Network Devices in Computer Networks

"Network devices" are devices that are used to create computer networks or to connect to computer networks. This post was created and published to provide a brief description of the most commonly used network devices.

There are numerous devices that contribute to the smooth operation of networks. Here is a list of some of those devices that are critical to network operation:

Modem

A modem is a type of computer peripheral that, in its most basic form, enables a computer to connect to and communicate with other computers by means of telephone lines.

You are able to combine the power of your computer with the reach of the telephone system all over the world through the use of modems.

You are aware that traditional telephone lines are unable to transmit digital information. Your computer's digital data are converted into analogue data by a modem, which is a format that is compatible with being transmitted over telephone lines.

In a manner very similar, the modem that is on the receiving end of the call will convert the analogue signal into digital data that the computer will be able to process. The process of converting digital data to analogue data and back again is called modulation and demodulation, and it is this process that gives the modem its name. It is this process that enables two computers to communicate with one another.

The process of sending data on a wave is referred to as modulation. As can be seen in the following list, the most common types of modulation techniques are as follows:

  • AM
  • FM
  • PM

AM denotes amplitude modulation, FM denotes frequency modulation, and PM denotes phase modulation.

You can send faxes to offices or important customers without leaving your computer if you have a modem and a standard telephone line.

You can also share recipes with other foodies if you have an online or internet connection. You can read the latest news, look at a weather map, and communicate with friends who live far away simply by using email and the internet, among other things.

Working of Modem

A modem is capable of converting the tones that are transmitted over a telephone line back into digital information, as well as converting a digital signal to the A/F (audio frequency) tones that are in the frequency range that can be transmitted over a telephone line.

The terminal will perform a self-check and assert the Data Terminal Ready (DTR) signal to notify the modem that it is ready when both the Data Terminal Equipment (DTE) and the Data Communication Equipment (DCE) are powered on.

The modem will send a signal to the terminal indicating that it is "Data Set Ready" (DSR) once it has been powered on and is prepared to send the data.

The modem connects to the computer on the other end of the line when it is controlled manually or by a terminal. If the computer is operational, it will respond with the tone that you have programmed into it.

Now, whenever the terminal is ready to send a character, it will let the modem know via the Request to Send (RTS) signal that it is doing so.

After that, the modem will send a signal to the terminal known as the Carrier Detect (CD) signal to let it know that it has successfully made contact with the computer. Clear-to-Send (CTS) is the signal that the modem sends back to the terminal when it is completely prepared to send the data over the wire. After that, the serial data characters are transmitted to the modem by the terminal.

When all of the characters have been sent by the terminal, the RTS signal must be brought to its highest level. Because of this, the MODEM will eventually stop transmitting and will lose its CTS signal. On the other side of the modem, computers and modems engage in handshakes that are nearly identical.

Types of Modem

Modems are classified into two types:

  • Internal Modems: These are modems that are built into the computer.
  • External Modems are modems that are connected to a computer in the same manner as other peripherals.

RJ-45

RJ-45 stands for "Registered Jack-45." Connecting computers on local area networks (LANs), and Ethernets in particular, typically requires the use of an eight-wire connector like this one.

In its most basic form, Ethernet is a local area network architecture that was developed by Xerox Corporation in collaboration with DEC and Intel. Ethernet can support data transfer rates of up to 10 megabits per second (Mbps) and can utilize either a bus or star topology.

The RJ-45 connector is physically very similar to the RJ-11 connector, which is the standard telephone connector. However, the RJ-45 connector is wider than the RJ-11 connector because it can accommodate eight wires rather than four.

In Ethernet local area networks, the RJ-45 connectors are what are used to connect individual computers to one another.

Ethernet Card

Ethernet, as you may know, is a LAN architecture developed by Xerox Corp. in collaboration with DEC and Intel.

Ethernet operates on a bus or star topology and can support data transfer rates of up to ten megabits per second.

Ethernet computers must have a special card called an Ethernet card installed.

An Ethernet card has coaxial, twisted pair, or both cable connections.

The connection will be BNC if the Ethernet card is designed for coaxial cable, and an AUI connector if it is designed for twisted pair cable. This can be used to connect an Ethernet card to a coaxial, twisted pair, or fibre optic cable.

BNC and AUI connectors are defined as follows:

  • The BNC connector, also known as the Bayonet-Neill-Concelman connector, is a type of standard connector that is utilized for the purpose of connecting 10Base2 coaxial cable (the Ethernet specification for thin coaxial cable).
  • The AUI (Attachment Unit Interface) connector is a 15-pin connector that can be found on Ethernet cards. This connector can be used to attach twisted pair cable, fibre optic cable, or coaxial cable.

When using this connection, there is always an external transceiver attached to the workstation in order for it to function properly.

Ethernet cards are typically acquired in a separate transaction from a computer; however, many computers, including the Macintosh, now come with the possibility of having an Ethernet card already pre-installed.

Hub

Simply put, a hub is a piece of hardware that allows multiple computers to be connected to one another and share resources.

You could also say that a hub is a centralized device that all other devices, like computers and printers, are connected to through in order to communicate with one another. As a consequence of this, a star topology was produced.

Concentrator is another term that's very similar. It is a piece of hardware that offers a centralized connection point for cables coming from workstations, servers, and other peripherals in the network.

In a star topology, the connection between each workstation and the central concentrator is made using twisted-pair wire.

In most cases, a hub will have the capacity to support 8, 12, or 24 RJ-45 ports. It is necessary to use specialized software in order to manage the ports, as these are typically implemented in a star or star-wired ring topology.

Types of Hub

Hubs may take on either a passive or active role in the network. As a result, there are only two primary categories of hubs:

  • Active hubs are distinguished from passive hubs by the fact that active hubs are capable of electrically amplifying the signal as it travels from one connected device to another. When the length of a network needs to be extended, active concentrators can be used in place of repeaters.
  • Passive hubs: The signal can travel from one computer to another without being altered when using a passive hub, which allows the signal to pass through.

How does the hub function?

Hubs are simple devices that connect user groups.

Hubs forward any data packets received over one port from one workstation, including email, word processing documents, spreadsheets, print requests, and graphics, to all of their remaining ports. All users connected to a single hub or a stack of connected hubs are in the same segment and share the bandwidth or data-carrying capacity of the hub.

As more users join a segment, they compete for a limited amount of bandwidth reserved for that segment.

Switch

Simply put, a switch is a device that is used to partition larger networks into smaller ones, which are then referred to as "subnets" or "LAN segments."

It is possible to prevent a network from becoming overloaded with traffic by dividing it up into several smaller subnets.

You could also say that a switch is a networking device because it connects other computers, networking devices, and different segments of the network together. Switches are sometimes referred to as multi-port bridges. The operation of the switch and the bridge are somewhat analogous to one another in some respects.

The task of filtering, which involves modifying the data in a specific manner, and the task of sending packets (a piece of a message that is being sent) from one LAN segment to another are both handled by a switch.

We refer to local area networks (LANs) that are segmented using switches as "switched LANs." Switched Ethernet LANs are the name given to local area networks that use Ethernet cables.

Operation of a switch

The operation of a switch differs from that of a hub in that when a hub receives data on its port, it sends the message to all connected devices, who then receive the message. And someone keeps the message for the recipient, while another discards it. Then there is some congestion.

In the case of a switch, the switch only transmits the data that is required. In other words, switch sent the message to the person in charge of that specific message, rather than to everyone.

Each of a network switch's ports has its own collision domain.

Our bridges had two ports that divided the network into two collision domains because this is a modified bridge.

Because we have a large number of ports here, each switch's port functions as a separate collision domain (a group of network interface cards where collisions can occur at any time).

For example, suppose we have four computers connected to each other in our network, namely computers A, B, C, and D. Assume that data is transferred from computer A to computer B in all four computers, and that data is also transferred from computer B to computer A. The communication is limited to computers A and B. When computers C and D want to communicate, they can do so as well. Both communications are independent and do not interfere with one another.

Layer 2 of the OSI model is where switching takes place. Layer 3 switches, also known as multi-layer switches, operate on layer 3, or the transport layer. Multilayer switching is also possible on layers 2, 3, and 4. As a result, it can also be used for routing.

However, if we only consider switches, they are devices that operate on the data link layer, or layer 2 of the OSI model. And if a layer 3 or multi-layer switch is added, it represents a layer 3 or multi-layer switch.

The switch receives its message in the form of frames on its port and transmits it to the device that receives the message.

Switches are an essential part of any LAN network. A LAN without a network switch is unthinkable. We can see that there are a large number of switches that connect with each other in the case of mid-to-large-sized LANs.

Switches can also be found in small or home offices.

Switches are a necessary component of today's LAN, and we couldn't imagine it without them.

The Benefits of Switch

We can exchange data at high speeds thanks to the switch. In other words, a switch operates on a 1000-bit or gigabit switch. They send data in gigabytes.

The switch allows for full-duplex communication. In an earlier example, we saw that system A communicates directly with system B while system C communicates directly with system D.

Latency is also very low here. Switches are extremely quick devices.

Our network's switches enable dedicated communication between devices. Switches also provide point-to-point data communication because data from one sender is routed directly to one receiver.

Repeater

A repeater is essentially a piece of equipment that acts as an amplifier for a signal that is being sent over a network.

A repeater is a device in a network that is used to regenerate, replicate, and amplify the signal that is coming in, and then sends that signal, which has been regenerated, replicated, and amplified, on to the next location in the network.

A repeater is utilized when the maximum rated distance for a single network run is exceeded by the length of the network line.

Both digital and analogue signals can be regenerated or amplified with the use of a repeater.

A distinction can be made between regeneration and amplification in this regard. If there is an impurity in the signal that is coming in, then that signal can also be amplified when it goes through the process of amplification. And in the process of regeneration, if there is an impurity in the incoming signal, then there is an extraction of the impurity from the incoming signal, which is followed by the signal being amplified or reconstructed so that it can be sent forward.

Repeater is an OSI model component that operates on layer 1. If we apply the OSI model to them, we will find that they operate on the physical layer.

That the data is received by the repeater in the form of 0s and 1s, and that it then amplifies the data as if it were data to be sent forward.

The signal that is sent along the cables that connect a network suffers degradation as the distance increases.

If there is an unacceptable amount of signal degradation, the message will not be delivered. Or, even if it does arrive, the message will have been corrupted to the point where it is useless.

Repeaters may be set up at various points along the path in order to guarantee that the data packets arrive at their intended location.

Types of Repeater

Repeaters are classified into two types:

  • Digital Repeaters amplify incoming signals, remove impurities, and then reconstruct the signal before sending it forward. Digital repeaters send the signal in its original quality.
  • Analog Repeaters amplify signals only.

Bridge

A bridge is essentially a device that connects two networks. A bridge is also a network device used to connect multiple network segments or multiple LAN segments.

Bridges are intelligent enough to recognize which computers are on which side of the bridge, and they only allow messages that need to get to the other side to cross. This improves the bridge's performance on both sides.

When a packet arrives at the bridge, the bridge examines the packet's physical destination address. The bridge then decides whether to allow the packet to cross.

Bridges are capable of filtering data traffic. MAC addresses are used in network bridge filtering.

Bridges operate in the data link layer, also known as layer 2 of the OSI model.

Router

A router is a device that functions similarly to a bridge but can handle multiple protocols. A router, for example, can connect Ethernet to a mainframe.

A router is also a specialized computer that can connect two or more computers. As a result, a router is referred to as a "internetworking device." A network that connects two or more networks is known as internetworking. To put it another way, internetworking is a network of networks.

Internetworking or creating a network of networks can be accomplished with the assistance of a router.

As I previously stated, a router is a computer, but it is specifically designed for routing purposes only. We can also use our computer as a router, which is known as a software router. However, when we compare a software router (our computer) to a hardware router (a router), our computer's software router performs too slowly in comparison to a hardware router that is specifically designed for routing.

The router contains an operating system and software, and data is transferred from one network to another using this router.

It creates a routing table for its assistance, which is known as the routing table. The router sends data from one network to another using a routing table.

If a router does not know the destination, it sends the traffic (bound for an unknown destination) to another router (via logical addresses) that does.

A router is distinct from a bridge in that the former employs logical addresses while the latter employs physical addresses.

A router can be used to control broadcast traffic as well.

How does a router function?

The primary function of a router is to connect networks. Routers are even smarter than hubs and switches.

Routers use the more complete address of a packet to determine which router or workstation it should go to next.

Routers can help ensure that packets take the most efficient paths to their destinations by using a network road map known as a routing table.

If the link between the two routers fails, the sending router can choose an alternate route to keep traffic flowing.

Routers operate at the network layer, or OSI layer 3.

Gateway

Simply put, a "gateway" is a piece of hardware that facilitates the connection of two distinct networks.

Gateways are devices that perform data translation and protocol conversion in order to enhance the functionality of routers.

In order to convert Ethernet traffic coming from a local area network (LAN) into SNA (Systems Network Architecture) traffic on an older system, a gateway is required. After that, it directs the traffic coming from the SNA to the mainframe. When the mainframe finally responds, the process will then go in the opposite direction.

In computer networking terminology, a "gateway" refers to a node on one network that acts as an access point to another network.

When it comes to businesses, the "gateway" refers to the computer that is in charge of directing traffic from workstations to the external network that is responsible for serving web pages.

The gateway is also associated with a router, which makes use of headers and forwarding tables to determine where the packets are sent, and a switch, which provides the actual path for the packet to travel in and out of the gateway. Both of these components determine where the packets are sent when they pass through the gateway.

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