network topology is defined as: the schemes of joining a number of
computers in the form of a network are called Network Topologies.
Physical Transmission media
In physical Transmission media, communication devices are directly
linked with each other via cables or other physical materials for data communication.
It is one of the most commonly used communication media for network cabling.
It consists of two separate copper wires that are covered by insulating
material such as plastic and twisted together to form a cable.
Coaxial Cable is also referred to as coax. It consists of a single copper
wire surrounded by insulating materials. Usually, it is surrounded by three layers.
Solid metal shield
External plastic cover
In twisted-pair cable and coaxial cable, data is transmitted in the form
of electric frequencies. So copper wire has to be protected from water
and electromagnetic waves. In fiber optic cable, these types of problems
are not occurred. The fiber-optic cable uses light to transmit data.
A fiber-optic cable consists of hundreds of thin glass fibers or
strands of glass. Each strand is referred to as optical cable.
In Wireless transmission media, communication devices communicate
with each other and data is communicated through the air or space
using broadcast radio signals, microware signals and infrared signals.
This transmission medium is used when it is impossible to install the cables.
The data can be transmitted all over the world through this medium.
It is a wireless transmission medium that is used to communicate information through radio signals in air, over long distance such as between cities and countries. In this medium, a transmitter is required to send messages and receiver is required to receive them. To receive the broadcast radio signal, the receiver has an antenna that is located in the range of signal. Some networks use a special device called transceiver used to send and to receive messages in the form of radio signals. The data transmission speed of broadcast radio is up to 54 Mbps.
Cellular radio is a form of broadcast radio that is used for mobile communication such as cellular and wireless modems. A cellular telephone is a telephone device that uses high frequency radio waves to transmit voice and digital messages. Some mobile users connect their laptop computer or other mobile device to a cellular telephone to access the web, send and receive email while away from a standard telephone line.
Microwaves are radio waves that provide a high speed transmission. In microwaves transmission, data is transmitted from one station to another. Microwaves station contains an antenna, transceiver and other equipments that are required for microwave communication. The data transmission speed of microwave transmission is up to 150 Mbps.
Digital Modem The modem that is used to send and to receive data to and from a digital telephone line is called digital modem. ISDN modem and DSL modem are the best example of digital modem. These modem are used to send and receive the digital data to and from the digital line, So there is no need to convert to analog signals because digital lines already use the digital signals.
It is an electronic device that connects two same type of networks and control the traffic between them. A bridge basically split an overloaded network into two separate network for reducing the amount of traffic on each segment and increase the performance of each network. A bridge looks at the information in each packet header and forwards data from one LAN to another.
An electronic device that connects many computers together and transmits data to its correct destination using the available path on the network is called router. It stores the information of each node on the network and to use these information to transfer date between nodes.
A gateway is an electronic device that can perform logical function. A gateway is a device or system (because it may be a hardware or software) that connects two or more networks to share their information from one to the other. Packets from different networks have different type of information in their headers, and information in different format. The gateway can take a packet from one type of network, read the header, and then encapsulates the entire packet into a new one, adding a header that is understood by the network.
DNS (Domain Name System)
A Domain Name System (DNS) is the method that the internet uses to store domain names and their corresponding IP addresses. In other word DNS resolves the host or domain name to IP addresses. Each domain name is associated with a IP address like 126.96.36.199 four set of digit separated by dots.
Asynchronous Transfer Mode (ATM)
Asynchronous Transfer Mode is an advanced data transmission way. It is very fast and reliable data transmission connection line that can carry data, audio, video, imaging and multimedia transmission etc.
ROUTER AND ROUTING
A Router is an electronic device that used to connects multiple computers, networks together and transmits data to its correct destination using the available path on the network is called router. You can say a router choose the best path for data transfer on available paths.
IP stands for internet protocol. Basically it is a unique identifier for a computer on the internet. It is numerical address with four numbers separated with dots and the format of an IP address is a 32-bit.Each number can be start from 0 and ends with 255. For example IP address looks like this: 188.8.131.52
The DSL stand for Digital Subscriber Line. DSL provides high speed on already exiting telephone lines and same time you can use internet and as well as your line for phone. In DSL, both ends of connections require the network cards and DSL modems for data communication.
ADSL stand for asymmetric digital subscriber line, here asymmetric means data speed does not same in both directions (upload and download) and provides high speed on already exiting telephone lines and same time you can use internet and as well as your line for phone.
The transfer of data from one place to another place in the form of digital signals and this data is broken into small data segment before being transmitted from one computer to another computer. These small data segments are called packets.
VOIP stand for Voice over Internet Protocol, in common terms voice connection using internet protocol through internet. In technical words VOIP is a technology used to transmit voice using broadband internet connection instead of old analog phone lines.