The document discusses the transport layer of the OSI model. It describes how the transport layer is responsible for end-to-end communication over a network by managing error correction and reliability. The two main protocols of the transport layer are UDP and TCP. UDP provides unreliable data transmission while TCP establishes connections and provides reliable in-order delivery through mechanisms like acknowledgments and flow control.

2. GROUP
MEMBERS
USMAN
IMRAN/16237
ALI
ABBASI/16009
FAISAL
MEHMOOD
KHAN/16051

4. • OSI stand for Open systems interconnection.
• The Open Systems Interconnection (OSI) model (ISO/IEC 7498-
1) is a product of International Organization for
Standardization(ISO).
• The OSI model is a way of describing how different applications
and protocols interact on network-aware devices.

5. • The OSI model divides the complex task of computer-to-computer
communications, traditionally called internetworking, into a series
of stages known as layers.
• The OSI model contains seven layers in two groups:
Lower layers -
1. Physical
2. Data link
3. Network
4. Transport
Upper layers -
5. Session
6. Presentation
7. Application

6. seven-layer model

7. Data format of “OSI” Layers

8. • By separating the network communications into logical smaller
pieces.
• It simplifies how network protocols are designed.
• It was designed to ensure different types of equipment (such
as: network , adapters , hub , and routers) would all be
compatible even if built by different manufacturers.
• The OSI model also make the network design more extensible
as new protocols and other network services are generally
easier to add a layered architecture than to a monolithic one.

9. • The transport layer is the 4th layer in the open system
interconnection (OSI) model.
• It is responsible for end-to-end communication over a
network.
• The transport layer is also responsible for the management of
error correction, providing quality and reliability to the end
user.
• This layer enables the host to send and receive error corrected
data, packets or messages over a network and is the network
component that allows multiplexing.

10. • It collects data from upper layer.
• It converts them into segments and then gave it to lower layer.
• Transport layer allot sequence number to the segments and
send these segments to the session layer
• It takes packets from network layer and convert them into
segments and the process go on.

11. CONNECTION ORIENTED
• This method is often called a "reliable" network service.
• It can guarantee that data will arrive in the same order

12. Byte-oriented processing
• It process data in the form of bytes instead of existing message format.
• It became easy to process data into bytes.
Congestion control
• This mechanism controls traffic entry into a network.
• It avoid the overflow in network.
In order delivery
• It guarantees that packets of data are received in the same order as they
were sent .
• It is done through the use of segment numbering.

13. • Reliable delivery
• Due to the network over flow and errors, the packets may be lost during
the transmission.
• With the help of an error detection code, such as a checksum, it checks
that whether the data is corrupted or not.
• it also verifies the correct receipt by sending an ACK message to the
sender.
Flow control
• It manages the rate of data transmission between two nodes.
MULTIPEXING
• It take data from a multiple nodes and send them through a single link.

14. Protocols of transport layer
• The main protocols of Transport layer.
• UDP (User Datagram Protocol)
• TCP (Transmission Control PROTOCOLS)

15. • UDP is a simple, transport layer protocol that does not
guarantee any reliability .
• A UDP packet is called as datagram and is divided into two
parts: a “header” and “ payload”
• It supports both multicasting and broadcasting.
• UDP is considered where the in time delivery of data is
important rather than reliable delivery.

16. • UDP employs a cyclic redundancy check (CRC) .
• It can detect any error in the packet.
• If it detects an error in the packet, it is then declared lost and discarded
rather than resending the packet.
• UDP does not provide any congestion control mechanism.
• Basic operation of UDP
• UDP encapsulates the data of users into datagram.
• Finally forwards these Datagram to the IP layer for the transmission

17. TRANSMISSION CONTROL
PROTOCOL(TCP)
• Transmission control protocol
• Connection-oriented .
• Positive acknowledgments.
• It sends 17 messages for connection establishment.
– 6 to find the IP (Internet Protocol) address
– 3 for connection establishment of TCP
– 4 for HTTP request and acknowledgement
• Request: I got your request and I will send the data
• Reply: Here is the data you requested; I got the data
– 4 messages for tearing down TCP connection.

18. Sliding window Control or 3-Way
Handshake
 Sender
• Buffer or Sliding Window
 Receiver
• Acknowledgement or ACK
packets.
This Mechanism is called
Window Based Transmission

20. Functions of TCP
•Data Transfer
•Reliable Delivery
•Flow Control
•Multiplexing

24. Thank You !!!