Layers

Network Layers

  • A network model describes how different network protocols interact and work together to provide network services.
  • Layers in a network model organize the communication system into smaller parts to simplify the components, making them easier to understand and implement.

Key Layers in the TCP/IP Model

  • The Application Layer: This layer is responsible for network services to applications. It marks the data with application specific details before passing it to the transport layer. Examples of application layer protocols are HTTP, FTP and SMTP.

  • The Transport Layer: The transport layer is responsible for data transmission between devices. It controls the reliability, flow control, and error checking. It breaks data into small packets for transit across the network. Two main protocols are used at this layer: TCP and UDP.

  • The Internet Layer: This layer handles the movement of packets around the network. It uses the IP protocol to deliver packets based on IP addresses. Other key protocols used at this layer include ICMP and IGMP.

  • The Network Access Layer (also called the Link Layer or Network Interface Layer): This layer is responsible for the hardware addressing (MAC addresses) of packets and the physical transmission of data. This process includes protocols that operate on a network’s layout such as Ethernet and Wi-Fi.

Importance of Network Layers

  • Simplification: Network layers break the complex process of communication over a network into more manageable parts, simplifying the overall process.

  • Interoperability: Network layers allow interoperability between different software and hardware systems, as each layer has a specific purpose and interacts with the layers above and below it in a consistent and standardized way.

  • Easier troubleshooting: Having a layered network model allows easier identification and troubleshooting of network issues, as each layer has a specific focus.

Encapsulation and De-Encapsulation

  • Encapsulation occurs when data is passed from higher layers to lower layers. Each layer adds its own header (and sometimes a footer) to the data it receives from the layer above it, in a process called ‘data encapsulation’.

  • De-encapsulation happens at the receiver side where headers added by each layer are stripped off to get the actual data.