MSDN Documentation

TCP/IP Protocol Suite

The Transmission Control Protocol/Internet Protocol (TCP/IP) suite is a set of communication protocols used to interconnect network devices on the internet and other computer networks. It is the most widely used protocol suite today, forming the foundation of the internet and most private networks.

Overview

TCP/IP is a layered protocol, meaning that it is divided into several layers, each responsible for a specific set of functions. This layered approach provides flexibility and allows different protocols to be developed and used independently. The most common model for TCP/IP is the four-layer model:

1. Application Layer: This layer provides network services directly to user applications. Examples include HTTP, FTP, SMTP, and DNS.
2. Transport Layer: This layer provides reliable or unreliable data transfer between processes running on different hosts. The two main protocols are TCP (Transmission Control Protocol) for reliable, connection-oriented communication, and UDP (User Datagram Protocol) for unreliable, connectionless communication.
3. Internet Layer (or Network Layer): This layer is responsible for addressing, routing, and packaging data packets. The primary protocol here is IP (Internet Protocol).
4. Network Access Layer (or Link Layer): This layer handles the physical transmission of data over the network medium. Protocols like Ethernet and Wi-Fi operate at this layer.

Key Protocols

Transmission Control Protocol (TCP)

TCP is a connection-oriented protocol that ensures reliable data delivery. It achieves this through:

• Connection Establishment: Uses a three-way handshake to establish a connection before data transfer.
• Sequencing and Acknowledgement: Data is segmented, sequenced, and acknowledged to ensure it arrives in order and without errors.
• Flow Control: Prevents a fast sender from overwhelming a slow receiver.
• Congestion Control: Manages network traffic to avoid congestion.

TCP is suitable for applications that require reliable data transfer, such as web browsing (HTTP), email (SMTP), and file transfer (FTP).

User Datagram Protocol (UDP)

UDP is a connectionless protocol that prioritizes speed over reliability. It offers minimal overhead and does not guarantee delivery, order, or error checking beyond a basic checksum.

UDP is used in applications where speed is critical and some data loss is acceptable, such as streaming media, online gaming, and DNS queries.

Internet Protocol (IP)

IP is the protocol responsible for addressing and routing packets across networks. It defines:

• IP Addressing: Assigns unique IP addresses (IPv4 and IPv6) to devices.
• Datagram Packet Format: Defines the structure of IP packets.
• Routing: Determines the best path for packets to travel from source to destination.

Common TCP/IP Applications

• HTTP/HTTPS: For web browsing.
• FTP: For file transfer.
• SMTP/POP3/IMAP: For email communication.
• DNS: For resolving domain names to IP addresses.
• SSH: For secure remote login.

Network Configuration Example (Conceptual)

Here's a simplified view of how data might flow:

// Client requests a web page
// Application Layer (HTTP) creates a request

// Transport Layer (TCP) segments the request, adds port numbers (e.g., 80 for HTTP)
// and establishes a connection with the server.

// Internet Layer (IP) adds source and destination IP addresses to each segment.
// Packets are routed across the internet.

// Network Access Layer (Ethernet) encapsulates IP packets for transmission
// on the local network.

// Server receives the packets, reassembles the data (TCP),
// and passes the HTTP request to the web server application.
            

Further Reading

• RFCs (Request for Comments)
• Understanding IPv4 and IPv6
• Winsock API Reference