🌐 Introduction to TCP

Transmission Control Protocol (TCP) is a connection-oriented protocol that provides reliable, ordered, and error-free delivery of data between applications. It ensures data integrity, error recovery, and flow control during data transmission.

πŸ”„ TCP Service Model

TCP provides the following services:

  1. Reliable Data Transfer: Guarantees the delivery of data in the correct order.
  2. Flow Control: Prevents network congestion by adjusting the rate of data transmission.
  3. Error Detection and Recovery: Uses checksums to detect errors and requires retransmissions in case of loss.
  4. Connection Establishment: Three-way handshake to establish a reliable connection.
  5. Connection Release: A formal process to terminate a connection.

🏷 TCP Segment Header

The TCP segment header includes:

  • Source Port: Port number at the sender’s end.
  • Destination Port: Port number at the receiver’s end.
  • Sequence Number: Number assigned to the first byte of data in this segment.
  • Acknowledgment Number: Expected sequence number for the next byte from the receiver.
  • Flags: Control bits like SYN, ACK, FIN to manage the connection state.
  • Window Size: Specifies the amount of data the receiver can buffer.
  • Checksum: Ensures data integrity.

πŸ”€ TCP Connection Establishment

  1. SYN: The client sends a SYN packet to the server to initiate a connection.
  2. SYN-ACK: The server responds with a SYN-ACK packet, acknowledging the client’s SYN request.
  3. ACK: The client sends an ACK packet back to the server, confirming the connection.

This three-way handshake ensures a reliable connection is established before data transfer begins.

πŸͺ’ TCP Connection Release

  1. FIN: The sender sends a FIN packet to indicate that no more data will be transmitted.
  2. ACK: The receiver acknowledges the FIN packet.
  3. FIN-ACK: The receiver sends a FIN packet to the sender to close the connection.
  4. Final ACK: The sender acknowledges the FIN packet, and the connection is closed.

πŸ„β€β™‚οΈ TCP Sliding Window

  • Sliding Window Protocol: A method for controlling the flow of data between sender and receiver. It helps in managing how much data can be sent without receiving an acknowledgment.

  • The sender window determines how many bytes can be sent before receiving an acknowledgment.

  • The receiver window specifies the amount of available buffer space.

πŸŒͺ TCP Congestion Control

  • TCP uses congestion control to prevent network overload. Techniques include:
    1. Slow Start: Starts by sending small amounts of data and increases gradually.
    2. Congestion Avoidance: Uses additive increase/multiplicative decrease (AIMD) to manage data flow.
    3. Fast Retransmit: Quickly retransmits packets suspected of being lost.
    4. Fast Recovery: Quickly recovers after packet loss by reducing the transmission rate.

🧠 Insights

  • TCP ensures that applications can reliably communicate over the inherently unreliable Internet.
  • The three-way handshake guarantees synchronization between the sender and receiver before data exchange begins.
  • Sliding window and congestion control ensure that the connection adapts to network conditions, improving efficiency and avoiding congestion.

πŸ”— Links