Transport Layer Flashcards
What is the main function of the transport layer
Provides end-to-end communication between applications on different hosts.
What are the two main transport layer protocols
- TCP (Transmission Control Protocol)
- UDP (User Datagram Protocol).
What are the characteristics of TCP
- Connection-oriented (requires a handshake).
- Reliable – ensures ordered, complete data delivery.
- Error-checking with acknowledgments (ACKs).
- Slower due to overhead.
- Examples: HTTP, FTP, SMTP, Telnet.
What are the characteristics of TCP
- Connectionless (no handshake).
- Unreliable – best-effort delivery, no acknowledgments.
- Low overhead, faster than TCP.
- Examples: Video streaming, VoIP, Online gaming, DHCP.
What are the 4 hour functions of the transport layer
- Segmentation & Multiplexing – Breaks large data into smaller segments.
- Encapsulation & Identifying Applications - Adds transport layer headers.
- Reassembly – Puts data back together at the destination.
- Error Detection – Checks for corrupted data.
What are the additional features of TCP
- Connection establishment (3-way handshake).
- Flow control (dynamic window sizes).
- Error correction & retransmission.
- Connection termination (4-way handshake).
How does TCP establish a connection
Using a 3-way handshake:
- SYN – Client sends a synchronization request.
- SYN-ACK – Server acknowledges & sends SYN.
- ACK – Client acknowledges, connection established.
How does TCP terminate a connection
Using a 4-way handshake:
- FIN – Initiating host sends termination request.
- ACK – Other host acknowledges FIN.
- FIN – Other host sends its termination request.
- ACK – First host acknowledges, connection closed.
What is the function of port numbers
They uniquely identify specific applications running on a host.
What are the three types of ports?
Well-Known Ports (0-1023) – Standard services (e.g., HTTP=80, HTTPS=443).
Registered Ports (1024-49151) – Assigned to applications (e.g., MySQL=3306).
Dynamic Ports (49152-65535) – Used temporarily for client-side connections.
How does TCP ensure ordered delivery
- Uses sequence numbers to track packets.
- If packets arrive out of order, TCP reassembles them.
How does TCP handle delivery
- Sends packets independently.
- No reordering or retransmission if packets are lost.
- Faster but less reliable.
What happens if an acknowledgement (ACK is lost)
- TCP retransmits the missing data after a timeout.
- Ensures reliable data delivery.
What is window size in TCP
The amount of data a sender can transmit before needing an acknowledgment.
What is flow control
TCP adjusts the rate of data transmission to prevent overwhelming the receiver.
