Transport Layer = Transport Layer [OSI Model]
Transport Layer has same function as Transport Layer of OSI Model, it is also known as Host To Host Layer:
Transport Layer
- The Transport layer is responsible to reassembles segments into a data stream.
- Transport layer provide end to end data transport services.
- It can establish a logical connection between the sending host and destination host on an inter-network.
- It is also responsible to hide sensitive details of data from networks and to providing data transmission in a transparent mode.
- Transport layer can be connection-less or connection oriented. Because TCP and UDP both work at the Transport layer. Where TCP is a connection oriented means provide reliable communication and UDP is connection-less means provide unreliable communication.
- Because Transport layer can be connection oriented, so it also will be use acknowledgments, sequencing, windowing, error control and flow control.
Transport Layer
- The Transport layer is responsible to reassembles segments into a data stream.
- Transport layer provide end to end data transport services.
- It can establish a logical connection between the sending host and destination host on an inter-network.
- It is also responsible to hide sensitive details of data from networks and to providing data transmission in a transparent mode.
- Transport layer can be connection-less or connection oriented. Because TCP and UDP both work at the Transport layer. Where TCP is a connection oriented means provide reliable communication and UDP is connection-less means provide unreliable communication.
- Because Transport layer can be connection oriented, so it also will be use acknowledgments, sequencing, windowing, error control and flow control.
Below protocols come under the Transport Layer :-
Transmission Control Protocol (TCP)
- TCP is reliable protocol and provide connection oriented reliable communication. TCP provide guaranteed delivery of data to the receiver
- If data will be lost in transit, TCP will recover the data and resend it
- TCP also check the errors of packet and track packets so data will not be lost or corrupt.
- It uses some mechanism for reliability and recovery like Acknowledgement, Sequencing, Windowing and Flow control.
- TCP is slower than UDP and creates a lot of overhead, because it has a lot mechanism like Acknowledgement, Sequencing, Windowing and Flow control.
- TCP will be used for below applications, which required high reliability and timing has less priority.
-World Wide Web (HTTP, HTTPS)
-Secure Shell (SSH)
-File Transfer Protocol (FTP)
-Email (SMTP, IMAP/POP)
Flow Control
Figure : Transmitting The Segment With Flow Control
- Flow control prevents overflowing of buffers in the receiving host - when a sending host is sending the segment to receiving host continuously and buffer on the receiver side has filled then in this situation receiving host will notify the sending host about this event after that receiving host will stop transmission and wait for permission to start transmission again. Overflowing of buffer can result in lost data.
Acknowledgement -
- It guarantees that the data will not be duplicated or lost. It will be accomplished with positive acknowledgment with re-transmission
- Receiver communicates with the sender by sending an acknowledgment, actually receiver will send acknowledgement back to the sender when it will receive data.
Windowing -
Figure : Windowing
Windows are used to control the amount of outstanding, unacknowledged data segments. In windowing user can increase or decrease the size of window anytime.
Flow Control
Windows are used to control the amount of outstanding, unacknowledged data segments. In windowing user can increase or decrease the size of window anytime.
Figure : Transmitting The Segment With Flow Control
- Flow control prevents overflowing of buffers in the receiving host - when a sending host is sending the segment to receiving host continuously and buffer on the receiver side has filled then in this situation receiving host will notify the sending host about this event after that receiving host will stop transmission and wait for permission to start transmission again. Overflowing of buffer can result in lost data.
- It guarantees that the data will not be duplicated or lost. It will be accomplished with positive acknowledgment with re-transmission
- Receiver communicates with the sender by sending an acknowledgment, actually receiver will send acknowledgement back to the sender when it will receive data.
Figure : Windowing
User Data-gram Protocol (UDP)
- UDP is unreliable protocol and provide connection-less unreliable communication, it does not provide guaranteed delivery of data and there is no any mechanism to check the packet error and tracking.
- There are no any mechanism like Acknowledgement, Sequencing, Windowing and Flow control.
- UDP does not sequence the segment and does not care in which order the segments arrive at the destination.
- There are low overhead.
- UDP will be used for below applications, which required high speed and efficiency.
-VPN tunneling
-Streaming videos
-Online games
-Live broadcasts
-Domain Name System (DNS)
-Voice over Internet Protocol (VoIP)
-Trivial File Transfer Protocol (TFTP)
- UDP is unreliable protocol and provide connection-less unreliable communication, it does not provide guaranteed delivery of data and there is no any mechanism to check the packet error and tracking.
- There are no any mechanism like Acknowledgement, Sequencing, Windowing and Flow control.
- UDP does not sequence the segment and does not care in which order the segments arrive at the destination.
- There are low overhead.
- UDP will be used for below applications, which required high speed and efficiency.
Hello and welcome to networktopic Blog. My name is Anubhav. I am a Senior Network Egineer. I have created this blog specially to serve interview questions and answer on Network Routing and Switching, I will try my best to serve correct and updated networking knowledge for you as per my corporate experience.
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