Computer Network Tutorial

Introduction of Computer Network Types of Computer Network Network Topology Computer Networking Architecture Transmission Modes (Data Flow) Basic Networking Devices Integrate Services Digital Network (ISDN)


OSI Model TCP/IP Model

Physical Layer

Digital Transmission Analog Transmission Transmission Media Switching

Data Link Layer

Error detection and Error correction Data Link Control Multiple Access Aloha

Network Layer

Network Layer - Logical Address Address Mapping Unicast Routing Protocol

Transport Layer

Process to Process Delivery User Datagram Protocol Transmission Control Protocol Stream Control Transmission Protocol Session Layer and Presentation Layer

Application Layer

Domain Name System Application Protocol E-mail Cryptography


Classes of Routing Protocols Classification of Routing Algorithms Controlled Access Protocols in Computer Networks Differences between IPv4 and IPv6 Fixed and Flooding Routing Algorithms Advantages and Disadvantages of Fibre Optics Cable APIPA Difference between Active and Passive FTP Fiber Optics and its Types Method of Joining and Fusion of Fiber Optic Cable Define Framing in Computer Network Disadvantages of Computer Network Mesh Topology Diagram in Computer Network Ring Topology in Computer Network Star Topology in Computer Networks 4G Mobile Communication Technology Advantages and Disadvantages of LAN Advantages and Disadvantages of MAN Advantages and Disadvantages of WAN Application Layer in OSI Model Cyclic Redundancy Check Example Data link layer in OSI model Difference between Transport and Network Layer Hamming Code Example Network Layer in OSI Model Session Layer in OSI Model Transport Layer in OSI Model Two Port Network in Computer Networks Uses of Computer Networks What is Computer Network What is Framing in a Computer Network Advantages and Disadvantages of Bus Topology Difference between Star Topology and Bus Topology Subnetting in Computer Network Subnetting Questions and Answers What is Bus Topology What is Network Topology and Types in Computer Networks Access Control in Networking Basic Characteristics of Computer Network Benefits of SOCKS5 Proxy in Computer Networks Computer Network viva Questions Difference between BOOTP and RARP Difference Between Network Topologies and Network Protocols Difference between NFC and RFID Difference Between Point-to-Point Link and star Topology Network Differences Between MSS and MTU Differences Between Trunk Port and Access Port Different Modes of Communication in Computer Networks MIME Protocol in Computer Networks Modes of Communication in Computer Networks Network Attack in Computer Network Port Address in Networking Simplest Protocol in Computer Network Sliding Window Protocol in Computer Network Stop And Wait Protocol in Computer Networks TCP 3-Way Handshake Process in Computer Networks What is a Proxy Server What is APPN What is ICMP Protocol What is Point-to-Point Protocol What is Port Address in Networking What is the HDLC Protocol What is VRRP Protocol Difference Between Analog and Digital Signals Difference Between Hub and Repeater Difference between Repeater and Switch Difference Between Transparent Bridge and Source Routing Bridge Source Routing Bridge in Computer Networks Transparent Bridge in Computer Networks Transport Protocol in Computer Networks Types of CSMA in Computer Networks What is Wired and Wireless Networking Network Security in Computer Network Disadvantages of Extranet Difference Between TELNET and FTP Define Protocol in Computer Networks Guided Transmission Media in Computer Network What is a Gateway in a Computer Network IGMP in Computer Networks LAN Protocols in Computer Networks MAN Meaning in Computer Modulation Techniques in Computer Networks Switching in DCN TCP/IP Applications What is IGMP? What is Modem in Networking What is Non-Persistent CSMA Difference between Cell Splitting and Cell Sectoring Forouzen Computer Network

Network Layer in OSI Model

This article will help you in getting a good understanding of the Network Layer in the OSI model.

The network layer is the third layer of the OSI Model from the bottom. The network layer is mainly responsible for controlling of delivery of data from source to destination via multiple nodes.

The network layer consists of various networking protocols for sending data(in the form of packets) from one network to another network. A few networking protocols are Internet Protocol(IP)(IPv4, IPv6), User Datagram Protocol(UDP), File Transfer Protocol(FTP), Hyper Text Transfer Protocol(HTTP), etc.

The information/data(data packets) which is routed from source to destination contain the source address and the host address of the receiver. If we speak non-technically the network layer finds out the shortest and easier path between source and destination with the help of various routing, and switching techniques. It utilizes subnetting designs and logical network addressing for transferring the data packets from source to destination.

The function of this layer is only to route the data packets from source to destination whether the source and destination may present in different networks and use different protocols. This routing can be achieved with the help of logical IP addressing and routers.

IP Addressing:

The IP address is a 32-bit numerical value that is used to uniquely identify a device in a network. It consists of 2 components they are network and host address. The network part determines the type of network assigned to the data and the host part is helpful in uniquely identifying the device in the network. It generally represented in a dotted-decimal format.


A router is a network device that receives, analyses, and routes the data packets to the destination. Routers are used in LAN(Local Area Network) and WAN (Wide Area Network)networks. It uses various routing protocols for sending the data across various networks.

Functionality of Network Layer

To maintain the connection between different networks the network layer is used. It helps the networks to be connected.

We can transfer the data using either the connection-oriented way or the wireless way. The network layer can only transfer the data using either one of these two ways. It is also helpful during the movement of data bits between network parts or segments.

As we all know network layer is said to be situated in between the transport layer and data link layer, it is used to transfer the data from transport to data link layer. Whenever, there is a necessity of data to be transferred the network layer is said to be receiving the data from the transport layer. The data which is received is sent in a bulk form which means the data has no divisions instead all the data is sent as a single pack.

To separate the data into segments and send it further to the network layer is the only solution to be existing. The network layer not only transports the data but also divides the whole data among different segments and seals them into different packets and then formulates the sets or frames of data to the forwarding layer which is the data link layer.

The network layer is said to be even dictating the path for the data to be transferred. It determines the data to traverse through a particular physical path. Such a decision is taken by the network layer only when there are multiple paths for the data to be transferred.

The functions of the network layer can be classified into three various types. The first functionality is named to be addressed. It addresses different sets of data with a unique number to identify wherever it may be present in the whole set of data or not.
Further functionality can be entitled as internetworking which is said to be one of the vital tasks and responsibilities of the network layer. Internetworking is nothing more of a complicated task instead it is the process of arranging the connection between the networks.
And, the third functionality is routing where the network layer optimizes a best route among different routes for the data to get transferred. To discuss the next functionality there is a need to be gaining an idea of a special term which is known as Internet Protocol. It is a layer named network layer protocol. It helps the network layer to perform a functionality known as packetizing. In packetizing, the received packets or frames of data from the upper layer are summed up and made into new frames of data.