TCP three-way handshake

Definition

The TCP three-way handshake is a method used to establish a reliable connection between a client and server in a network before data transmission occurs. This process ensures that both parties are ready to communicate and helps in synchronizing the sequence numbers for data packets. By confirming that both sides are synchronized and aware of each other, the handshake prevents data loss and establishes a robust session management framework.

5 Must Know Facts For Your Next Test

1. The TCP three-way handshake consists of three steps: the client sends a SYN packet to the server, the server responds with a SYN-ACK packet, and finally, the client sends an ACK packet back to the server.
2. This handshake process establishes both connection reliability and ensures that sequence numbers are properly synchronized between the client and server.
3. If any step of the three-way handshake fails, the connection is not established, preventing potential issues such as data loss or corruption.
4. The three-way handshake is crucial for applications requiring reliable communication, as it ensures that both parties are ready before data transfer begins.
5. After the handshake, both the client and server maintain a session state that allows for orderly data transfer until the session is terminated.

Review Questions

• What are the steps involved in the TCP three-way handshake, and why are they important for establishing a connection?
  • The TCP three-way handshake involves three steps: first, the client sends a SYN packet to initiate a connection. Then, the server responds with a SYN-ACK packet to acknowledge the request. Finally, the client sends an ACK packet to confirm receipt of the server's response. These steps are important because they ensure that both parties are synchronized and prepared for communication, which reduces the risk of data loss and allows for reliable data transfer.
• Discuss how the TCP three-way handshake relates to session management in network communication.
  • The TCP three-way handshake is fundamental to session management as it establishes a reliable connection before any data is sent. By confirming that both the client and server are ready to communicate and have synchronized their sequence numbers, this process lays the groundwork for orderly data transmission. It ensures that once a session is established, both parties can manage their communication effectively until it is time to terminate the session.
• Evaluate how failures during the TCP three-way handshake can impact network communication and session management.
  • Failures during any stage of the TCP three-way handshake can significantly disrupt network communication. If, for example, the initial SYN packet does not reach the server or if there’s no response from the server's SYN-ACK, the connection will not be established. This can lead to wasted resources and time as retries may occur. Moreover, without an established connection, proper session management cannot take place, leading to potential issues like lost packets or unordered data delivery in applications that rely on TCP for reliable communication.

Related terms

TCP/IP: A set of communication protocols used for the transmission of data over a network, which includes Transmission Control Protocol (TCP) and Internet Protocol (IP).

SYN and ACK: SYN (synchronize) and ACK (acknowledge) are flags used in TCP packets to initiate and confirm the establishment of a connection during the three-way handshake.

Session Layer: The session layer is part of the OSI model responsible for establishing, managing, and terminating sessions between applications over a network.