TCP Concepts - PDF Presentation
Slide Presentation: TCP Concepts - Congestion Control, Header Format & Timer Management
TCP Concepts - PDF Presentation
Slide 1: Title Slide
Title: Transmission Control Protocol (TCP): Congestion Control, Header Format & Timer Management
Presented by: [Your Name]
Date: [Insert Date]
TCP Concepts - PDF Presentation
Slide 2: Introduction to TCP
- Transmission Control Protocol (TCP) is a connection-oriented protocol in the transport layer.
- Ensures reliable, ordered, and error-checked delivery of data between applications.
- Key features include:
- Reliable data transfer
- Flow control
- Congestion control
- Sequencing
- Full-duplex communication
TCP Concepts - PDF Presentation
Slide 3: TCP Congestion Control - Overview
- TCP must ensure that the sender does not overwhelm the network.
- Congestion control mechanisms are used to detect and respond to congestion in the network.
- TCP employs multiple algorithms:
- Slow Start
- Congestion Avoidance
- Fast Retransmit
- Fast Recovery
TCP Concepts - PDF Presentation
Slide 4: Slow Start
- Starts with a small congestion window (cwnd), typically 1 MSS (Maximum Segment Size).
- Increases exponentially for each ACK received.
- cwnd doubles each RTT until it reaches the slow start threshold (ssthresh).
- When cwnd >= ssthresh, it enters congestion avoidance.
Diagram: Exponential growth curve of cwnd over RTT (Slow Start Phase)
TCP Concepts - PDF Presentation
Slide 5: Congestion Avoidance
- After reaching the ssthresh, cwnd increases linearly (by 1 MSS per RTT).
- Helps in gradually probing for available bandwidth.
- Prevents abrupt congestion caused by exponential growth.
Diagram: Linear growth of cwnd during congestion avoidance phase
TCP Concepts - PDF Presentation
Slide 6: Fast Retransmit and Fast Recovery
Fast Retransmit:
- Triggered after receiving 3 duplicate ACKs (indicating packet loss).
- Retransmits the lost segment immediately.
Fast Recovery:
- Instead of dropping to 1 MSS (like in slow start), it sets cwnd to ssthresh and enters congestion avoidance.
- Avoids performance penalty of slow start.
Diagram: cwnd drop and recovery after packet loss
TCP Concepts - PDF Presentation
Slide 7: TCP Header Format
Minimum TCP Header Size: 20 bytes (without options)
Fields in TCP Header:
Field | Size (bits) | Description
--------------------|-------------|------------------------------------------
Source Port | 16 | Port number of the sender
Destination Port | 16 | Port number of the receiver
Sequence Number | 32 | Byte number of the first byte in segment
Acknowledgment No. | 32 | Next expected byte from the receiver
Data Offset |4 | Header length
Reserved |3 | Reserved for future use
Control Bits |9 | SYN, ACK, FIN, URG, etc.
Window Size | 16 | Flow control mechanism
Checksum | 16 | Error detection
Urgent Pointer | 16 | Urgent data position
Options | Variable | E.g., Maximum Segment Size
Diagram: TCP header structure diagram with labeled fields
TCP Concepts - PDF Presentation
Slide 8: TCP Timer Management
TCP uses several timers to manage reliable communication.
1. Retransmission Timer:
- Set when a segment is sent.
- If ACK not received in time, segment is resent.
- Based on Estimated RTT and Deviation.
2. Persistence Timer:
- Avoids deadlock when window size is 0.
- Periodically probes receiver for window update.
3. Keepalive Timer:
- Checks if the connection is still alive after inactivity.
- Sends keepalive probe if no data has been sent for a long time.
4. Time-Wait Timer:
- Used after connection termination.
- Prevents overlap of segments from old connections.
Diagram: Flowchart of timer triggers and responses
TCP Concepts - PDF Presentation
Slide 9: Conclusion
- TCP ensures robust and efficient transmission of data.
- Congestion control prevents overload and manages bandwidth effectively.
- TCP header provides all necessary control information.
- Timer management maintains reliability and proper connection lifecycle.
TCP Concepts - PDF Presentation
Slide 10: Questions for Review
1. What is the difference between flow control and congestion control?
2. Explain the purpose of the slow start algorithm in TCP.
3. What triggers fast retransmit in TCP?
4. Name the fields in a TCP header and their purposes.
5. How does the retransmission timer differ from the persistence timer?
6. What is the purpose of the time-wait timer in TCP?
TCP Concepts - PDF Presentation
Slide 11: Thank You
Any Questions?
