Networking Devices
Networking devices are electronic equipment's which are required for interaction between devices across the computer network.
In other way we can say; hardware devices those are used to connect computers, laptops, printers and other electronic equipment to a network are known as network devices.
Therefore; Networking devices are itself the medium for transferring computer data from one node to another node over the network.
There are many Networking devices and we will discuss about most important of those.
Let us understand one by one in this lecture to following.
Network Adapter
The primary network hardware that is required to be available in all computers, laptops and printers for being connected to a network is the network adapter or we may say network interface card or it is also known as LAN card.
Network Adapter connects one computer to other computers across the network. Generally it comes inbuilt and embedded with the networking devices like computers, laptops and printers but it is also available separately in the market. It can be connected in additional slots available in some motherboards for having extra option of LAN interface in a system.
RJ45 Connector
RJ45 connectors are generally available with eight-pin that is the standardized interface which often connects computers and printers to a local area network. These types of connectors are developed for both telephone communications as well as for computer network connectivity. The similar types of dedicated connectors that are used for telephone connections are known as RJ11 connectors. The RJ45 has eight copper small pointer head which comes in contact with the copper wire while the Ethernet cable is inserted and crimped inside the RJ45 connectors. So the signal can be transmitted through the either side of the Ethernet cable having connected with RJ45 in both ends. The RJ45 connector is connected to the network adapter of computer or other devices in order to receive and send data packets over the network.
Networking Cables
Let us start the discussion about network cables.
Networking cables are physical long and thin in shape with round diameter networking hardware used to connect one network device to other network devices. It is commonly used to connect two or more computers in a network to share its resources, printers & etc.
Networking cables are a type of networking hardware used to connect a network device to one or more other network devices, or to connect two or more devices to a single computer or network device.
There are four types of network cabling; let us discuss those one by one.
Coaxial Cable
If we closely observe the coaxial cables then we will observe a single copper conductor at the center of it where a plastic layer provides insulation between the center copper wire and the copper mesh shield; which is further protected by outside insulation.
This mechanism of coaxial cabling helps to eliminate signal obstruction but it is a complex process to install. It can cover longer cable distances between network devices. There are two types of coaxial cables; one is thick coaxial cable and the other is thin coaxial.
Fiber Optic Cable
Let us discuss about fiber optic cables; it is also known as an optical-fiber cable; it contains one or more optical fibers that are used to carry light and it possess a center glass core surrounded by multiple layers of protective materials. This mechanism avoids electrical obstruction because instead of passing electronic signals optical-fiber cable transmits data as pulses of light through flexible, optically pure fibers of glass or plastic and this makes the process fast data transmission speeds over long distances.
Shielded Twisted Pair (STP) Cable
Let us discuss about the shielded twisted pair cable; it is a special kind of copper local area network wiring and it is commonly used in small network setup. Two insulated copper wires are twisted around each other to reduce electromagnetic induction between pairs of wires that is why it is known as twisted pair.
Unshielded Twisted Pair Cable
Now Let us discuss about the unshielded twisted pair cable; UTP cables are mostly used for LAN that is local area network setup with limited area coverage having some computers, printer and other devices connected together in order to share resources among them. This cables consisting of four or eight thin copper wire insulated with plastic cover having separate colors of plastic coted copper wires inside it. In this cabling two copper wire of a single circuit are twisted together for the purposes of improving electromagnetic compatibility.
Modem
Modem is a networking device that enables a computer to send and receive data over the telephone and the cable lines. We know that the data understood by the computer is digital whereas the telephone line or cable wire can only transmit analog data. Therefore the modem plays vital role to convert digital signal into analog and analog signal into digital.
Modem is a combination of two devices:
One is modulator and other one is demodulator.
When the data is being sent by the computer across the network then the modulator converts digital data into analog data as only the analog signal can be transferred through the telephone line or cable wire.
When the data is being received by the computer over the network then the demodulator converts analog signals into digital data because our computer understand only digital data.
Types of Modem
Let us discuss different types of modem one by one.
In several ways the modem can be categorized; such as type of connections to the transmission line, direction in which modem can transmit data, transmission mode and there are many more ways to categorizer the functionalities of modem.
Let us discuss about some very common types of modem those are used in our regular life depending on direction of the data transmission.
Simplex Modem: The simplex modem can transfer data in only one direction that is either from digital device to network setup using the modulator process that is digital data into analog signal or from the network setup to the digital device using the demodulator mechanism that is analog signal to digital data.
Therefore the simplex modem cannot work with both modulator and demodulator; that is why it does not support two way conversions.
Half Duplex Modem: The half-duplex modem can transfer data in both directions from digital device to network setup using the modulator process that is digital data into analog signal and from the network setup to the digital device using the demodulator mechanism that is analog signal to digital data.
Therefore the half-duplex modem can work with both modulator and demodulator; that is why it supports two way conversions but it performs only one process at a time. Other process will not start its operation unless the current process is fully completed.
The example of a half-duplex modem is walkie-talkie. We have observed that traffic polices use walkie-talkie to control traffic regulation in road.
In walkie-talkie two traffic officers cannot participate together at same time one officer has to wait until the other officer completes sending verbal message.
Full Duplex Modem: The full duplex modem is different from the half-duplex modem it can transmit data in both directions simultaneously at same time unlike the half-duplex modem that we have discussed before; it transmits data from digital device to network setup using the modulator process that is digital data into analog signal and from the network setup to the digital device using the demodulator mechanism that is analog signal to digital data.
Therefore the full-duplex modem can work with both modulator and demodulator as same as in the half-duplex modem; that is why it supports two way conversions but it performs both processes simultaneously at same time unlike the half-duplex modem where in half-duplex modem other process has to wait unless the current operation is fully completed.
The example of the full-duplex modem is a telephone call where both parties can communicate at the same time across different parts of the world whereas in Half duplex; if we compare with a walkie-talkie conversation where the two parties wait for their turns to come for speaking to each other.
Network HUB
Let us understand about the networking hub.
Hub is a networking device that broadcasts data to all actively connected computers and other networking devices in a network. Hubs cannot identify any specific device over the network for sending and receiving data packets because it operate by forwarding packets across all live ports over a network where only the intended receiver will accept the data packets and other nodes will reject the same. In this way hubs make the network congested and the bandwidth speed is also divided by the number of active ports connected to a network.
Therefore; to build a large network hub is not suitable to use because with the increase in computers over a network will result to sharing bandwidth of the device and making the network more congested.
Network Switch
Now let us understand about the networking switch.
Switch is a networking device that connects computers and other devices on a network by using a technique commonly known as packet switching to forward and receive data packets to the destination device. Switch is a multiport network bridge that can identify the exact destination device to forward data over the network by knowing the MAC addresses of all devices connected to a switch. Switch work at data link layer of OSI model to forward and receive data in a network.
Switch has a MAC table which records all MAC address of networking devices that are connected to it for the corresponding port number and that helps to identify the intended device for sending packets to it over the network. Unlike the hub switch does not makes the network congested by broadcasting data to every nodes in a network and it uses full bandwidth speed to forward data to the destination device as switch only send data to single intended destination.
Normal switches works in data link layer of OSI model hence it cannot communicate data packets between two or more different networks but manage switch is a layer three device that is more like the router and manage switch works on both data link layer as well as network layer that is why it can communicate between two or more networks like the router.
Router
Now let us understand about the router.
Router is a networking device that connects two or more networks which routes network packets based on their IP addresses to other network devices. It forward data packets to the intended IP addresses and in this way it manages traffic between these networks and it also allows multiple devices to use the same Internet connection.
Router works at network layer of OSI model; so it can connect two or more separate networks. Switch can send data packets to all connected computers in a single network because switch works at the data link layer of OSI model and it identifies MAC address of each computer connected in a network; but switch cannot send data packets from computer of one network to the computer of another network because switch cannot understand IP address; whereas router understands the IP address along with the host and network address. Therefore router can send data packets from computer of one network to the computer of another network by identifying the IP address of networking devices connected to it.
Network Repeater
Now let us learn about the network repeater;
Repeaters are network devices that operate at physical layer of the OSI model. Repeater amplifies or regenerates an incoming signal before retransmitting it to the next node. Repeaters are used in the networks to expand its coverage area. So the repeaters are also known as signal boosters.
Repeater can boost both types of signal; the signal which is directing through the cables as well as the signal of Wi-Fi devices. The Wi-Fi repeater forwards wireless signals from the router to cover a wide area; such as multiple floors in an office building.
Therefore the role of repeater is to regenerate the weak signal over the same network before the signal becomes too weak for extending the length to which the signal is required to be transmitted across the network.
Network Firewall
Now let us discuss about firewall; there are two types of firewall one is hardware firewall and the other is software firewall.
Software firewall is a program works on define set of security rules that is installed in the system which ensures security for that system by controlling outgoing and incoming network traffics.
Antivirus that is installed in our system can work as software firewall and windows operating system has its own software firewall application which gets installed in the system automatically when we load the window operating system.
Hardware firewall is a network hardware device that monitors and filters incoming and outgoing network traffic based on a defined set of security rules for all internal networking devices of an organization. Therefore it acts as a barrier between internal private networks of the organization and external public network of the internet.
Therefore the hardware firewall allows non-threatening traffic inside the internal private network and prevents malicious or unwanted data traffic of the external public network for protecting the computer of the organization from viruses and attacks.
DHCP Server
DHCP Server is a server having a database which holds private IP addresses between a defined range that automatically assigns those IP addresses, default gateways and other network parameters to other connected client machines. DHCP server follows the standard protocol known as Dynamic Host Configuration Protocol; so DHCP responds to broadcast queries by its client machines.
Therefore it is a network management protocol that is used to automate the process of configuring IP addresses to machines in a network; this allows our devices to use network services such as DNS and any communication protocol based on UDP or TCP.
Let us understand the same with an example.
In an organization we have five computers and those five computers are needed to be assigned with their IP address but that should not be static IP addresses. DHCP server will have number of IP addresses in its database pool and from that IP pool it will lease IP address to each system as per the sequences of request from client machine for a stipulated period of time and on expire of the lease period another IP address or the same IP address may be provided by the DHCP server.
DHCP server is not any particular device rather different devices like router, firewall and many other devices play the role of Dynamic Host Configuration Protocol; therefore many devices can be used as DHCP server for an organization.
DNS Server
DNS server is a server having a database which holds public IP addresses and their associated hostnames or domain dame. It translates those domain names to IP addresses as requested by the user systems and DNS servers run special software to communicate with each other using special protocols.
Now let us discus; how the DNS server works but before that we need to learn about DNS.
DNS or Domain Name System is a decentralized naming system for computers containing some resources and which is connected to the Internet or a private network. Each networking device has unique set of numbers which is known as IP address of that device and when any device wants to communicate with another device in a network then it is only possible to find that intended device by its unique set of numbers which is known as IP address.
But the problem is that it is not easy to remember the IP address of those devices which we want to request in order to access its resources. That is why the DNS plays the vital role to let us remember the short names instead of those complex numbers while we are going to fetch resources across the network.
It is enough easy to remember the short name as facebook.com instead of remembering 69. 176. 13. 69. So the DNS Domain Name System is the process of mapping a unique short name with a unique set of IP address for a particular device in a network.
Now let us talk about the DNS server; so the DNS Server store all public IP addresses along with its associated short names that is domain names or we can also say host names. When our system send request to any server over the network through its domain name; let say facebook.com then our request will first go to the DNS server then the DNS server will search the IP address of facebook.com from its database. Now after finding the IP address of that requested domain name then DNS server will send back the IP address to our system. Now our system comes to know the exact IP address of its associated domain name like 69. 176. 13. 69 for facebook.com. So now our system will find the intended server that is the facebook server by the unique IP address as 69. 176. 13. 69 over the internet.
If any system request for recourse from any server over the network through its IP address instead of domain name then the service of DNS server will not be used. Therefore the system can directly access another system over the network by searching through IP address. If the same request is processed by using domain name instead of IP address then the DNS server will play its role in between those two devices. That is why; when we access any server or any device that is connected in the private or public network through IP address then it responds quicker compare to; when we request through domain name as it takes some more seconds by the DNS server in between to search the intended device's IP address from its database and sending back to the calling device to re-access again with the IP address.
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