Computer Network

Concept of LAN, MAN and WAN

Computer network is a set of interconnected computing devices that can exchange data and share various resources with each other. The network devices or nodes are computing devices that need to be linked in the network. Some network devices include computers, routers, switches, gateways etc. A connection in the computer network can be established using either cables or wireless media.

Advantages

  • Sharing of resources
  • Cheaper and faster communication
  • Backup and recovery
  • Great storage capacity

Disdvantages

  • Security issues
  • Rapid spread of computer viruses
  • Expensive setup
  • Requires special technical knowledge

Types of Computer Network

A computer network can be divided into the following types, based on the geographical area, they are:

Local Area Network (LAN)

LAN is the computer network which are connected in a limited area such as school, home and office building. Wires and protocols used in LAN must be of the same type. It is simple and cheaper than other networking systems.

Advantages

  • Data transmission rate speed is faster than MAN and WAN.
  • It is cheaper to establish.
  • You can use the same share software and hardware.
  • It will be easy to manage data at only one place, which makes data more secure.

Disdvantages

  • It is only limited to a small area.
  • Security concerns are big issue.
  • It comparatively connects a small number of computers.

Metropolitan Area Network (MAN)

MAN is the computer network extended up to a city or a larger geographical area than the LAN. Depending upon the type of configuration, this type of network allows you to cover an area from several miles. A cable TV network is an example of MAN.

Advantages

  • It covers a larger area than LAN.
  • It can connect dissimilar systems or networks.
  • It offers fast communication using high-speed carriers, like fiber cables.

Disdvantages

  • Difficult to setup and maintain.
  • It is challenging to manage the network and provide security once it becomes large.
  • You need more cable to establish MAN connection from one place to another.

Wide Area Network (WAN)

WAN is another important computer network that which is spread across a large geographical area. Communication is usually done through satellite, microwave systems or optical fibers. It uses networking devices like routers, gateways, switches, etc. which are more expensive than those used in LAN.

Advantages

  • It covers a larger geographical area than LAN and MAN.
  • It can also connect dissimilar systems or networks.

Disdvantages

  • Data transmission speed is usually slower compared to LAN and MAN.
  • It requires skilled technicians and network administrators.
  • It is comparatively expensive.

Difference between LAN, MAN and WAN

SN LAN MAN WAN
1 It covers small area. It covers about city area. It covers a larger area than LAN and MAN.
2 Easy to setup and maintain. Difficult to setup than LAN and easier tha WAN. It is difficult to setup compare to LAN and MAN.
3 It uses guided transmission media. It uses guided as well as unguided communication media. It uses unguided communication media.
4 Data transmission is faster. Data transmission rate is slower than LAN and faster than WAN. Data transmission is slower than other networks.

Basic Concept of Network Architecture

It is defined as the physical and logical design of the software, hardware, protocols and media of the transmission of data. Based on network architecture, computer network can be classified into:

  1. Peer-to-Peer architecture
    In this architecture, all computers have equal authority to access data and therefore known as peer. Each computer functions as both a client and a server. So there is no dedicated server. This network architecture is a good choice for an environment where there are few computers and users, security is not issue, and centralized control is not needed.

Advantages

  • Simple and easy to setup.
  • If a computer fails, it will not affect others.
  • Any computers can share the resources unlike in client-server architecture where server shares the resources.

Disadvantages

  • Administration of the network is difficult without a dedicated server.
  • Data security is poor in this architecture.
  • Data recovery and backup process are difficult.
  1. Client-Server architecture
    The client-server architecture contains at least one dedicated server and client computers. The server always provides services to clients, and a client always receives services from the server.

Advantages

  • Centralized administration is possible through the network.
  • Appropriate for large organization.
  • Data recovery and backup process is easier.
  • Size of the network can be expanded to any size.

Disadvantages

  • It is expensive due to use of dedicated server.
  • If the server fails, it will affect the network.
  • A specialist network operating administrators are needed.

Difference between Peer-to-Peer and Client-Server Network Architecture.

SN Peer-to-Peer Network Client-Server Network
1 In this type of network there is no specific server. In this type of network, the whole network is divided into the client and server.
2 It is appropriate for small organization. It is appropriate for large organization.
3 It is easier and cheaper to setup and manage. It is complex and expensive to setup and manage.
4 Data management is centralized. Each user has its own data and applications.
5 Highly skilled manpower is not required. Skilled manpower is required.

Some basic terms and tools used in Computer Network

IP (Internet Protocol) Address

IP Address is a unique identifying number assigned to each computing device connected to a network that uses the internet protocol for communication. A typical IP address looks like this: 216.27.61.137
The IP address has two main functions: identifying the network and identifying a particular host (computer) in that network. There are two IP versions: IPv4 and IPv6. The length of IPv4 is 32-bit, and IPv6 is 64 bits.

Subnet Mask

A subnet mask is a number that defines a range of IP addresses available within a network. It uses the same format as an IPv4 address which contains four sections of one to three numbers, separated by dots. Each section of the subnet masks can have a number from 0 to 255. An example of subnet mask is 255.255.255.0

Gateway

The gateway is the computer that routes traffic from a workstation to the outside network with different transmission protocols. For basic internet connections at home, the gateway is the ISP.

MAC Address

MAC (Media Access Control) is known as a physical address and is a unique identifier of each host and is associated with the NIC (Network Interface Card). It is hard-coded onto the computer’s network interface card and is unique. General length of MAC address is 12-digit/ 6 bytes/ 48 bits.

Internet

Internet is a global network of billions of computers and other electronic devices which can access almost any information, communication with anyone in the world, and do much more.

Intranet

It is a private network designed by any organization to support their employees to communicate, collaborate and perform their roles. An example of an intranet is a website that a private company exclusively uses to maintain an employee’s payroll.

Extranet

It is a private network that only authorized users can access. These authorized users may include business partners, suppliers, and even some customers. They can use the extranet to exchange information with each other without having to enter the host company’s main network.

Network tools: Packet Tracer and Remote Login

Packet Tracer is a cross-platform visual simulation tool designed by Cisco Systems that allows users to create network topologies and imitate modern computer networks.

Remote Login is a process where users can log in into a remote site i.e. computer and use their services that are available on the remote computer. The user can access and transfer data from the remote computer to the local computer.

Network Connecting Devices

Network Interface Card [NIC]

NIC is a device that connects the computer and network cable. The cards are installed in an expansion slot in each computer or built into the system. The NIC coordinates the transfer of information between the computer and the network.

MODEM

It stands for Modulator and Demodulator. It is a device that transfers data from binary codes to analog data that can be transmitted over the telephone network and translates analog data into binary codes. Modulation is the process of converting data from digital (binary) to analog, and demodulation is the reverse process.

Hub

It is a device with multiple ports for connecting computers in a star topology. It accepts data, amplifies them, and then broadcasts. It is also used to split segments and propagate signals through them. Its major drawback is it cannot filter network traffic.

Switch

A switch is a data link layer device. It can perform error checking before forwarding data, which makes it very efficient as it does not forward packets that have errors and forward good packets selectively to the correct port only.

Router

The router is used to connect two or more different networks. its main job is to find out the best route (path) that can be used for transmission. In general, routers are responsible for getting traffic along the most efficient possible path from here to there. It operates at the network layer of the OSI model.