TCP/IP Model Reference

The 4 TCP/IP layers with OSI mapping and example protocols.

TCP/IP Layer	OSI Mapping	Example Protocols	Role
Application	OSI 5–7	HTTP, DNS, SMTP, FTP, SSH, DHCP	User services and application data.
Transport	OSI 4	TCP, UDP	Ports, segments, reliability vs speed.
Internet	OSI 3	IP, ICMP, IGMP	Logical addressing and routing.
Network Access (Link)	OSI 1–2	Ethernet, ARP, Wi-Fi	Physical framing and LAN delivery.

How to read the result

TCP/IP merges OSI's top three layers into Application and bottom two into Network Access. Internet and Transport map 1:1 to OSI L3/L4.

Transport ≈ OSI L4 → TCP/UDP ports and segments.

Application covers OSI 5–7, Transport is OSI 4, Internet is OSI 3, Network Access covers OSI 1–2.

Internet layer (OSI Layer 3). TCP and UDP sit one up, at Transport.