GROUPMEMBERS

USMAN IMRAN/162

37

ALI ABBASI/160

09

FAISAL MEHMOOD

KHAN/16051

FINAL PROJECTOF

INTRODUCTION TO TELECOMMUNICATION

TRANSPORT LAYER OF OSI MODEL

WHAT IS OSI MODEL?

• 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.

LAYERS OF OSI MODEL

• 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

seven-layer model

Data format of “OSI” Layers

Benefits of the OSI Model

• 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.

WHAT IS TRANSPORT LAYER?

• 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.

WORKING OF TRANSPORT LAYER

• 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.

SERVICES BY TRANSPORT LAYER

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

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.

• 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.

Protocols of transport layer

• The main protocols of Transport layer.

• UDP (User Datagram Protocol)

• TCP (Transmission Control PROTOCOLS)

USER DATAGRAM PROTOCOL (UDP)

• 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.

• 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

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.

Sliding window Control or 3-Way Handshake

Sender• Buffer or Sliding Window Receiver• Acknowledgement or ACK packets. This Mechanism is calledWindow Based Transmission

Functions of TCP

•Data Transfer

•Reliable Delivery

•Flow Control

•Multiplexing

DIFFERENCES

Thank You !!!