Transport Layer: Connection-Oriented Protocols

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Questions and Answers

What is the primary purpose of sequence numbers in TCP?

To allow for the reassembly of data in the correct order, even if segments arrive out of order.

What is the main difference between connection-oriented and connectionless protocols?

Connection-oriented protocols, like TCP, establish a connection before sending data, while connectionless protocols, like UDP, do not establish a connection before sending data.

Why is UDP suitable for streaming video?

Because it does not guarantee delivery, and losing a few frames of video will not significantly impact the viewing experience.

What is the main advantage of using UDP over TCP for data transfer?

UDP has less overhead than TCP, which means more bandwidth is available for actual data transfer. Signup and view all the answers

What happens to TCP segments that are resent due to errors at lower layers?

They can still be reassembled in the correct order using sequence numbers, even if they arrive out of order. Signup and view all the answers

Why is it important to establish a connection before sending data in TCP?

To ensure guaranteed delivery of data and to establish a reliable connection. Signup and view all the answers

What is the purpose of acknowledgments in TCP?

To confirm that data has been received correctly and to ensure reliable delivery. Signup and view all the answers

What is the trade-off between using TCP and UDP for data transfer?

TCP provides guaranteed delivery but has more overhead, while UDP has less overhead but does not guarantee delivery. Signup and view all the answers

What is the primary purpose of a connection-oriented protocol?

To ensure that all data has been properly transmitted by establishing a connection and using acknowledgments. Signup and view all the answers

What happens if a single bit of data doesn't get transmitted properly?

The resulting data is often incomprehensible by the receiving end. Signup and view all the answers

What are some reasons why traffic might not reach its destination?

Line errors, congestion, or physical damage to infrastructure such as a construction company cutting a fiber cable. Signup and view all the answers

What is the purpose of checksums in IP and Ethernet protocols?

To ensure that all the data received was correct. Signup and view all the answers

Why is TCP in the best position to know what data successfully got delivered?

Because TCP expects an ACK for every bit of data it sends. Signup and view all the answers

What happens to data that doesn't pass the checksum test at the IP or Ethernet level?

It is discarded. Signup and view all the answers

What is the role of the transport layer protocol in resending data?

To determine when to resend data that didn't pass the checksum test or was lost in transmission. Signup and view all the answers

Why is it important for connection-oriented protocols to form connections and use acknowledgments?

To protect against data loss or corruption due to the unreliability of the internet. Signup and view all the answers

Study Notes

Connection-Oriented Protocols

Connection-oriented protocols establish a connection to ensure proper data transmission.
Every data segment sent is acknowledged, enabling both ends to track delivered and missing bits.
Vital for reliable communication over the busy internet, preventing incomplete or corrupted data delivery.

Importance of Acknowledgments

TCP expects an acknowledgment (ACK) for each data segment sent, making it aware of successful delivery.
If a data segment fails checksum verification at lower levels (IP, Ethernet), it gets discarded; TCP is responsible for resending lost data.

Sequence Numbers

TCP uses sequence numbers to track the order of data segments.
Segments may arrive out of order, but sequence numbers allow for reassembly in the correct order upon receipt.

Overhead of TCP

Connection establishment, continuous acknowledgments, and connection teardown contribute to significant overhead.
This overhead is justified for critical data where delivery assurance is paramount.

Connectionless Protocols

UDP (User Datagram Protocol) is a common connectionless protocol that operates without establishing connections or sending acknowledgments.
Best for less critical data, such as streaming video, where some data loss doesn't substantially impact quality.

Benefits of UDP

By eliminating TCP's overhead, UDP allows for more bandwidth to be used for actual data transfer.
Ideal for scenarios where speed is prioritized over reliability, like real-time video streaming.

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Description

This quiz covers the basics of connection-oriented protocols, specifically TCP, and how they ensure reliable data transmission at the transport layer.