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Network�Fundamentals
Lecture�01:�Introduction�to�
Networks
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
Module�Code�|�Module�Name�|�Lecture�Title�|�Lecturer
NETWORKING�TODAY
• Network�has�no�boundary�and�supports�the�way�we:
ü Communicate
ü Share
ü Work
ü Learn
ü Play
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
NETWORKS
• Networks�of�many�sizes
ü Small�Home�/�Office�Networks
ü Medium�to�Large�Networks
ü World�Wide�Network
• Clients�and�Servers
• Peer-to-Peer
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
COMPONENTS�OF�THE�NETWORK�-�
DEVICES
ü End�devices
ü Intermediate�devices
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
COMPONENTS�OF�THE�NETWORK�
-�MEDIA
• Provide�the�pathway�for�data�transmission
• Interconnect�devices
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
NETWORK�MEDIA
Wireless
Copper�Cables
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
NETWORK�MEDIA�CONT.
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
NETWORK�SYMBOLS
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
TOPOLOGY�DIAGRAMS
• Physical� topology� diagrams� -� Identify� the� physical� location� of� intermediary�
devices�and�cable�installation.
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
TOPOLOGY�DIAGRAMS�CONT.
• Logical�topology�diagrams�-�Identify�devices,�ports,�and�addressing�scheme.�
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
NETWORK�TYPES
• Local�Area�Network�(LAN)
• Wide�Area�Network�(WAN)
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
NETWORK�TYPES�CONT.
• Intranets
• Extranets
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
CONVERGED�NETWORKS
• Traditional�Networks
• The�Converging�Networks
Capable�of�delivering�data,�voice,�and�video�over�the�same�network�
infrastructure
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
RELIABLE�NETWORKS
• Four�Basic�Characteristics�of�Network�Architecture
ü Fault�Tolerance
ü Scalability
ü Quality�of�Service�(QoS)
ü Security
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
ELEMENTS�OF�
COMMUNICATION
ü Message�source
ü The�channel
ü Message�destination
ü Rules
• Common�language�and�grammar
• Speed�and�timing�of�delivery
• Confirmation�or�acknowledgment�requirements
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
MESSAGE�DELIVERY�
OPTIONS
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
• A�reference�model�defines�how�applications�can�communicate�over�a�network�
(the�full�process)
• A�layered�reference�model�divides�the�full�process�into�specific�related�
groups of�actions�at�each�layer
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
• Provides�a�common�language�for�vendors
• Fosters�competition�between�vendors
• Changes�in�one�layer�do�not�affect�other�layers
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
• Open�standards�encourage�competition�and�innovation.�
• Guarantee�that�no�single�company’s�product�can�
monopolize�the�market
• Standards�organizations�include:
• The�Internet�Society�(ISOC)�
• The�Internet�Architecture�Board�(IAB)
• The�Internet�Engineering�Task�Force�(IETF)
• The�Institute�of�Electrical�and�Electronics�Engineers�
(IEEE)
• The�International�Organization�for�Standardization�(ISO)
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
• Define�a�common�format�and�a�set�of�rules�for�the�data�
communication
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
IE1020|�Network�Fundamentals�|�Communicating�Over�Networks|�Dr.�
Network�Fundamentals�
IE1020
Lecture�02:�ISO�-�OSI�
reference�model
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
Module�Code�|�Module�Name�|�Lecture�Title�|�Lecturer
ISO�-�OSI�REFERENCE�
MODEL
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
UPPER�LAYERS
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
APPLICATION�LAYER
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
APPLICATION�LAYER
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
APPLICATION�LAYER�CONT.
• Closest�to�the�end�user.
• Enables�the�user�(human�or�software)�to�access�the�network.�
• Provides�user�interfaces�and�support�shared,�distributed�network�services.
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
APPLICATION�LAYER�
SERVICES
§ Web�and�e-mail�services
§ IP�addressing�services
§ File�sharing�services
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
APPLICATION�LAYER�
SERVICES�CONT.
DNS�services
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
APPLICATION�LAYER�
SERVICES�CONT.
DHCP�services
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
APPLICATION�LAYER�
PROTOCOLS
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
APPLICATION�LAYER�
SOFTWARE
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
APPLICATION�LAYER�
SOFTWARE�CONT.
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
APPLICATION�LAYER�
SOFTWARE�CONT.
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
APPLICATION�LAYER�
SOFTWARE�CONT.
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
PRESENTATION�LAYER
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
PRESENTATION�LAYER
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
SESSION�LAYER
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
SESSION�LAYER
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
SESSION�LAYER�CONT.
• Creates� and� maintains� sessions� (dialogs)� between� source� and� destination�
applications.
• A�session�is�a�series�of�interactions�between�the�source�and�destination�applications�
that�occur�during�the�span�of�a�single�connection.�
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
SESSION�LAYER�CONT.
• Session�layer�handles�the�exchange�of�information�to�
ü
initiate�dialog
ü
keep�them�active�(synchronize)
ü
restart�sessions�that�are�disrupted�or�idle
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
SESSION�LAYER�CONT.
• A�computer�can�establish�multiple�sessions�with�several�other�
computers
Yaho
o
AOL
ESP
N
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
SESSION�LAYER�CONT.
• Two�computers�can�establish�multiple�sessions
mail
music
news
IE1020|�Network�Fundamentals�|�ISO�-�OSI�reference�model|�Dr.�Windhya�
Network Fundamentals
Lecture 03: Transport Layer
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
Transport Layer
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
Transport Layer Responsibilities
Tracking�conversations�(Processes)
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
Transport Layer Responsibilities Cont.
Tracking�conversations�(Processes):�port�
addresses
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
Transport Layer Responsibilities Cont.
Tracking�conversations:�port�addresses
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
Transport Layer Responsibilities Cont.
Segmentation
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
Transport Layer Responsibilities Cont.
Segmentation
Application�Layer
Transport�Layer
Segmentation
MSS
Header
Network�Layer
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
Transport Layer Protocols
Media�Independence
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
Transport Layer Protocols
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
Transport Layer Protocols Cont.
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
Transmission Control
Protocol (TCP)
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
TCP Features
• Connection�Oriented
ü Connection�establishment
Stateful
ü Data�transfer
ü Connection�termination
• Guaranteed�delivery�
Acknowledgements,�Retransmission
• Same-Order�delivery�(correct-order)
Reliable
• Flow�control
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
TCP: Connection Oriented
Client
Connection�
establishment
SYN
1
time
ACK
Server
2
SYN
ACK
3
4
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
TCP: Connection Oriented Cont.
Client
Connection�
establishment
SYN
1
time
3-Way�
Handsh
ake
Server
ACK +
SYN
ACK
2
3
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
TCP: Connection Oriented Cont.
Data�transfer
Client
Data
Server
ACK
• TCP�is�a�reliable�protocol.
• TCP� sends� an� Acknowledgement�
Data
(ACK)� for� each� segment� of� received�
data.
ACK
Data
ACK
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
TCP: Connection Oriented Cont.
Data�transfer�cont.
• Piggybacking:�Sending�(Data�and�ACK)�or�
(SYN�and�ACK)�together.�
Client
Server
Data
TIME
Data, ACK
Data, ACK
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
TCP: Connection Oriented Cont.
Connection�termination
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
TCP Guaranteed Delivery
Acknowledgments�and
Retransmission
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
TCP Same Order Delivery
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
TCP: Data transfer
Server
Client
• Data�is�transferred�as�Segments
SN=100
• Each� segment� is� given� an� identification�
called�a�Sequence�Number
• Each�
acknowledgement�
Data=200 bytes
ACK
is�
given�
an�
AN=300
identification�called�an�Acknowledgement�
Number
• Acknowledgement�Number
ü
Next�expected�segment’s�sequence�number
(Received�segment’s�sequence� number�+� No.� of�bytes�in�the�
segment)
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
TCP: Data transfer Cont.
Server
Client
SN=100
• Sequence�Number�
Data=200 bytes
ACK
ü ����Calculated�based�on�the�received�segment
AN=300
(Received�segment’s�Acknowledgement�number)
SN=300
Data=400 bytes
ACK
AN=700
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
TCP: Data transfer Cont.
Server
Client
• Sequence�Number�
SN=100
Data=200 bytes
ü ����Calculated�based�on�the�received�segment
(Received�segment’s�Acknowledgement�number)
SN=300
Data=400 bytes
OR
ü ����Calculated� based� on� the� previously� sent�
segment
(Previously�� Sent� segment’s� sequence�number� +� No.� of�
ACK
AN=700
bytes�in�the�segment)
ISN:�Very�1st�segments'�sequence�number,�
Randomly�generated
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
TCP States
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
TCP States Cont.
CLIE
NT
SERV
ER
CLOSE
D
Recv:�
SYN
Send:�
SYN,ACK
SYN_RCV
D
Recv:�
ACK
Recv:�
SYN,ACK
ESTABLISH
ED
Send:�
FIN
FIN_WAIT
_1
Recv:�
ACK
FIN_WAIT
_2
LISTE
N
Recv:�
FIN
Send:�
ACK
Send:�
SYN
2MSL�
timeout
TIME_WAI
T
SYN_SE
NT
Send:�
ACK
Recv:�
FIN
CLOSE_W
Send:�
AIT
ACK
Send:�FIN
Recv:�
LAST_AC ACK
K
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
TCP Establishing a Session
CLIEN
T
CLOS
ED
SYN_SE
NT
ESTABLISHE
D
SERV
ER
SYN
CLOSE
D
LISTE
N
SYN_RC
VD
SYN,AC
K
ACK
ESTABLIS
HED
Data
ACK
FIN_WAIT_
1
FIN_WAIT_
2
2MS
L
TIME_WAI
T
CLOS
ED
FIN
CLOSE_WAI
T
ACK
FIN
ACK
LAST_A
CK
CLOSE
D
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
TCP Header
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
TCP Header Cont.
Header�Length�(HLEN)
• Indicates� the� length� of� the� TCP� header� by� number� of� 4-byte�
words�in�the�header,�
• If�the�header�is�20�bytes�(minimum�length�of�TCP�header),�
HLEN�=�20/�4
�����������=�5��(0100b)
• If�the�header�the�60�bytes�(maximum�length�of�TCP�header)
HLEN�=�60/�4
If�the�header�is�60�bytes�(maximum�length�of�TCP�
=�20�bytes�(standard�header)�+�40�bytes�(options
�����������=�15�(1111b)
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
TCP Header Cont.
TCP�Control�bits
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
TCP Header Cont.
Window�Size:�TCP�Flow�
Control
TX�
Buffer
(500)
Read�Data
Serv
er
RX�
Clie
Buffer nt
(500)
SN=100
200 500 300
TX�
Buffer
(700)
RX�
Buffer
(700)
Data=200 bytes
200 700 500
ACK
AN=300
300
SN=300
200
Sliding�
Window
Data=300 bytes
300
400
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
TCP Header Cont.
Urgent�Pointer
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
TCP Header Cont.
Options
• If�the�header�is�60�bytes�(maximum�length�of�TCP�header)
=�20�bytes�(standard�header)�+�40�bytes�(options�bytes)
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
Applications that Use TCP
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
User Datagram Protocol
(UDP)
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
UDP
• UDP�Features
• Simple�and�fast
• Connectionless
• Stateless
• Best�effort�delivery:�Unreliable
• UDP�Header
• The� pieces� of� communication� in� UDP� are� called�
Datagrams.
• UDP�adds�only�8�bytes�of�overhead�(header�is�8�bytes)
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
UDP Header
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
UDP – Low Overhead vs Reliability
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
UDP Datagram Reassembly
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
Applications that Use UDP
IE1020|�Network�Fundamentals�|�Lecture�03|�Ms.�Pipuni�Wijesiri
d
n
E
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T
93
94
Network Fundamentals
Lecture 04: Network Layer
IE1020|�Network�Fundamentals�|�Lecture�04|�Ms.�Pipuni�Wijesiri
Network Layer
IE1020|�Network�Fundamentals�|�Lecture�04|�Ms.�Pipuni�Wijesiri
Network Layer Features
§ Addressing�
end�
devices
§ Encapsulation
§ Routing
IE1020|�Network�Fundamentals�|�Lecture�04|�Ms.�Pipuni�Wijesiri
Network Layer Protocols
IE1020|�Network�Fundamentals�|�Lecture�04|�Ms.�Pipuni�Wijesiri
Internet Protocol (IP)
Connectionless�
Communication
IE1020|�Network�Fundamentals�|�Lecture�04|�Ms.�Pipuni�Wijesiri
IP Cont.
Best�Effort�Delivery
IE1020|�Network�Fundamentals�|�Lecture�04|�Ms.�Pipuni�Wijesiri
IP cont.
Media�Independence
IE1020|�Network�Fundamentals�|�Lecture�04|�Ms.�Pipuni�Wijesiri
IP Packets
IP�header�for�TCP�
segments
IE1020|�Network�Fundamentals�|�Lecture�04|�Ms.�Pipuni�Wijesiri
IPv4 Packet Header
*
*
*
*
*
IE1020|�Network�Fundamentals�|�Lecture�04|�Ms.�Pipuni�Wijesiri
IPv4 Packet Header Cont.
IHL�(IP�Header�Length)
• �Indicates�the�length�of�the�IP�header�by�number�of�4-byte�
words�in�the�header�(Similar�to�HLEN�in�TCP�header)
• If�the�header�is�20�bytes�(minimum�length�of�IP�header),�
IHL�����=�20/�4
�����������=�5��(0100b)
• If�the�header�the�60�bytes�(maximum�length�of�IP�header)
IHL����=�60/�4
�����������=�15�(1111b)
IP�Heade
IE1020|�Network�Fundamentals�|�Lecture�04|�Ms.�Pipuni�Wijesiri
IPv4 Packet Header Cont.
Type�of�service�(ToS)�field
IP�Header
IE1020|�Network�Fundamentals�|�Lecture�04|�Ms.�Pipuni�Wijesiri
IPv4 Packet Header Cont.
Packet�Length
• Indicates�the�total�length�of�the�IP�Packet
• Total�Length�=�Header�Length�+�Data�Length
• Maximum�Total�Length�is�65535�bytes
• Maximum�Data�Length�?
IP�Heade
IE1020|�Network�Fundamentals�|�Lecture�04|�Ms.�Pipuni�Wijesiri
IPv4 Packet Header Cont.
Fragmentation
Transport�Layer
3000
Network�Layer
3000
F1
MTU
F2
1480
Fragmentation
F3
1480
40
(For�Ethernet�=�1500�bytes)
Header
(20�bytes)
DataLink�Layer
(Ethernet)
IE1020|�Network�Fundamentals�|�Lecture�04|�Ms.�Pipuni�Wijesiri
IPv4 Packet Header Cont.
Fragmentation
Transport�Layer
3000
Network�Layer
3000
F1
F2
Fragmentation
F3
MTU
DataLink�Layer
(Ethernet)
DF
Reserved
MF
• DF:�Do�not�Fragment
• MF:�More�Fragments
IE1020|�Network�Fundamentals�|�Lecture�04|�Ms.�Pipuni�Wijesiri
IPv4 Packet Header Cont.
Fragmentation
Transport�Layer
3000
Network�Layer
3000
Fragmentation
F3
F1
F2
ID
x
x
x
DF
0
0
0
MF
1
1
0
MTU
DataLink�Layer
(Ethernet)
FO
IE1020|�Network�Fundamentals�|�Lecture�04|�Ms.�Pipuni�Wijesiri
IPv4 Packet Header Cont.
Fragmentation
Transport�Layer
3000
Network�Layer
3000
F1
1480
MTU
DataLink�Layer
(Ethernet)
F2
0th
/
8
FO
0
Fragmentation
F3
40
1480
1479th 1480th 2959th 2960th2999
/
/
8
8
th
185
270
IP�Heade
IE1020|�Network�Fundamentals�|�Lecture�04|�Ms.�Pipuni�Wijesiri
IPv4 Packet Header Cont.
Time�To�Live�(TTL)
• When�a�packet�of�information�is�created�and�sent�out�across�the�Internet,�there�
is�a�risk�that�it�will�continue�to�pass�from�router�to�router�indefinitely�(looping).�
• To�mitigate�loops,�packets�are�designed�with�an�expiration�called�a�time-to-live�
or�hop�limit.
TTL�=�
15
TTL�=�
16
TTL�=�
14
TTL�=�
15
TTL�=�
13
TTL�=�
14
TTL�=�
1
TTL�=�
2
TTL�
=�0
TTL�
=�1
DRO
P
IP�Heade
IE1020|�Network�Fundamentals�|�Lecture�04|�Ms.�Pipuni�Wijesiri
d
n
E
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e
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T
112
113
Network Fundamentals
Lecture 05: Addressing
IE1020|�Network�Fundamentals�|�Lecture�05|�Ms.�Pipuni�Wijesiri
Network Layer Address: IP Address
• There�are�two�major�versions�of�IP�addresses
IPv4
IP�Addresses
IPv6
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Network Layer Address: IP Address (Cont.)
• IP�version�4�(IPv4)�address�is�32�bits�long�(i.e.�4�bytes)
• IP�version�6�(IPv6)�address�is�128�bits�long�(i.e.�16�bytes)
IPv4
IPv6
32-bit IP Address
128-bit IP Address
4.3 billion addresses
Addresses must be reused and masked
7.9x1028 addresses
Every device can have a Unique address
Numeric dotted-decimal notation
192.168.5.18
Alphanumeric hexadecimal notation
50b2:6400:0000:0000:6c3a:b17d:0000:10a9
(Simplified -50b2:6400::6c3a:b17d:0:10a9)
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IP Version 4 (IPv4)
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Classful Addressing
• When IP addressing was first introduced, All IPv4 addresses were
divided into 5 classes.
Class
Usage
Class A
General Purpose
Class B
General Purpose
Class C
General Purpose
Class D
Multicasting
Class E
Reserved for future use
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Finding the Class in Binary Notation
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Finding the Class in Decimal Notation
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Network ID (Net ID) and Host ID
• Each IP address consist of two parts,
Network ID
Host ID
Common in all the hosts within that organization
Unique to each host
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Network ID (Net ID) and Host ID (Cont.)
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Masking Concept
• Each� LAN� is� owned� by� a� particular� organization,� and� the� net� ID� is� what�
differentiates�one�LAN�from�another�in�Internet�terms.�
• �Finding�the�net�ID�is�extremely�important�
since� net� ID� is� used� by� routers� to� route� the� packets� from� one� LAN� to�
another�LAN�over�the�Internet�
• When�we�look�at�a�classful�IP�address,�we�can�easily�say�to�which�class�that�IP�
address�is�belonging�to�and�there�by�what�is�the�net�ID�of�that�IP�address.
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Masking Concept (Cont.)
• Default�Masks
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Masking Concept (Cont.)
• Although� we� humans� can� easily� interpret� the� net� ID� of� a� given� classful� IP�
address,�how�does�a�router�calculate�the�net�ID?
• For�this�we�use�the�concept�of�masking
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Special IPv4 Addresses
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Direct Broadcast Address (Broadcast Address)
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Loopback Address
ü The most widely
used loopback
address is 127.0.0.1
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IPv4 – Exercise 1
For�following�addresses,�find�the�
• Net�mask
• Network�address
• Broadcast�address
• 1st�usable�host�ip�address
• Last�usable�host�ip�address
Ø
Ø
Ø
Ø
Ø
23.56.7.91
72.87.34.10
130.10.1.21
200.50.60.1
198.1.1.1
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IPv4 – Exercise 1 (Answer)
198.1.1.1�–�Class�C
�������11000110�.�00000001�.�00000001�.�00000001
����
�Net�ID
����������Host�ID
Net�Mask������11111111�.�11111111�.�11111111�.�00000000���������
255.255.255.0
��������Net�ID:�All�‘1’s
���Host�ID:�All�‘0’s
Network���������11000110�.�00000001�.�00000001�.�00000000��������
198.1.1.0
Address
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��������Net�ID:�As�it�is
���Host�ID:�All�‘0’s
IPv4 – Exercise 1 (Answer)(Cont.)
Broadcast��������������11000110.�00000001.�00000001.�
11111111���������198.1.1.255
Address
��������Net�ID:�As�it�is
���Host�ID:�All�‘1’s
1st�Usable������11000110�.�00000001�.�00000001�.�00000001��������
198.1.1.1
IP�Address
��������Net�ID:�As�it�is
combination�
(One�after�All�‘0’s)
���Host�ID:�Second�
Last�Usable���11000110�.�00000001�.�00000001�.�11111110��������
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Public addresses vs Private Addresses
• Any�device�that�connects�directly�into�Internet�must�have�a�public�IP�address
• A�private�IP�addresses�can�be�used�within�a�private�network
• A� private� IP� address� is� mapped� to� a� public� IP� address,� when� the� machine� has� to�
access�the�Internet
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IPv4 Private Address Ranges
• Following�ranges�are�reserved�to�be�used�in�Local�Area�Networks�for�private�
addresses.
.255
• Remember:� You� cannot� use� these� ranges� for� machines/interfaces� that� are�
directly�connected�to�Internet.
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Network address translation (NAT)
• NAT�(Network�Address�Translation)�Maps�Private�IPs�to�
Public�IPs
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Network address translation (NAT) Cont.
• Static�NAT�:�Maps�unique�Private�IP�to�a�unique�Public�IP�
• Dynamic�NAT�:�Maps�Multiple�Private�IPs�to�a�Pool�of�Public�IPs�
• Port�Address�Translation�(PAT)�:�Maps�a�Public�IP�and�a�Port�Number�to�
a�service�in�Private�IP
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Problems with Classful Addressing
• Class�A�and�B�are�too�large�for�typical�organizations�and�many�IP�addresses�will�
not�be�used�and�wasted.
• Class�C�is�not�enough�for�most�organizations�resulting�the�reservation�of�at�least�
a�Class�B�address�range�for�the�organization.
• The� end� result� is� that,� the� available� IP� addresses� are� depleting� at� an� alarming�
rate�and�soon�there�will�be�no�more�IP�addresses.
Solutions:
• Short�Term:�Classless�Addressing�(FLSM/VLSM)
• Long�Term:�IPv6
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Classless Addressing (Subnets)
• Suppose� you� are� given� a� network� address� 172.16.0.0� for� your�
network.
Class B
172.16.0.0 / 16
10010110.01100100.00000000.00000000
Net�ID
• You�
have�
three�
������������Host�ID
departments:�
Finance,�
Production�
and�
Administration.�
• To� enhance� efficiency� of� network,� you� want� divide� network� into�
three�networks.
• But�you�cannot�get�another�two�network�addresses.�
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Classless Addressing (Subnets) Cont.
• Now�the�IP�address�is�divided�into�three�parts.
Net�ID�����Subnet�ID�����Host�ID
• The�original�Net�ID�number�of�bits�is�not�changed.
• Part�of��“Host�ID”�is�allocated�as�the�“Subnet�ID”.
• In�the�above�example�172.16�(i.e.�first�16�bits)�are�not�changed.�
10101100.0001000.00000000.00000000
��������
�����������Net�ID
• In�the�remaining�16�bits�the�most�significant�bits�are�allocated�as�Subnet�
ID.�
10101100.00010000.00000000.00000000
����������������Net�ID������������Subnet�ID�+�Host�ID
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Classless Addressing (Subnets) Cont.
• Since� we� need� three� subnets� at� least� two� bits� are�
required�for�Subnet�ID�(22�=�4)
00,�01,�10�and�11
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Classless Addressing (Subnets) Cont.
• Therefore�the�subnets�can�be�written�as
Subnet�0
10101100.00010000.00000000.00000000
Subnet�1
10101100.00010000.01000000.00000000
Subnet�2
10101100.00010000.10000000.00000000
Subnet�3
10101100.00010000.11000000.00000000
• In�dotted�decimal,�it�can�be�written�as,
Subnet�0�address
172.16.0.0��/18
Subnet�1�address
172.16.64.0��/18
Subnet�2�address
172.16.128.0��/18
Subnet�3�address
172.16.192.0��/18
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Classless Addressing (Subnets) Cont.
§ For�the�above�example�the�Finance,�Production�and�Administration�
Sections�can�be�put�to�three�subnets�as�follows.
172.16.0.0/ 18
• Consider� the� hosts� in� subnet�
172.16.64.0��
• The� IP� addresses� can� be� given�
172.16.64.0/ 18
as
ü 172.16.64.1
ü 172.16.64.2
172.16.128.0/ 18
ü 172.16.64.3�
ü 172.16.64.4�etc.
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Classless Addressing (Subnets) Cont.
172.16.64.0�/�18
�������10101100�.�00010000�.�01000000�.�00000000
�����Net�ID����������Subnet�ID
�Host�ID
Subnet����������11111111�.�11111111�.�11000000�.�00000000���������
255.255.192.0
Mask
�����������������Net�ID:�All�‘1’s����������Subnet�ID
‘0’s
������������All�‘1’s
����Host�ID:�All�
Network�������10101100�.�00010000.�01000000�.�00000000���������
172.16.64.0/�18
Address
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Classless Addressing (Subnets) cont.
Broadcast�������10101100�.�00010000.�01111111�.�11111111���������
172.16.127.255
Address
�����������������Net�ID:�As�it�is����������Subnet�ID
‘1’s
������������As�it�is
����Host�ID:�All�
1st�Usable�������10101100�.�00010000.�01000000�.�00000001���������
172.16.64.1/�18
Address
�����������������Net�ID:�As�it�is����������Subnet�ID
Second�combination�
(One�after�All�‘0’s)
����Host�ID:�
�As�it�is�
Last�Usable����10101100�.�00010000.�01111111�.�11111110����
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IPv4 – Exercise 2
• If�one�of�the�addresses�in�a�subnet�is�196.88.10.12/28,
• What�is�the�network�address?
• What�is�the�broadcast�address?
• What�is�the�first�host�address?
• What�is�the�last�host�address?
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IPv4 – Exercise 3
• If�one�of�the�addresses�is�190.87.140.202/29,
• What�is�the�network�address?
• What�is�the�broadcast�address?
• What�is�the�first�host�address?
• What�is�the�last�host�address?
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IPv4 – Exercise 4
• What� is� the� first� host� address� in� the� block� if� one� of� the�
addresses�is�
ü 167.199.170.82/27
ü 140.120.84.24/20
• Find� the� number� of� host� addresses� in� the� block� if� one� of� the�
addresses�is�
ü 140.120.84.24/20
ü 140.120.84.24/20
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Classless Addressing (Subnets) Cont.
Subnetting�Based�on�Network�Requirements
• The�number�of�subnet�addresses�required�for�each�network�
• Consider�the�number�of�bits�for�subnet�ID.
Subnetting�Based�on�Host�Requirements
• The�number�of�host�addresses�required�for�each�network�(or�
each�subnet)
• Consider�the�number�of�bits�for�host�ID.
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Fixed Length Subnet Mask (FLSM)
• Creates�all�subnets�with�the�same�size�(equal�number�of�hosts)
Ex:�172.16.0.0�/18
172.16.64.0�/18
172.16.128.0�/18
214�–�2�hosts�in�each�subnet
172.16.192.0�/18
v Not�very�flexible.
v Results�in�wasted�addresses.�
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Fixed Length Subnet Mask (FLSM) Cont.
Problem
ü Consider� a� traditional� Class� C� address� 192.168.1.0� and�
an�organization�with�four�sections:�
• the�call�center�with�50�hosts
• the�data�center�with�75�hosts
With�FLSM,
• the�operations�floor�with�25�hosts
• the�executive�floor�with�20�hosts
192.168.1.000000
00
26�–�2�hosts�
192.168.1.0��/26 (62)
192.168.1.64�/26�in�each�
192.168.1.128�/26
subnet
192.168.1.192�/26
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Variable Length Subnet Mask (VLSM)
Solution
ü Variable�Length�Subnet�Mask�(VLSM)
• Lets�begin�with�summarizing�requirements:
Subnet
Required�IPs
Required�
bits
Reason
Call�center
50
6
(26�–�2�>�50)
Data�center
75
7
(27�–�2�>�75)
Operations
25
5
(25�–�2�>�25)
Executive
20
5
(25�–�2�>�20)
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Variable Length Subnet Mask (VLSM) Cont.
• Next,�sort�the�table�according�to�the�Required�bits�(highest�
to�lowest)
Subnet
Required�IPs
Required�
bits
Reason
Data�center
75
7
(27�–�2�>�75)
Call�center
50
6
(26�–�2�>�50)
Operations
25
5
(25�–�2�>�25)
Executive
20
5
(25�–�2�>�20)
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Variable Length Subnet Mask (VLSM) Cont.
• We�are�going�to�create�subnets�according�to�the�number�of�
hosts�required�
-�to�minimize�the�wasting�of�IP�addresses
• The� process� starts� from� largest� number� of� hosts� required�
and�continue�in�the�descending�order
• Therefore,�we�start�with�the�requirement�of�Data�center�(75�
hosts)
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Variable Length Subnet Mask (VLSM) Cont.
• To� get� 75� IP� addresses� for� data� center,� we� allocate� 7� hosts�
bits
• We�have�1�subnet�bit
�
192.168.1.00000000
192.168.1.10000000
192.168.1.0�
/25
192.168.1.128�
/25
27�–�2�hosts�
(126)
�in�each�
subnet
• One�of�the�newly�created�subnet�(first�subnet)�is�allocated�for�
data�center
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Variable Length Subnet Mask (VLSM) Cont.
• The� remaining� subnet� (192.168.1.128� /25)� is� used� for� further�
subnetting
• The�second�requirement�is�call�center�with�50�hosts
• To�get�50�IP�addresses�for�call�center,�we�allocate��6�hosts�bits
6�–�2�hosts�
• We� have� 1� more� subnet� bit� (all�192.168.1.128�
together� we� 2have�
2� subnet� bits�
now)
�192.168.1.10000000
/26
192.168.1.192�
/26
(62)
�in�each�
subnet
�192.168.1.11000000
• One�of�the�newly�created�subnet�(first�subnet)�is�allocated�for�call�
center
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Variable Length Subnet Mask (VLSM) Cont.
• The� remaining� subnet� (192.168.1.192� /26)� is� used� for�
further�subnetting
• The�third�requirement�is�operations�with�25�hosts
• To� get� 25� IP� addresses� for� call� center,� we� allocate� � 5� hosts�
192.168.1.192� 25�–�2�hosts�
bits
/27
(30)
192.168.1.224� �in�each�
• We� have� 1� more� subnet� bit� (all�together�
we�
have� 3� subnet�
/27
subnet
bits�now)
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�192.168.1.11000000
Variable Length Subnet Mask (VLSM) Cont.
• The�newly�generated�subnets�can�be�allocated�as�follows:�
operations�group:�192.168.1.192/27
executives�group:�192.168.1.224/27
• As�we�are�not�wasting�IP�addresses�
and�further�subnetting�will�not�be�helpful,�
we�can�stop�the�subnetting�process
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Variable Length Subnet Mask (VLSM) Cont.
ü The�data�center�with�75�hosts
192.168.1.0/25
ü The�call�center�with�50�hosts
192.168.1.128/26
ü The�operations�floor�with�25�hosts
192.168.1.192/27
ü The�executive�floor�with�20�hosts
192.168.1.224/27
IE1020|�Network�Fundamentals�|�Lecture�05|�Ms.�Pipuni�Wijesiri
d
n
E
�
e
h
T
158
159
Network Fundamentals
Lecture 06: IPv6 Addressing
IE1020|�Network�Fundamentals�|�Lecture�06|�Ms.�
Limitations of IPv4
Scarcity�of�IPv4�Addresses
• The�IPv4�addressing�system�uses�32-bit�address�space
• 32-bit�address�space�allows�only�232�IPv4�addresses
Configuration
• IPv4�must�be�configured,�either�manually�or�through�the�DHCP
• Limited�support�for�security
Use�of�IPsec�is�optional
• Limited�support�for�Quality�of�Service�(QoS)
Use�of�ToS�bits�in�header
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IPv6
Huge�address�space
§ IPv6� addresses� are� 128� bits� long,� creating� an� address� space� with� 2128� poss
addresses.
Automatic�configuration�
§ IPv6�hosts�can�automatically�configure�IPv6�addresses,�even�in�the�absence�of�a�DH
§ Provide�support�for�security�with�IPsec�
and�for�Quality�of�Service�(QoS)�with�prioritized�delivery
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IPv4 and IPv6 Coexistence
The�migration�techniques�can�be�divided�into�three�categories:�
ü Dual-stack
ü Tunneling
ü Translation
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Dual-stack
• Allows�IPv4� and� IPv6� to� coexist�
on�the�same�network.�
• Devices�run�both�IPv4�and�IPv6�
protocol�stacks�simultaneously.
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Tunneling
• A�method�of�transporting�
an�IPv6�packet�over�an�
IPv4�network.�
• The�IPv6�packet�is�
encapsulated�inside�an�
IPv4�packet.
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Translation
• The� Network� Address� Translation� 64� (NAT64)� allows� IPv6-enabled� devices� to�
communicate�with�IPv4-enabled�devices�using�a�translation�technique
• An�IPv6�packet�is�translated�to�an�IPv4�packet,�and�vice�versa.
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IPv6 Address Representation
• 128� bits� in� length� and� written� as� a� string� of� hexadecimal�
values
• 4�bits�represents�a�single�hexadecimal�digit,�
�128�bits�=�32�hexadecimal�digits
•2001:0DB8:0000:1111:0000:0000:0000:0200
•FE80:0000:0000:0000:0123:4567:89AB:CDEF
• Can�be�written�in�either�lowercase�or�uppercase�
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IPv6 Address Representation Cont.
IE1020|�Network�Fundamentals�|�Lecture�06|�Ms.�Pipuni�Wijesiri
IPv6 Address Rules
1: Omitting Leading “0”s
• The�first�rule�to�help�reduce�the�notation�of�IPv6�addresses�is�
any� leading� 0s� (zeros)� in� any� 16-bit� section� (hextet)� can�
be�omitted.
• Ex:
ü 01AB�can�be�represented�as�1AB.
ü 09F0�can�be�represented�as�9F0.
ü 0A00�can�be�represented�as�A00.
ü 00AB�can�be�represented�as�AB.
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IPv6 Address Rules
2: Omitting All “0” Segments
• A�double�colon�(::)�can�replace�any�single,�contiguous�string�
of� one� or� more� 16-bit� segments� (hextets)� consisting� of�
all�0’s.
• Known�as�the�compressed�format.
• Double� colon� (::)� can� only� be� used� once� within� an� address�
otherwise�the�address�will�be�ambiguous.
2001:0DB8::ABCD::1234�(Incorrect�address)
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IPv6 Address Rules
2: Omitting All “0” Segments Cont.
Example�
#1
Example�
#2
IE1020|�Network�Fundamentals�|�Lecture�06|�Ms.�Pipuni�Wijesiri
IPv6 Prefix Length
• IPv6�does�not�use�the�dotted-decimal�subnet�mask�notation
• Prefix� length� indicates� the� network� portion� of� an� IPv6�
address�using�the�following�format:�
• IPv6�address/prefix�length
• Prefix�length�can�range�from�0�to�128
• Typical�prefix�length�is�/64
IE1020|�Network�Fundamentals�|�Lecture�06|�Ms.�Pipuni�Wijesiri
IPv6 Header Format
§
IPv4:� 20� Bytes�
+�Options��
§
IPv6:� 40� Bytes�
+�Next�Header�
(Extension�
Header)
IE1020|�Network�Fundamentals�|�Lecture�06|�Ms.�Pipuni�Wijesiri
IPv6 Header Format Cont.
IE1020|�Network�Fundamentals�|�Lecture�06|�Ms.�Pipuni�Wijesiri
IPv6 Extension Headers
• Routing –�Extended�routing
• Fragmentation –�Fragmentation�and�reassembly
• Authentication –�Integrity�and�authentication�(security)
• Encapsulation –�Confidentiality
• Hop-by-Hop�Option –�Special�options�that�require�hop-by-hop�processing
• Destination� Options –� Optional� information� to� be� examined� by� the�
destination�node
IE1020|�Network�Fundamentals�|�Lecture�06|�Ms.�Pipuni�Wijesiri
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Network Fundamentals
Lecture 07: Routing
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Hosts Sending IP Packets
A�host�can�send�a�packet�to:
• Itself
ü A�host�can�send�a�packet�to�itself,�by�using�the�loopback�interface�address
• Local�host
ü A�host�can�send�a�packet�to�another�host,�on�the�same�local�network
ü The�hosts�share�the�same�network�address
• Remote�host
ü A�host�can�send�a�packet�to�another�host,�on�a�remote�network�
ü The�hosts�do�not�share�the�same�network�address
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Forwarding Packets to a Remote Host
• In� most� situations� we� want� our� devices� to� be� able� to� connect� beyond� the� local�
network�segment
• Devices�that�are�beyond�the�local�network�segment�are�known�as�remote�hosts
• When�a�source�device�sends�a�packet�to�a�remote�destination�device,�
then�the�help�of�routers�and�routing�is�needed�
• Routing�is�the�process�of�identifying�the�best�path�to�a�destination�
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Default Gateway
• The�router�connected�to�the�local�network�segment�is�referred�to�as�the�default�
gateway.
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Default Gateway (Cont.)
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Default Gateway (Cont.)
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Default Gateway (Cont.)
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Routing
• When�a�packet�arrives�at�the�default�gateway�(router),�
the�router�looks�at�its�routing�table�to�determine�where�to�forward�
packets
• Routing�table�is�constructed�by�considering�IP�addresses
Therefore,�routers�work�in�Layer�3
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Routing (Cont.)
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Routing (Cont.)
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Routing Table
• The�routing�table�of�a�router�can�store�information�about:
• Directly�connected�networks
• Remotely�connected�networks
ü Static�routing
ü Special�case:�default�route
ü Dynamic�routing
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Routing Table (Cont.)
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Routing Table (Cont.)
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Routing Table (Cont.)
Directly�connected�networks
• Directly�connected�networks�are�directly�attached�to�one�of�
the�router�interfaces�
• Router�learns�about�directly�connected�networks�
automatically
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Routing Table (Cont.)
Directly�connected�networks�
Cont.
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Routing Table (Cont.)
Remotely�connected�
networks�Cont.
• These�are�networks�connected�to�other�routers�(remote�
networks)
• Routes�to�these�networks�can�be�
• statically�configured�or�
• dynamically�learned�through�dynamic�routing�protocols.
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Routing to Remotely Connected Networks
• Remote�networks�are�added�to�the�routing�table�
ü Static�routing�(configuring�routes�manually)
ü Dynamic�routing�(using�routing�protocols)
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Static Routing
• A�static�route�includes�
ü the�network�address�and�subnet�mask�of�the�remote�network,�
ü along�with�the�IP�address�of�the�next-hop�router�or�exit�interface.�
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Static Routing (Cont.)
Static�routes�should�be�used�when:
• A�network�with�few�routers
• A�network�is�connected�to�the�Internet�only�through�a�single�ISP
�Static�Routing�Advantages
• Minimal�CPU�processing�
• Easier�for�administrator�to�understand
Static�Routing�Disadvantages
• Configuration�is�time-consuming�and�error-prone
• Does�not�scale�well�with�growing�networks
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Dynamic Routing
Use�of�routing�protocols
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Dynamic Routing (Cont.)
• Routing�tables�are�updated�automatically�using�routing�rules�(�protocols�)
• Routing�tables�have
ü Initially:�‘connected’�records�for�directly�connected�networks
ü Next:�add�‘static’�records�for�remote�networks
ü Finally:�add�dynamic�updates�for�remote�networks�(use�of�routing�protocols)
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Routing Protocols
• Routing�Protocols�allow�routers�to�
ü dynamically�advertise�and�learn�routes
ü determine�which�routes�are�available
ü determine�which�are�the�most�efficient�routes�to�a�destination
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Routing Protocols (Cont.)
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Routing Protocols (Cont.)
• An� autonomous� system� (AS)� is� a� collection� of� routers� under� a� common�
administration
ex�:��a�company's�internal�network
• Interior� Gateway� Protocols� (IGP)� are� used� for� intra-autonomous� system�
routing�
(routing�inside�an�autonomous�system)
• Exterior� Gateway� Protocols� (EGP)� are� used� for� inter-autonomous� system�
routing�
(routing�between�autonomous�systems)
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Routing Protocols (Cont.)
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Interior Gateway Protocols (IGP)
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Distance Vector Routing Protocols
• Routes�are�advertised�as�vectors�of�distance�and�direction
• Distance�is�defined�in�terms�of�a�metric�such�as�hop�count�and�
direction�is�simply�the�next-hop�router�or�exit�interface
• Send�periodic�updates�of�their�routing�information
• Use�the�Bellman-Ford�algorithm�for�best�path�selection
• Work�best�in�situations�where:
-�Network�is�simple
-�Administrators�do�not�have�enough�knowledge�to�configure
Ex�:�RIP,�IGRP,�EIGRP�
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
RIP - Routing Information Protocol
• A�simple�interior�gateway�routing�protocol
• Straightforward�implementation�of�Distance�Vector�Routing
• Each�router�advertises�its�distance�vector�every�30�seconds�
(or�whenever�its�routing�table�changes)�to�all�of�its�neighbors
• Maximum�hop�count�is�15,�with�“16”�equal�to�“”
• Routes�are�timeout�(set�to�16)�after�3�minutes�if�they�are�not�updated
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Link State Routing Protocols
• Send� information� about� the� state� of� its� links� to� other� routers� in� the� routing�
domain
• State�of�those�links�include�
ü information�about�the�type�of�network�and�
ü any�neighboring�routers�on�those�networks
• A�link-state�update�only�sent�when�there�is�a�change�in�the�topology
• Use�the�Dijkstra�algorithm�for�best�path�selection
• Work�best�in�situations�where:
-�Network�is�complex�(large�networks)
Ex�:�OSPF,�IS-IS
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Metrics and Routing Protocols
RIP
ü��Hop�count�(best�path�is�chosen�by�the�route�with�the�lowest�hop�count)
IGRP�and�EIGRP
ü Bandwidth,�Delay,�Reliability,�and�Load
ü Best� path� is� chosen� by� the� route� with� the� smallest� composite� metric� value�
calculated�from�these�multiple�parameters�
ü By�default,�only�bandwidth�and�delay�are�used�
IS-IS�and�OSPF
ü Cost�(best�path�is�chosen�by�the�route�with�the�lowest�cost)
ü �Cisco's�implementation�of�OSPF�uses�bandwidth�cost�
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
Dynamic Routing Advantages/Disadvantages
Advantages:
• Administrator�has�less�work�maintaining�the�configuration
• Protocols�automatically�react�to�the�topology�changes
• Configuration�is�less�error-prone
• More�scalable
Disadvantages:
• Router�resources�are�used�(CPU�cycles,�memory�and�link�bandwidth)
• More� administrator� knowledge� is� required� for� configuration,� verification,� and�
troubleshooting
IE1020|�Network�Fundamentals�|�Lecture�07|�Ms.�
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Network Fundamentals
Lecture 08: Data Link Layer
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Data Link Layer
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Data Link Layer (Cont.)
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Data Link Layer (Cont.)
• Supports�the�communication�processes�over�different�medium
• At�each�hop�along�the�path,�an�intermediary�device�-�usually�a�router�–�
ü accepts�frames�from�a�medium,�
ü decapsulates�the�frame,�
ü and� then� forwards� the� packet� in� a� new� frame� appropriate� to� the� medium� of�
that�segment�of�the�physical�network.�
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Data Link Layer (Cont.)
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Data Link Sub-layers
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Data Link Sub-Layers (Cont.)
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Media Access Control
Collision
s
Overhea
d
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Media Access Control (Cont.)
• The�actual�media�access�control�method�used�depends�on�
ü how�the�media�is�shared
ü topology
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Media Access Control (Cont.)
Methods:�Shared�media
ü Controlled�access
ü Contention-based�access
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Media Access Control (Cont.)
Shared�media:�controlled�access
• Network� devices� take� turns,� in� sequence,� to� access� the�
medium
• Each�device�has�its�own�time�to�use�the�medium
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Media Access Control (Cont.)
Shared�media:�Contention-based�access�
• Allow�any�device�to�try�to�access�the�medium�whenever�it�has�data�to�send.
• To�prevent�collision,�device�needs�to� first�detect�if�the�media�is�already�carrying�a�
signal.
(Ex:�Use�CSMA/CD�or�CSMA/CA)
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Media Access Control (Cont.)
Carrier�Sense�Multiple�Access/Collision�Detection�
(CSMA/CD)
• The�device�monitors�the�media�for�the�presence�of�a�data�signal�
ü If�a�data�signal�is�absent,�indicating�that�the�media�is�free,
then�the�device�transmits�the�data
ü If�a�data�signal�is�present,�indicating�that�another�device�was�transmitting�at�
the�same�time,
the�device�stop�sending�and�try�again�later
• Ethernet�uses�this�method
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Media Access Control (Cont.)
Carrier�Sense�Multiple�Access/Collision�avoidance�
(CSMA/CA)
• The�device�examines�the�media�for�the�presence�of�a�data�signal
ü If�the�media�is�free,�
the�device�sends�a�notification�across�the�media�of�its�intent�to�use�it�
ü Then�the�device�then�sends�the�data
• IEEE�802.11�wireless�networking�technologies�use�this�method
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Media Access Control (Cont.)
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Media Access Control (Cont.)
Non�Shared�media
Half�
Duplex
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Media Access Control (Cont.)
Non�Shared�media
Full�
Duplex
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Media Access Control (Cont.)
Topologies
Controlled�access:�Token�
Passing
Contention�base�
access
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Data Link Layer Address: MAC Address
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Data Link Layer Address: MAC Address (Cont.)
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Data Link Layer Standards
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Data Link Layer Protocols
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Data Link Layer Frame: General
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Data Link Layer Frame: LANs
• Family� of� networking� technologies� that� are� defined� in� the� IEEE� 802.2� and�
802.3�standards
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Ethernet Using Hubs
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Ethernet Using Switches
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Ethernet Using Switches (Cont.)
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Switch MAC Address Learning Process
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Switch Frame Forwarding Methods
• Store-And-Forward�
• Cut-Through�
• Fast-forward�switching
ü Lowest�level�of�latency�
ü Immediately�forwards�a�packet�after�reading�the�destination�address
• Fragment-free�switching
ü Switch�stores�the�first�64�bytes�of�the�frame�before�forwarding
ü Most�network�errors�and�collisions�occur�during�the�first�64�bytes
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Switch Port Settings
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Address Resolution Protocol (ARP)
192.168.10.2
PC A to PC B
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Address Resolution Protocol (ARP)
192.168.10.2
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
ARP Cache
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
ARP Issues
Broadcasting
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
ARP Issues (Cont.)
ARP�spoofing
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Data Link Layer Frame: WANs
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
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Network Fundamentals
Lecture 08: Physical Layer
IE1020|�Network�Fundamentals�|�Lecture�08|�Ms.�
Physical Layer
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Physical Layer Cont.
• The�physical�layer�encodes�the�frames�and�
creates� the� signals� (electrical� /� optical� /� radio)� that� represent� the�
bits�in�each�frame
• These�signals�are�then�sent�on�the�media,�one�at�a�time
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Physical Layer Cont.
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Physical Layer Cont.
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Physical Layer Cont.
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Physical Layer Cont.
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Physical Layer Cont.
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Physical Layer Cont.
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Physical Layer Cont.
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Physical Layer Cont.
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Physical Layer Cont.
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Physical Layer Cont.
Standards
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Physical Layer Cont.
Standards�cont.
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Signals
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Encoding and Modulation
• Two�techniques�used�to�map�information�or�data�into�different�formats�
and�send�through�the�transmission�media
• Encoding� is� the� process� of� preparing� information� (data)� for� efficient�
and�accurate�transmission�
data�->�signals
• Modulation� is� the� process� of� combining� information� (signals)� with� an�
electronic�or�optical�carrier,�so�that�it�can�be�transmitted�to�distance�
signals�+�carrier
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Encoding
• When�data�is�transmitted,�it�must�be�mapped�to�a�signal�pattern��
• The� signal� pattern� should� make� transmission� as� efficient� and� as� reliable� as�
possible
•
•
•
•
Computing
Digital�data�->�Digital�signal
Digital�data�->�Analog�signal
Analog�data�->�Analog�signal
Analog�data�->�Digital�signal
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Encoding Cont.
Line�
Coding
• Unipolar:�Uses�only�one�voltage�level
• Polar:�Uses�two�voltage�levels�(positive�and�negative)
• Bi-polar:�Uses�three�voltage�levels�(positive,�negative,�and�zero)
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Encoding Cont.
Unipolar
Non-Return�to�Zero�
(NRZ)�
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Encoding Cont.
Polar
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Encoding Cont.
Polar�
Cont.
• NRZ-L:�Level�of�the�signal�depends�on�the�state�of�the�bit�
(1�or�0)
• NRZ-I:�If�a�“1”�is�encountered,�then�the�signal�is�inverted
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Encoding Cont.
Polar�
Cont.
• RZ:�Signal�goes�to�0�in�the�middle�of�each�bit
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Encoding Cont.
Polar�
Cont.
Manchester
• �A�transition�for�every�bit�in�the�middle�of�the�bit�interval
• �(+)�to�(-)�represent�a�“0”,�(-)�to�(+)�represent�a�“1”�
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Encoding Cont.
Polar�
Cont.
Differential�Manchester
• Transition�for�every�bit�in�the�middle�of�the�bit�interval
• Transition�at�the�beginning�of�the�bit�cell�if�the�next�bit�is�
"0“
• NO� Transition� at� the� beginning� of� the� bit� cell� if� the� next�
bit�is�"1�"�
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Encoding Cont.
Bi-Polar
Alternate�Mark�Inversion�(AMI)
• Zero�voltage�represents�“0”�
• “1”s�are�represented�by�alternating�positive�and�negative�
voltages
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Modulation
• A� technique� in� which� information� signal� is� transmitted� to� the� receiver�
with�the�help�of�carrier�signal
ü We�combine�both�carrier�signal�and�information�signal�
ü The�carrier�wave�is�altered�in�a�way�that�it�is�able�to�carry�information�
on�it
• Analog� Modulation:� the� input� information� signal� is� in� the� analog�
format
• Digital�Modulation:�the�input�information�signal�is�in�the�digital�format
• However,�in�both�scenarios
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
• The�carrier�signal�is�an�analog�signal
Modulation Cont.
Input�Signal
(Information�
Signal)
Analog�/�Digital
MODULATION
Output�Signal
(Modulated�
Signal)
Analog
Carrier�Signal
Analog
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Modulation Cont.
Analog�Modulation
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Modulation Cont.
Analog�Modulation
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Modulation Cont.
Analog�Modulation
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Modulation Cont.
Digital�
Modulation
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Modulation Cont.
Analog�signal�to�Digital�signal�modulation:�
Pulse�Code�Modulation�(PCM)
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Modulation Cont.
Analog�signal�to�Digital�signal�modulation:�
Pulse�Code�Modulation�(PCM)
Encoding
• 8�bits/�16�bits/�32�bits�
etc.
Ex:
8�bits�=�28�
combinations
����������=�256�
����������=�0�to�255�
(levels)
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Data Transfer Rates
• Different� physical� media� support� the� transfer� of� bits� at�
different�rates
• Data�transfer�->�bandwidth�and�throughput
• Bandwidth�is�the�capacity�of�a�medium�to�carry�data
• A� combination� of� factors� determines� the� practical� bandwidth�
of�a�network:
ü The�properties�of�the�physical�media
ü The�technologies�chosen�for�signaling�and�detecting�network�signals
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Data Transfer Rates Cont.
• Throughput� is� the� measure� of� the� transfer� of� bits� across� the�
media�over�a�given�period�of�time
• Throughput� usually� does� not� match� the� specified� bandwidth� in�
physical�layer�implementations
• Many�factors�influence�throughput,�including:
ü The�amount�of�traffic
ü The�type�of�traffic
ü The�latency�created�by�intermediate�network�devices
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Bandwidth
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Throughput
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Multiplexing
• Whenever� the� bandwidth�of�a�medium�linking�two�devices� is�
greater�than�the�bandwidth�needs�of�the�devices,�the�link�can�
be�shared.�
• Multiplexing� is� the� set� of� techniques� that� allows� the�
(simultaneous)� transmission� of� multiple� signals� across� a�
single�data�link.
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Multiplexing Cont.
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Frequency Division Multiplexing (FDM)
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Wavelength Division Multiplexing (WDM)
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Time Division Multiplexing (TDM)
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Types of Physical Media
Wireless
Copper�Cables
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
Transmission Media Impairments
• Attenuation�–loss�of�energy
• Distortion�–change�in�the�shape�of�signal
• Noise�–random�or�unwanted�signal�that�mixes�up�with�the�original�signal�
IE1020|�Network�Fundamentals�|�Lecture�09|�Ms.�
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