TCP/IP Network Model in FE Electrical

Network models are of utmost importance in FE Electrical due to their relevance in the existing world and linkage with other core networking areas in the FE Electrical exam.

This detailed study guide will help you discover how the TCP/IP model in FE Electrical works and transit data between each layer to ensure seamless and secure data connectivity.

Let’s study this important topic of network models in FE Electrical in detail.

TCP/IP Model

The TCP/IP model, also known as the Internet protocol suite, is a conceptual framework for understanding and designing modern digital networks, particularly the Internet.

While the OSI model is a comprehensive, theoretical seven-layer framework for general networking, the TCP/IP model is a more practical, four-layer approach specifically tailored for the internet.

Why TCP/IP Model?

  • Practical and Simplified: TCP/IP is less theoretical and more aligned with the real-world implementation of networks, particularly the Internet. Its four-layer structure simplifies networking concepts, making it easier to understand and implement.
  • Standardization of the Internet: It standardizes procedures and protocols used for communication over the Internet, ensuring interoperability among different hardware and software.
  • Scalability and Robustness: Designed for a vast network (like the internet), it scales well from small local networks to global communication systems. Its decentralized nature enhances robustness and fault tolerance.

Differences from the OSI Model

1. Layer Structure

OSI’s seven layers are more defined and granular, while TCP/IP’s four layers are broader. The OSI model separates functions more distinctly, while TCP/IP combines related functions into fewer layers.

2. Development and Adoption

OSI was developed as a theoretical model to standardize networking systems. In contrast, TCP/IP was developed and refined through practical implementation and usage in ARPANET, the precursor to the Internet.

3. Protocol Specification

The OSI model does not tie itself to specific protocols, making it more of a general guideline. In contrast, TCP/IP is specifically designed around its namesake protocols, TCP and IP.

Purpose of the Four-Layer Model

TCP/IP model inhibits 4-layer architecture compared to the seven layers of the OSI model.

1. Application Layer

  • Combines OSI’s Application, Presentation, and Session layers.
  • Handles high-level protocols, issues of representation, encoding, and dialog control.
  • Examples: HTTP, SMTP, FTP.

2. Transport Layer

  • Corresponds closely to OSI’s Transport layer.
  • Manages end-to-end message delivery in the network, providing reliable data transfer services to the upper layers.
  • Protocols: TCP (for reliable connection-oriented services) and UDP (for connectionless communication).

3. Internet Layer

  • Similar to OSI’s Network layer.
  • Defines IP addressing and routing, determining the path data takes from source to destination.
  • Key Protocol: IP (Internet Protocol), including IPv4 and IPv6.

4. Network Access Layer

  • Merges OSI’s Data Link and Physical layers.
  • Concerns with the physical transmission of data, covering hardware details, media access processes, and physical standards.
  • Not protocol-specific, allowing various network types (like Ethernet, Wi-Fi).

Simply, the TCP/IP model’s effectiveness lies in its practical approach, streamlined structure, and adaptability to the real-world demands of Internet communication. While the OSI model provides a more detailed theoretical framework, the TCP/IP model is directly aligned with the protocols and practices of Internet networking.

Layers of TCP/IP Model

Layers of TCP/IP Model

The TCP/IP model, though commonly referred to as having four layers, can also be discussed in terms of a seven-layer framework that aligns more closely with the OSI model for detailed analysis.

Here’s a deep dive into each layer, their components, modes of transmission, data conversion, protocols used, and security aspects.

1. Link Layer (Network Interface Layer)

Components and Transmission
  • Includes all hardware required for data transmission, such as Network Interface Cards (NICs), switches, and Ethernet cables for wired networks, as well as Wi-Fi routers and protocols for wireless transmission.
  • Responsible for the physical transmission of data over different media (copper wire, optical fiber, wireless, etc.).
  • Deals with MAC addresses for device identification on local networks.
Data Conversion and Protocols
  • Converts binary data into signals and vice versa.
  • Uses protocols like Ethernet, PPP (Point-to-Point Protocol), and ARP (Address Resolution Protocol).
  • Focuses on physical security (protecting hardware from damage or unauthorized access).
  • Implements MAC address filtering and VLAN segregation for network isolation and access control.

2. Internet Layer

Components and Transmission
  • Includes routers and layer three switches.
  • Responsible for logical addressing (IP addresses) and routing packets across networks.
Data Conversion and Protocols
  • Converts transport layer segments into packets (or datagrams) and encapsulates them with an IP header containing source and destination IP addresses.
  • Key protocols include IP (Internet Protocol, including IPv4 and IPv6), ICMP (Internet Control Message Protocol), and IGMP (Internet Group Management Protocol).
  • IPsec (Internet Protocol Security) is implemented for encrypted and authenticated IP packets.
  • Firewalls operate at this layer to filter traffic based on IP addresses and content.

3. Transport Layer

Components and Transmission
  • Primarily software-based, residing in the operating system.
  • Responsible for end-to-end communication and error recovery.
Data Conversion and Protocols
  • Converts application layer messages into segments (TCP) or datagrams (UDP).
  • TCP (Transmission Control Protocol) provides reliable, ordered, and error-checked delivery. UDP (User Datagram Protocol) is used for simpler, quicker, but less reliable transmission.
  • Adds source and destination port numbers in the header for directing traffic to the correct process on the host machines.
  • TLS (Transport Layer Security) and SSL (Secure Sockets Layer) protocols encrypt data at this layer.
  • Can implement port-based security measures, like closing unused ports.

4. Application Layer

Components and Transmission
  • Consists of application software used for network communication, such as web browsers, email clients, and FTP clients.
  • Concerned with high-level protocols and data representation (syntax and semantics).
Data Conversion and Protocols
  • Handles user data using application-specific protocols like HTTP/HTTPS for web browsing, SMTP for email, FTP for file transfers, and DNS for domain name resolution.
  • Operates closest to the end user, translating human-readable data into a format that the underlying layers can process.
  • Application-level security measures like HTTPS (using SSL/TLS), secure email transmission protocols (like PGP), and secure file transfer protocols.
  • Also relies on user authentication, data validation, and access controls.
  • Data Conversion Between Layers

Just like the OSI model, the TCP/IP model also experiences data moves from one layer to the next, it undergoes a process of encapsulation or decapsulation:

Security Across Layers

Each layer in the TCP/IP model plays a distinct role in network communication’s functionality and security, ensuring reliable and secure data transfer from one end system to another over the internet.

  • Link Layer: Focuses on securing the physical network and devices.
  • Internet Layer: Implements security through IPsec and firewall configurations.
  • Transport Layer: Ensures secure transmission with protocols like TLS/SSL.
  • Application Layer: Applies high-level security measures tailored to specific applications and data types.

The Flow of Data Packet in the TCP/IP Model – Step-by-Step Process

The TCP/IP model’s packet flow is central to understanding how data is transmitted over the internet. Let’s see how packets flow over the internet between each TCP/IP Model layer.

Top to Bottom Flow (Application to Link Layer)

1. Application Layer

Flow: Data generation and preparation for transmission using protocols like HTTP, SMTP, and FTP.

Stopped: If the data is malformed or the application encounters an error (e.g., invalid request, authentication failure). Security measures (like input validation and authentication checks) can also halt suspicious or unauthorized data.

OSI Difference: Corresponds to the OSI model’s Application, Presentation, and Session layers, combining their functionalities.

2. Transport Layer

Flow: Segmentation of data into smaller units (TCP segments or UDP datagrams), adding port numbers for communication endpoints.

Stopped: Due to errors in segment/datagram creation, congestion, or unreachable ports. Security measures like firewalls might block certain ports to prevent unauthorized access.

OSI Difference: Very similar to the OSI model’s Transport Layer, with the same primary functions.

3. Internet Layer

Flow: Packet creation with IP headers, including source and destination IP addresses and routing of packets.

Stopped: If the destination IP is unreachable, routing fails, or due to IP address filtering. Firewalls at this layer prevent unauthorized network access and data breaches.

OSI Difference: Similar to OSI’s Network Layer but more focused on IP-based routing.

4. Link Layer

Flow: Encapsulation of packets into frames with physical addresses (MAC addresses), preparing for physical transmission over the network medium.

Stopped: Physical transmission issues, MAC address filtering, or hardware errors. Security at this layer includes physical access control and MAC address filtering.

OSI Difference: Combines OSI’s Data Link and Physical layers, addressing both data framing and physical transmission.

Bottom to Top Flow (Link to Application Layer)

1. Link Layer

Flow: Reception of frames, decapsulation to extract packets, and passing them to the Internet layer.

Stopped: Corrupted frames, physical layer issues, or MAC address mismatches. Ensures only correctly formatted and destined frames are processed.

OSI Difference: Handles both frame reception and physical signal conversion, unlike OSI’s separate Physical and Data Link layers.

2. Internet Layer

Flow: Packet processing, including IP address verification and routing to the appropriate destination (next-hop or final destination).

Stopped: IP conflicts, routing errors, or firewall policies blocking the packet. Ensures that packets follow correct routing paths and meet security policies.

OSI Difference: Similar to OSI’s Network layer, with a strong focus on IP-based routing.

3. Transport Layer

Flow: Reassembling segments/datagrams into complete messages, error checking, and delivery to the Application layer.

Stopped: Missing segments, checksum errors, or security policies (e.g., firewall rules on ports). Ensures data integrity and adherence to communication protocols.

OSI Difference: Parallel to OSI’s Transport layer in function and security mechanisms.

4. Application Layer

Flow: Processing of data by the appropriate application based on port numbers.

Stopped: Application-level errors, unsupported protocols, or security blocks (e.g., web filters, email spam filters). Ensures data is usable and secure for applications.

OSI Difference: Encompasses the functionalities of OSI’s top three layers, integrating application processing, data presentation, and session management.

Impact on Security Due to Certain Layer’s Posture

Each TCP/IP model layer has distinct security responsibilities, from ensuring secure application data transactions to controlling physical network access. 

  • Application Layer: Focus on data validation, application-specific security (e.g., HTTPS), and access controls.
  • Transport Layer: Implement secure transmission protocols (TLS/SSL), manage port security, and monitor for unusual traffic patterns.
  • Internet Layer: Use firewalls for IP filtering, implement IPsec for secure IP communication, and manage routing policies.
  • Link Layer: Physical network security, MAC address filtering, and monitoring for physical layer anomalies.

Read the other part of this guide here to understand how the OSI model works and why it’s an important network model in the FE Electrical exam.


Now you understand how different TCP/IP model layers communicate and share information to ensure a seamless and secure data flow. You can use this framework study to manage data security and optimization effectively.

It allows for threat prevention at each level of architecture in the network hierarchy. For an effective FE Electrical exam preparation, we recommend you check our comprehensive study resources, guides, and preparation courses at Study for FE – your go-to place for all things FE-related.


Licensed Professional Engineer in Texas (PE), Florida (PE) and Ontario (P. Eng) with consulting experience in design, commissioning and plant engineering for clients in Energy, Mining and Infrastructure.