TCPIPstapel

TCPIPStapel, commonly referred to as the TCP/IP stack, is a collection of communication protocols used for Internet and similar networks. It governs how data is packetized, addressed, transmitted, routed, and received across multiple interconnected networks. The architecture is commonly described as four layers: Link, Internet, Transport, and Application. While sharing some concepts with the OSI model, the TCP/IP model has distinct boundaries and protocol sets.

The Link layer covers the local network technology and interface hardware, such as Ethernet and Wi‑Fi, including address resolution and frame transmission. The Internet layer handles logical addressing and routing, most notably the Internet Protocol (IPv4 and IPv6), along with ICMP for error messages and diagnostics and IGMP for multicast support. The Transport layer provides end‑to‑end data transfer services, with TCP delivering reliable, connection‑oriented communication featuring a three‑way handshake, sequencing, and congestion control, and UDP offering a lighter, connectionless service with lower overhead. The Application layer comprises protocols used by applications, such as HTTP/HTTPS, DNS, FTP, SMTP, SSH, and TLS, which run atop the transport layer.

Key features include end‑to‑end delivery, IP addressing and routing, fragmentation and reassembly, and error reporting. Security is implemented at multiple levels, notably through TLS/DTLS within application protocols, while NAT, DHCP, and other utilities aid deployment and maintenance. TCP/IP stacks are implemented in operating systems, embedded systems, and network devices; common implementations include kernel‑level stacks in Linux, Windows, and BSD, as well as lightweight stacks like lwIP for embedded systems. The stack originated in the 1970s–1980s and underpins the modern Internet.