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

Digital Transmission

Line Coding

Digital signal is converted in the digital data that process is known as the Line Coding. That data is stored in the computer in the form of text, audio, video, numbers, and graphical images as the sequence bits. In the line coding, the sequence of bits is converted into the digital signal. Digital data is converted into a digital signal at the sender. Digital data is retrieved by decoding the digital signal at the receiver. There are shows in the figure below.

Digital Transmission

Line coding schemes

Line coding schemes are divided into five different types:

1. Unipolar

2. Polar

3. Bipolar

4. Multilevel

5. Multitransition

Digital Transmission

Unipolar Scheme

In this scheme, all signal levels occur on one side of the time-axis, either up or down.

NRZ (Non-Return to Zero): The unipolar scheme was mainly designed to non-return-to-zero (NRZ) in which 1 bit defines the +ve voltage, and 0 bit defines the zero voltage. The unipolar scheme NRZ shows in the diagram below.

Digital Transmission

Polar Scheme

In this scheme, the voltages occur on both sides of the time axis. For example, If the voltage level is 0 (zero), it can be positive, and if the voltage level is 1 (one), it can be negative.

NRZ (Non-Return to Zero): There are two versions of NRZ in the polar schemes: NRZ-L and NRZ-I. NRZ-L stands for NRZ-Level. In the first version of NRZ, the value of the bit is determined by the level of the voltage. NRZ-I stands for NRZ-Invert. In the second version of NRZ, the value of the bit is determined by the change in the level of voltage. If there is no change in the value of the bit, then the bit is 0, and if there is a change in the value of the bit, then the bit is 1.

N/2 Bd is the average signal rate for both NRZ-L and NRZ-I. DC component problem is in both NRZ-L and NRZ-I.

Digital Transmission

RZ (Retune to Zero): The key issue with NRZ (Non-Return to Zero) encoding occurs when the clocks of the sender and receiver are not synchronized. The receiver does not know when one-bit finishes, and when the next bit begins. The RZ (return-to-zero) scheme is one solution, which uses three values: positive, negative, and zero. Positive voltage represents for 1, Negative voltage represents for 0, and Zero voltage for none.

Digital Transmission

Biphase (Manchester and Differential Manchester)

Manchester scheme is a mixture of the RZ and NRZ-L scheme.

Differential Manchester scheme is a mixture of the RZ and NRZ-I scheme. Manchester and Differential Manchester is minimum bandwidth two times greater than the NRZ.

Digital Transmission

Bipolar Schemes

Bipolar scheme sometime is called the multilevel binary. The NRZ is an alternative to the bipolar scheme. It was developed in the later of NRZ.

In this scheme, there are three voltage levels: +ve (positive), -ve (negative), and 0. At zero, it is one data element of the voltage level, while another component of the voltage level alternates between positive and negative. There are two variations of the bipolar scheme one of the AMI and another pseudoternary.

AMI and Pseudoternary: The full form of AMI is Alternate Mark Inversion, and it is a standard bipolar encoding scheme. Variations of AMI encoding is referred to as the Pseudoternary. Both the AMI and Pseudoternary are shown in the diagram below.

Digital Transmission

Transmission Modes

The transmission mode decides how to data is transferred between one device to another device. It can transfer the data to two different modes: Parallel and Serial. Types of the transmission mode are shown in the below diagram.

Digital Transmission

Parallel Transmission

In the Parallel transmission, n bits are sent by n communication lines at a time. If you want to send the n bits, then you will use the n lines. The main advantage of parallel transmission is the high-speed transfer of the data. The main disadvantage of parallel transmission is that it covers short distances. It is very expensive because the n communication lines transmit n bits of data. Parallel transmission is shown in the figure.

Digital Transmission


Serial Transmission

In Serial Transmission, n bits of data are transmitted one by one in the sequence. The serial transmission uses only one line to transmit the data between the sender and the receiver. It is used in the telephone lines. The main advantage of serial transmission is that it is very cheaper. The main disadvantage of serial transmission is that its speed is very low because the data is transmitted in the sequence. Serial transmission is shown in the figure.

Digital Transmission

Type of Serial Transmission

1. Asynchronous Serial Transmission

2. Synchronous Serial Transmission

3. Isochronous Serial Transmission


In the asynchronous transmission, only one character is sent at a time, whether it is a number or alphabet. It sends a start bit at the beginning and sends one or more stop bits at the end of each byte, as shown in the diagram below.

Digital Transmission


In the synchronous transmission, the data is sent in block format at a time, and each block has a lot of characters. It sends the bits one by one without any start or stops bits or gaps, as shown in the diagram below.

Digital Transmission


In the isochronous transmission, the data arrives at a fixed rate. Isochronous transmission is a mixture of the asynchronous and synchronous features.