the network.

NTIPRIT
AN END TO END CHANNEL WITH MULTIPLE PATHS
THROUGH THE INTERMEDIATE NODES
36

NTIPRIT
Packet Switching :
Illustration
1
2
4
3
2
2
4
1
3
4
1
1 1
31
4
4 3 2 1
2 1
1432
3
1
12
24
2

NTIPRITNTIPRIT
Data traffic is divided into packets.
• Packets travel separately through network
• Packet forwarding based on the header
• Network nodes may store packets temporarily
Destination reconstructs the message
• Best-effort delivery
• Packets may be lost
• Packets may be corrupted
• Packets may be delivered out of order
Each packet contains a header with Source and destination address
38
Packet Switching : features

NTIPRITNTIPRIT
The effectiveness of a data communication system depends on four
fundamental characteristics
Delivery
The system must deliver data to the correct destination.
Accuracy
Accurately- without errors/ alteration/ duplication/ missing
Timeliness
Data delivered late are useless.
•in the same order that they are produced,
•without significant delay.
•This kind of delivery is called Real-time transmission.
Jitter
 Variation in the arrival time of packets. Uneven delay in delivery of
packets may cause data disruption .
.
Fundamental Characteristics

NTIPRIT
Routing vs. Switching
ROUTING
 Routing is the process of
selecting paths in a network
along which to send network
traffic
 Based on Logical (IP) Address
 Forwarding Decision by
Microprocessor
 At Layer 3 (Network layer) of
OSI
SWITCHING
 Switching is one to one data
frame transmission in a LAN
Segment
 Based on Physical (MAC)
address
 Generally Hardwired (ASIC)*
 At Layer 2 (Data Link layer) of
OSI
(* Application Specific Integrated Circuit.: Customized for particular use rather than general purpose.)

NTIPRIT
Advantages:
o Bandwidth used to full
potential.
o Diverse Devices & Networks
can communicate
o Not affected by line failure (re-
diverts signal)
o Availability – do not have to
wait for a direct connection to
become available
o More Robust : Shared
resources & Redundancies
Disadvantages
o Low Throughput
o Under heavy use there can be
a delay
o Data packets can get lost or
become corrupted
o Variable delay : Jitter
o Each packet need header :
Overload
Packet Switching

NTIPRIT
TYPES OF DATA COMMUNICATION
GUIDED
BASED UPON THE KIND OF
COMMUNICATION CHANNEL
UNGUIDED
:waves are guided along a solid medium
path (twisted pair, coaxial cable, and
optical fiber).
:waves are propagated through the
atmosphere and inner/outerspace (satellite,
laser, and wireless transmissions). 42

NTIPRIT
SIMPLEX
BASED UPON THE
DIRECTIONALITY OF DATA
TRANSMISSION
HALF DUPLEX
FULL DUPLEX
43

NTIPRIT
TYPES OF DATA COMMUNICATION: Routing of Packet
ANYCAST
BASED UPON DIRECTION OF DATA
TRANSMISSION
UNICAST
Anycast is a network addressing and routing methodology in which
datagrams from a single sender are routed to the topologically nearest
node in a group of potential receivers all identified by the same
destination address.
Addressing uses a one-to-one association between destination address
and network endpoint: each destination address uniquely identifies a
single receiver endpoint.
44

NTIPRIT
MULTICAST
Multicast is the delivery of a message or information to a
group of destinations, simultaneously in a single
transmission from the source.
Copies are automatically created in other network
elements, such as routers.
45

NTIPRIT
BROADCAST
broadcasting refers to transmitting a packet that will be
received by every device on the network
46

NTIPRIT
Geocast refers to the delivery of information to a group of
destinations in a network identified by their geographical
locations.
 It is a specialized form of multicast addressing used by
some routing protocols for mobile ad hoc networks.
GEOCAST
47

NTIPRIT
CONNECTION
ORIENTED
BASED UPON END TO END
CONNECTION
CONNECTIONLESS
UDP
48

NTIPRIT
Connection Vs. Connectionless
 Connection Oriented
• Requires a session connection (analogous to a phone call) be
established before any data can be sent
• data is delivered in correct order, and signalling overhead is
required during a connection establishment phase
• This Provides Reliable Service
• Implemented at Transport and Data Link layer
• Examples Frame Relay and ATM networks- Data Link
– TCP – Transport layer
– MPLS – Network layer
– Example is IP (Internet Protocol) – Network layer ; UDP –
Transport layer

NTIPRIT
Connection oriented vs. Connectionless
 Connectionless
• Does not require a session connection between sender and
receiver. The sender simply starts sending packets (called
Datagrams) to the destination. (Like sending a Post Card).
• Packets of same message may reach to the end node via different
intermediate node and may reach out of order
• Un-reliable but fast service
– Example is IP (Internet Protocol) – Network layer ; UDP –
Transport layer

NTIPRIT
Types Of Data Communication
SERIAL
PARALLEL
51

NTIPRIT
Serial Transmission
 Data is transmitted, on a single channel, one bit
at a time one after another
Receiver receivedSender
transmitted
101 0 0 1 1 0

NTIPRIT
Receiverreceived
-each bit has it’s own piece of wire along which it travels
- often used to send data to a printer
Parallel Transmission
53
All bits are sent simultaneously
Sendertransmitted
1
0
0
1
1
0
0
1

NTIPRIT
What is MAC Address?!
 Media Access Control (MAC) Address – are the physical
address of any device, e.g. a NIC in a computer on the
network.
 The MAC address has two parts of 3 bytes long.
 The first 3 bytes specify the company that made the NIC
and the second 3 bytes are the serial number of the NIC.

NTIPRITNTIPRIT
Protocol are used for communication between computers
in different computer networks. Protocol achieves:
What is communicated between computers?
How it is communicated?
When it is communicated?
What conformance (bit sequence) between computers?
Protocols

Data Communication Tasks/functions
•Switching •Addressing •Sequencing
•Interfacing •Routing •Flow Control
•Signal Generation •Recovery •Error Feedback
•Synchronization •Formatting •Network MGT
•Exchange
Management
•Security/safety •QoS
•Error Detection &
Correction
•Monitoring
System
Utilization
•N/W
Administration
599/13/2016 Introduction Data Com

NTIPRIT
Circuit Switching
SAS
Direction of transmission
Time Slots as Physical Channels
BCDAD
D
A
B
C
D
BCS
C
B
A

NTIPRIT
Circuit Switching
SAS
Inefficient Utilization of media
___A_
D
A
__S
C
B
A

NTIPRIT
A
BDAD
D
A
B
C
D
B
C
B
A
Virtual Channels
No Physical channel like a Time Slot
Statistical or Asynchronous Multiplexing
Packet Switching
9/13/2016 63

Data communication basics

More Related Content

What's hot

Viewers also liked

Similar to Data communication basics

More from Naveen Jakhar, I.T.S

Recently uploaded

Data communication basics

Editor's Notes