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Network devices: Repeaters, Hub, Switch, Bridge, Routers, Modem, Gateway

Network Devices

Network devices are the components that are used to interconnect multiple computing devices to form a network, In order to share files or resources like printers or fax machines and for communications.

Types of networking devices

  • Repeaters
  • Hub
  • Switch
  • Bridge
  • Routers
  • Modem
  • Gateway

Repeaters

What is a repeater?

In communication when signals move from one place to another place they become weak and after a particular time, they lost their values and become a straight line. To increase the strength of the signal and get back the original data before the signal loss, repeaters are used.

“Repeaters are used to regenerate the signals before the complete loss of signal up to a particular limit.”

Regeneration means to recreate the signals before they lost their value.

We can't regenerate a signal, which is completely lost. We can't get back the data (we don't know whether it is 0 or 1 because the signal becomes a straight line)

If there is some strength there, then we can regenerate the signal.

 Characteristics of Repeater

  • A repeater is a re-generator, not an amplifier.
  • Filtering is not possible in repeaters.
  • Repeaters are simple device, which works on the physical layer of the OSI model.
  • Repeaters can connect segments of the same type of LAN.
  • We can increase the length of LAN by using repeaters. We will put repeaters in between the two segments and increase the length of LAN.
  • When data are coming from two different paths then there is a possibility of collision. In repeaters collided data is forwarded to the next node as it is (corrupted data) and to detect the collision we use a term collision domain.
What is Collision Domain?

Collision Domain is a network area where we can detect the collided frames we can  identify that the collision occurs. So when we identify that due to collision data is lost, we can resend the data.

Hub
  • Hub works at the physical layer of the OSI model.
  • Hub transfers the data from one incoming port to all other ports.
  • Hub is broadcasting the data to all nodes. It will not check whether that data is required at any node or not. It will send message to all nodes (except the node from where the data is coming)
  • The node that requires that data will receive it and other nodes will discard it. Example: When A wants to send data to B. Then A sends the data to hub and hub broadcasts it to all other nodes through its other ports. It will send it to B, C, D ... all nodes hence B requires that data so it will get that data and all other nodes discard that data.
  • In this device, traffic is shared by all nodes
  • Hub is used to create a LAN of Star Network topology or Hierarchical Network Topology
  • Addressing is not possible in the hub. Hub sends data to all nodes so no addressing is required.
  • No data filtering: hubs are not deciding what data is required to send and what to not.

Types of Hub

Active hub:  Active hub regenerates the signal then forwards it to all other nodes through other ports. It works like a repeater. So It is also known as a multi-port repeater

In repeater, we have only two ports one incoming and one outgoing but the Active hub has many ports in it.

In the Active hub, we need a power supply to regenerate the signals.

Passive Hub: Passive hub transmit the data to other port as they are without any modification in the signal. It is only used to forward the data So power supply is not required.

Switch

  • A switch is similar to hub but is an intelligent device.
  • It can detect specific devices that are connected to it and keeps a record of the MAC address of those devices.
  • That means it does not broadcast the data to all connect devices like hub instead it first reads the mac address the of all the connected devices and forward the incoming data packet to the destination port only.

How it recognize the destination port?

So, to recognize the destination port it uses its intelligence and reads the mac address present in the data packet. It doesn’t read the whole message instead it only read the address present in it.

Bridge        

                            

  • A bridge is used to connect two LANs.
  • The bridge has one incoming port and one outgoing port.
  • The bridge will check the data before sending it to the other side of the bridge.
  • It will check the destination address whether that address exists on the other side or not. If the destination address exists on the other side then it will transfer the data to the other side. If the destination address is not on the other side of the bridge then it will not transmit the data on the other side and discard it.
  • Bridges are used to extend the network with maintaining signals and traffic means which data has to be sent to the other side or not, is also decided here.
  • Bridges are used to extend the length of a network.
  • Bridges worked on Data Link Layer of OSI Layer.
  • In bridges, data are in the form of frames.
  • Data Filtering is possible here.

Router

  • A router is a device that routes or passes internet connection to all connected devices to it.
  • A router is an intelligent network layer device which connects two or more network which may be near or very far.
  • It can works in LAN and WAN environments.
  • It forward packets to other routers in the network.
  • It uses routing protocol to route data across a network.
  • It is more expensive than switches and hubs.
  • Doesn’t allow broadcast from one network to another.
  • It is a layer 2 device.
  • Filter data traffic.

Modem

A modem is a device that brings the internet into our homes or business. i.e it acts as a mediator between a computer and the internet.

Function of modem

As we all know that the signal used by a computer is digital and the signal used by the internet is analog so if the computer wants to use an internet signal then it must be converted in digital form and modem will convert the incoming signal to its suitable format.

So as analog data comes in from the internet the modem demodulates the incoming analog signals into a digital signal.

Also, a modem modulates outgoing digital signals from computer into an analog signal as it goes out on the internet.

Gateway

A gateway is a connecting device used to connect remote networks with the host network. Generally, it acts as an entry or exit point. Mostly gateway operates at the application layer.

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