In this article, we will discuss What is hub in networking? How its work? Basic features of the hub network. Why hub is a physical layer device? Types of Hub and Advantages and Disadvantages of a hub network.
Hub in Computer Network:
A hub is a networking device that is used to connect multiple devices or segments on a local network.
It is a physical layer (layer-1) device that simply broadcasts all incoming data to all other output ports. means if a hub has eight ports, then any input data that arrives on port 1 will be transmitted on ports 2 through 8.
It is not an intelligent device because it does not have any memory to store device information. If a computer wants to send information to another computer, the hub broadcasts information to all the other computers, connected to the hub, that’s why it is not an intelligent device.
How Hub Works?
Hub works like an electric wire, it receives data signals from one device in his one port and forwards to all the other ports, except the source port. It does not have any capability to identify any frames to know where it should forward because it does not maintain any kind of table like switch. So there is a lot of traffic on the network and network performance is also very poor, only one device transmits information at a particular time.
It works on star topology physically because all the devices are connected to the central node, but logically it acts as a bus topology.
Basic Features of Hub Network:
Always Broadcast: Hub always broadcasts the data, means whatever computer will connect with the hub, it will broadcast data to all those computers.
Half-duplex Communication: Hub can communicate only in the half-duplex method. Only one computer can transmit data at a particular time, if other computers want to transmit data, then it has to wait.
Other computers can not send data at the same time. If another computer sends data at the same time, the message will collide from both computers.
Single Collision Domain: Hub works on a single collision domain means Two PC’s cannot send data at the same time if they send data at the same time, the packets collide each other and the packet destroys.
Use only local network: Hub network is used only in the local network means you can use this network in your home or in a small department, etc. This hub network cannot be used in larger networks.
Cannot store MAC: It is not an intelligent device. It cannot store the MAC address of computers. It does not maintain any kind of table.
Why hub is a physical layer device?
Hub is used in a physical layer because it is not an intelligent device, it does not maintain any kind of table like a switch. It works like a cable (or connector), it’s just simple blindly forward data to all the connected devices like a cable. Two devices can not send data at the same time if they try, the packets will collide with each other.
Types of Hub in networking
- Active Hub
- Passive Hub
Active hub needs electricity (AC power) because, it regenerates signals, makes it powerful again, and then sends it forward so it can communicate for long-distance. It acts as a repeater and also known as “multi-port repeater”. It can extend communication distance over a network.
Passive hub is simply used to create a network, where it simply receives packets and broadcast it over the network. It does not amplify signals. It simply receives signals and forwards it.
Benefits or Advantages of Hub Network
- It can boost the signal which helps to extend the network.
- It is cheaper than other networking devices.
- It supports different types of network devices.
- We can easily create a small network using a hub device.
Drawbacks or Disadvantages of Hub Network
- There is no security in a hub network because message broadcast to all devices so anyone can access the message.
- It works on half-duplex mode means only one device can communicate at a time.
- It works on a single collision domain if two or more devices try to send data at the same time, the packet collides with each other.
- There is no data retransmission means if the message destroys during transmission for any reason, it will not transmit again.
- It cannot store the MAC address because it does not maintain any kind of table.
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