TCP/IP Model Explained: Layers, Functions

The TCP/IP reference Model

Introduction

The TCP/IP model is the foundation of internet communication. It defines how data is sent, routed, and received over a network. This model is simpler than the OSI model, using just four layers instead of seven.

TCP/IP Ref Model

Application

Transport

Internetwork

Host-To-Network

 

1. Application Layer

• Handles protocols like HTTP, FTP, SMTP, DNS
• Interfaces directly with user applications

2. Transport Layer

• Manages end-to-end communication
• Uses TCP (reliable) or UDP (faster, connectionless)

3. Internet Layer

• Handles addressing and routing of packets (IP protocol)
• Routers operate at this layer

4. Network Access Layer (Link Layer)

• Deals with the physical transmission of data
• Includes hardware-level protocols like Ethernet, ARP

TCP/IP Model VS OSI Model

TCP/IP Model	OSI Model
7 Layers	4 Layers
Conceptual model	Practical implementation
Developed by ISO	Developed by DARPA
Layers are strict	Layers are flexible

 

The Well Known Ports Used by TCP

Port	Protocol	Use
21	FTP	File Transfer
23	Telnet	Remote Login
25	SMTP	E-Mail
69	TFTP	Trivial File Transfer Protocol
79	Finger	Lookup information about a user
80	HTTP	World Wide Web
110	POP-3	Remote e-mail access
119	NNTP	USENET news

 

Electronic Mail:

Electronic mail is a method for communicating message electronically using computer networks.
A way of sending message between people anywhere within an organization or in the world using a computer that can communicate with another computer through a computer network. The message or document can be viewed on a computer screen and printed out. 

Ethernet:

A local area network (LAN) protocol that supports data transfer.

Firewall:

A firewall is a technique used in a secured computer system or network to block unauthorized access and allow only the authorized user. Firewalls can be implemented in either hardware or software, or a combination of both.

 

Cookies:

A cookie (also known as a web cookie, browser cookie, and HTTP cookie) is a small bit of text or a file that accompanies request and page as they go between the web server and browser.

 

Digital Signature:

Digital signatures allow us to verify the author, date and time of signatures, authenticate the message contents. It also includes authentication function for additional capabilities.

 

Digital Certificate:

A digital certificate (also known as a public key certificate or identity certificate) is an electronic document which uses a digital signature to bind together a public key or password required for encoded and encoded document with an authentic identity such as the name of person or an organization, their phone numbers or address, and so forth.

If you're also learning about the OSI model, check out our guide on the OSI Reference Model and Its 7 Layers.