The document discusses transport layer protocols. It provides an overview of process-to-process delivery and addressing at the transport layer. Key points covered include connection-oriented vs connectionless services, reliable vs unreliable protocols, User Datagram Protocol (UDP), and Transmission Control Protocol (TCP). UDP is described as a connectionless and unreliable protocol, while TCP provides connection-oriented and reliable data transfer with features like flow control, error control, and numbering systems.

1. Asslam-o-Alaikum!
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2. Group Members
Name Roll No:
Jawad Altaf 19011519-004
Bilal Ahmed 19011519-007
Faizan Ahmed 19011519-009
Saddam Khalid 19011519-029
Nouman Ahmed 19011519-140

3. Objectives
 Process-to-Process Communication:
 Transport Layer.
 Addressing at Transport Layer.
 Connection Oriented Vs Connectionless
Service.
 Reliable Vs Unreliable.
 User Datagram Protocol(UDP)
 Transmission Control Protocol(TCP)

4. Transport Layer
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5.  Process-to-process delivery of message.
 Process is an application program running on a
host.
 Ensure that the whole message arrives intact
and in order.
 Service Point Address.
 Error control and flow control.
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Transport Layer

6.  Types of delivery:-
 Node-to-Node delivery
 Host-to-Host delivery
 Process-to-Process delivery
 Way to achieve process-to-process
communication
 Client/Server Paradigm
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Process-to-Process Delivery

7.  Types of delivery:
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Process-to-Process Delivery

8.  We need to deliver something to one specific
destination among many, we need an address.
 MAC address require at data link layer.
 IP address require at network layer.
 Port number require at transport layer.
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Addressing

9.  In the Internet model, the port numbers are 16-
bit integers between 0 and 65,535.
 Ephemeral(Temporary) port number:
 Client Process Port can be chosen randomly.
 Server Process Port cannot be chosen randomly.
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Addressing

10.  If Server Process Port chosen randomly then
problem can occur.
 Solution to the above problem of chosen.
 The internet has decided to use universal port
number also known as well-known(Permanent)
port.
 Every client process knows the well-known port
number of the corresponding server process.
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Addressing

11.  IANA Ranges:
 IANA (Internet Assigned Number Authority) has
divided the port numbers into three ranges:
 Well-known Ports: Ports ranging from 0 to 1023.
 Registered Ports: Ports ranging from 1024 to
49,151.
 Dynamic Ports: Ports ranging from 49,152 to
65,535.
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Addressing

12.  Socket Addressing:
 Process-to-Process delivery need two
identifiers: IP address and Port number.
 The combination of an IP address and a port
number is called a socket address.
 Server/Client socket address.
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Addressing

13.  Multiplexing:
 Several processes that need to send packets but one
transport layer protocol.
 Many-to-one relationship .
 Assign ports and add header to packets.
 De-multiplexing:
 One-to-many relationship.
 Receive datagrams from network layer.
 Error check and drop header then deliver.
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Multiplexing and Demultiplexing

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Multiplexing and Demultiplexing

15. Connection Oriented Vs
Connectionless Service
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16. Connection Oriented
In connection
oriented
Connection is
established.
Information is
sent.
Connection is
released.
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17. Connectionless Service
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In connection
less
Connection is
not established.
Information is
sent.
No matters
destination is
there

18. Connection Oriented Vs
Connectionless Service
Connection-oriented
Service
Connection-less Service
Connection
Prior connection needs
to be established.
No Prior connection needs to
be established.
Use:
Connection-oriented
service is preferred by
long and steady
communication.
Connection-less Service is
preferred by bursty
communication.
Retransmissi
on
Possible Not possible
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19. Connection Oriented Vs
Connectionless Service
feasibility
Connection-oriented
Service is feasible.
Connection-less Service is not
feasible.
Congestion
In connection-oriented
Service, Congestion is
not possible.
In connection-less Service,
Congestion is possible.
Reliability
Connection-oriented
Service gives the
guarantee of
reliability.
Connection-less Service does
not give the guarantee of
reliability.
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20. Connection Oriented Vs
Connectionless Service
Route In connection-oriented
Service, Packets follow
the same route.
In connection-less Service,
Packets do not follow the
same route.
Resource
Allocation
Connection-oriented
Services requires
Resource allocation..
Connection-less Service
requires resource
allocation.
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21. Reliable Vs Unreliable
Reliable Unreliable
A reliable service is one that
notifies the user if delivery fails.
An unreliable one does not
notify the user if delivery fails.
End stations running reliable
protocols will work together to
verify the transmission of data to
ensure accuracy and integrity of
the data.
Unreliable protocols makes no
effort to set up a connection. It
cannot ensure accuracy and
integrity of the data.
A reliable system will set up a
connection and verify that: all
data transmitted is controlled in
an orderly fashion,
Unreliable protocols don't
check to see if the data was
received or not.
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22. Reliable Vs Unreliable
It make provisions for recovering
from errors or lost data.
It usually don't make any
provisions for recovering from
errors or lost data.
Reliable delivery can be
contrasted with best-effort
delivery, where there is no
guarantee that messages will be
delivered quickly, in order, or at
all.
Data flow rate is comparatively
fast as it does not ensures
integrity.
Transmission Control Protocol
(TCP) is a typical reliable
protocol.
User Datagram Protocol (UDP)
is an example of an unreliable
protocol.
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23. User Datagram Protocol (UDP)
 User Datagram Protocol (UDP) is a Transport
Layer protocol UDP is a part of Internet
Protocol suite, referred as UDP/IP suite.
 Unlike TCP, it is unreliable and connectionless
protocol. So, there is no need to establish
connection prior to data transfer.
 User Datagram Protocol (UDP) is more
efficient in terms of both latency and
bandwidth.
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24. UDP Operations
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25.  Connectionless service.
 Flow and error control.
 Encapsulation and decapsulation
 Queuing
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UDP Operations

26.  User Datagram Protocol (UDP) is
a connectionless protocol.
 UDP sends independent datagram.
 there is no connection establishment and no
connection termination.
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Connectionless service

27.  UDP is a very simple
 It is unreliable transport protocol.
 There is no flow control and hence no window
mechanism.
 There is no error control mechanism in UDP
except for the checksum.
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Flow and Error control

28.  To send a message from one process to another,
the UDP protocol encapsulates and
decapsulates messages in an IP datagram.
 In Encapsulation, the data moves from upper
layer to the lower layer
 Each layer includes a bundle of information
known as a header along with the actual data.
 It occur on the source computer.
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Encapsulation and decapsulation

29. Encapsulation and decapsulation
 In decapsulation, the data moves from the
lower layer to the upper layers.
 Each layer unpacks the corresponding headers
to obtain the actual data.
 It occurs on the destination computer.
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30. Encapsulation and decapsulation
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31.  In UDP queuing is associated with ports.
 UDP process creates incoming and outgoing
queues.
 Queue functions as long as the process is
running.
 When process is terminates, the queue are
destroyed.
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Queuing

32. 30
Queuing

33.  Suitable for a process with internal flow and
error control mechanisms such as TFTP
 Suitable for a process that requires simple
request-response communication with little
concern for flow and error control, not suitable
for FrP which sends a bulk of data.
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Uses of UDP

34.  Suitable for multicasting. Multicasting is
available in UDP but not in TCP.
 Used for management processes such as
SNMP
 Used for some route updating protocols such
as RIP
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Uses of UDP

35. Transmission Control
Protocol
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36. TCP
 Process to Process (Program to Program)
protocol.
 Connection Oriented Protocol.
 Virtual connection between two TCPs to send
data.
 Also called connection-oriented, reliable
transport protocol.
 Adds connection-oriented and reliability
features to IP service
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37. TCP Services
 Process to Process Communication
 Stream Delivery Service
 Full Duplex Communication
 Connection Oriented Service
 Reliable Service
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38. TCP Segments
 Format

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39. TCP Segments
 Source Port Address
 Destination Port Address
 Sequence Number
 Acknowledgement Number
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40. TCP Connection
 Connection Establishment
 Three way Handshaking
 Data Transfer
 Connection Termination
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41. Flow Control
 Uses sliding Window
 Shrinking Window
 Moving right wall to left
 TCP Sliding Window
 Size is lesser of rwnd and cwnd
 No need to send full window’s worth of data
 Window open or closed but not shrunk
 Destination can send acknowledgment at
anytime unless result in shrinking window
 Receiver may shut down window
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42. Error Control
 Checksum
 Acknowledgment
 Retransmission
 Out-of-Order Segments
 Some scenarios
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43. TCP Features
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44. Numbering System
 Byte Number
 Sequence Number
 Acknowledgement Number
 Reliable transfer of data
Flow Control
Error Control
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TCP Features

45.  Numbering System: TCP keeps track of the
segments being transmitted or received by assigning
numbers.
 Byte Number: Byte Number assigned to data
bytes to be transferred.
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TCP Features

46.  Sequence Number: Sequence number of data
bytes of a segment in a session.
 Acknowledgement Number: When ACK flag is
set, this number contains the next sequence number
of the data byte expected and works as
acknowledgement of the previous data received.
TCP Features
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47.  Reliable transfer of data :
 Ordered data transfer - the destination host
rearranges according to sequence number
 Retransmission of lost packets - any cumulative
stream not acknowledged will be retransmitted
 Discarding duplicate packets
 Error-free data transfer
TCP Features
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48. 46
 Flow control:
 Receiver of the data controls the amount of data that
are to be sent by the sender.
 Numbering system allows TCP to use byte-oriented
flow control.
TCP Features

49.  Error Control: Error control in TCP is mainly
done through use of three simple techniques :
 Checksum – Every segment contains a checksum
field which is used to find corrupted segment.
 Acknowledgement – TCP has another
mechanism called acknowledgement to affirm that
the data segments have been delivered.
TCP Features
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50. Cont.…
 Retransmission – When a segment is missing,
delayed to deliver to receiver, corrupted when it is
checked by receiver then that segment is
retransmitted again.
TCP Features
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