Podcast
Questions and Answers
What is the primary responsibility of the transport layer in a network?
What is the primary responsibility of the transport layer in a network?
- End-to-end communication over a network (correct)
- Routing packets between networks
- Ensuring data security
- Physical transmission of data packets
Which layer of the OSI model is the transport layer?
Which layer of the OSI model is the transport layer?
- Fifth layer
- First layer
- Fourth layer (correct)
- Second layer
Why does connection-oriented communication, like TCP, add more network load compared to UDP?
Why does connection-oriented communication, like TCP, add more network load compared to UDP?
- It delivers messages in random order
- It uses a less secure protocol
- It requires acknowledgment for each message delivered (correct)
- It transmits data without any handshakes
What is the purpose of assigning numbers to packets for same-order delivery?
What is the purpose of assigning numbers to packets for same-order delivery?
Which protocol is commonly used for connection-oriented communication at the transport layer?
Which protocol is commonly used for connection-oriented communication at the transport layer?
Where do transport layer protocols run within a network?
Where do transport layer protocols run within a network?
Which layer ensures that the data transmitted is the same as the data received and it isn't corrupt?
Which layer ensures that the data transmitted is the same as the data received and it isn't corrupt?
What aspect of data transmission does flow control manage?
What aspect of data transmission does flow control manage?
What does Congestion control prevent?
What does Congestion control prevent?
Which protocol is connectionless and offers fast delivery but lacks congestion and flow control?
Which protocol is connectionless and offers fast delivery but lacks congestion and flow control?
What characteristic distinguishes TCP from UDP concerning delivery?
What characteristic distinguishes TCP from UDP concerning delivery?
In Slow Start algorithm, how does the congestion window increase?
In Slow Start algorithm, how does the congestion window increase?
Which protocol establishes sequencing and acknowledgment for data delivery?
Which protocol establishes sequencing and acknowledgment for data delivery?
What indicates a congestion situation in the Congestion Avoidance algorithm?
What indicates a congestion situation in the Congestion Avoidance algorithm?
What happens when congestion is indicated by duplicate ACKs in TCP?
What happens when congestion is indicated by duplicate ACKs in TCP?
In terms of speed, which protocol is noted to be faster compared to the other?
In terms of speed, which protocol is noted to be faster compared to the other?
In which scenario does Congestion Avoidance algorithm slow the transmission rate?
In which scenario does Congestion Avoidance algorithm slow the transmission rate?
What initiates the Fast Retransmit algorithm in TCP?
What initiates the Fast Retransmit algorithm in TCP?
What is the purpose of the TCP protocol?
What is the purpose of the TCP protocol?
How does TCP ensure error-free data delivery?
How does TCP ensure error-free data delivery?
What is the purpose of the Acknowledgement number in TCP?
What is the purpose of the Acknowledgement number in TCP?
How does TCP handle out-of-order segments during transmission?
How does TCP handle out-of-order segments during transmission?
What does the Data offset in TCP represent?
What does the Data offset in TCP represent?
Why does TCP use sequence numbers?
Why does TCP use sequence numbers?
What does receiving three or more duplicate ACKs indicate to the sender?
What does receiving three or more duplicate ACKs indicate to the sender?
What is the name of the algorithm where the sender does not wait for a retransmission timer to expire after receiving three or more duplicate ACKs?
What is the name of the algorithm where the sender does not wait for a retransmission timer to expire after receiving three or more duplicate ACKs?
In Fast Recovery, how does the sender resume transmission after detecting congestion?
In Fast Recovery, how does the sender resume transmission after detecting congestion?
Why is flow control necessary in data communication between two machines?
Why is flow control necessary in data communication between two machines?
What feedback mechanism does the receiver use to inform the sender it is overwhelmed with data?
What feedback mechanism does the receiver use to inform the sender it is overwhelmed with data?
What is the purpose of the time out in data communication?
What is the purpose of the time out in data communication?
Study Notes
Transport Layer Services and Protocols
- The transport layer is the fourth layer in the OSI model and the second layer in the TCP/IP model.
- It is responsible for end-to-end communication over a network and provides logical communication between application processes running on different hosts.
- The transport layer collects segments from the Application Layer and transmits them into the Network Layer, and reassembles segments into fully formed messages and passes them on to the Application Layer.
Services Provided by the Transport Layer
- Connection-Oriented Communication: establishes a handshake protocol to ensure a connection is robust before data is exchanged.
- Same Order Delivery: ensures packets are delivered in strict sequence by assigning them a number.
- Data Integrity: ensures data integrity across all layers using checksums.
- Flow Control: ensures data is sent at a rate acceptable for both communicating devices.
- Multiplexing: allows simultaneous applications over a network.
- Traffic Control: identifies indications of overloaded nodes and reduces flow rates to remediate issues.
Transport Layer Protocols
- Transmission Control Protocol (TCP):
- Connection-oriented
- Reliable, in-order delivery
- Congestion control
- Flow control
- User Datagram Protocol (UDP):
- Connectionless
- Unreliable, unordered delivery
- Fast, but no congestion control or flow control
Comparison between UDP and TCP Protocols
- UDP: connectionless, unreliable, fast, no sequencing, no acknowledgment
- TCP: connection-oriented, reliable, slow, segment sequencing, acknowledgment, congestion control, and flow control
TCP Congestion Control Algorithms
- First: Slow Start - initializes a congestion window to one segment, which increases by one segment for each ACK returned.
- Second: Congestion Avoidance - slows the transmission rate when congestion occurs.
- Third: Fast Retransmit - retransmits a segment when three or more duplicate ACKs are received.
- Fourth: Fast Recovery - resumes transmission with a larger window, incrementing as if in Congestion Avoidance mode.
Flow Control
- Ensures that a transmitting station does not overwhelm a receiving station with data.
- The receiver sends feedback to the sender to inform them when they are overwhelmed with data.
- Time out: the time to wait before the sender will retransmit the packet.
Flow Control Methods
- Stop-and-Wait
- Transmission Control Protocol (TCP) Connection Oriented: implements mechanisms to setup and tear down a full duplex connection, guarantee error-free and ordered delivery, and control traffic.
TCP Segments
- Application data broken into segments for transmission.
- Segmentation is done by TCP, according to its best strategy.
- Each segment is placed into an IP packet.
- TCP uses port numbers to connect programs.
- The sequence number of the first data byte in the segment is sent to the destination host.
- The receiving TCP uses sequence numbers to rearrange segments and eliminate duplicate segments.
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Description
Learn about how TCP utilizes Slow Start algorithm for congestion control and the role of flow control in preventing receivers from being overwhelmed. Understand how the congestion window size is dynamically adjusted based on ACKs returned by the receiver.
