A hub is a simple, less intelligent, and inexpensive networking device that is used for sending frames/frames from one device to rest of devices that are connected to the hub.
In this article, we will discuss what is Hub in networking, its advantages and its limitations in detail. We will also discuss how hub in computer networks work.
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What is Hub in Computer Networks?
Hub is a networking device that operates on the physical layer i.e. the 1st layer of the OSI model, unlike switches that operate in data link layer. Hub connect multiple devices to itself that send and receive data through it. It is a multiport repeater that comes with add-on functionalities, such as indicating any issues with the device. They come in different variants such as 4, 8, and 16 port hubs.
Hub is a device that works as a central connection among all network equipment and handles a data type called frames. It is connected to multiple devices that allow forwarding. Any data coming from one of the connected devices in the hub can be forwarded to another connected device.
How Does a Hub Work?
A hub is a network device that consists of multiple ports. Each port can connect one device. Multiple devices get connected to the hub through these ports. A connected device, say 1, sends the frame (sender). This frame will be delivered to all the connected devices (receivers), say 2,3, and 4 in this case.
Suppose devices 1 and 2 simultaneously send frames/frames to the hub. Due to this, frames often crash. N number of collision domains are possible in the hub, where N refers to the number of devices connected to the hub. Whenever this collision occurs, the host that has sent the frame will detect it. The sent frames are destroyed, and the host sends a jam signal for other hosts to wait. The waiting period is different for each host to avoid any further collision.
Although the frame is sent to all ports, a connected device only accepts those frames or frames whose MAC matches the destination MAC address field. The rest of the frames are discarded by that device.
Types of Hubs in Computer Networks
Let us now discuss the three types of network hubs in computer networks.
1. Passive Hubs
There are no computerized elements in a passive hub, and they are used for connecting signals from different network cable segments. They are simply connectors that connect wires coming from different devices in star topology. There is no processing or regeneration of signals in these hubs and they can only repeat or copy the signals. Due to this, they do not require electricity. They also do not clean the message. Passive hubs neither amplify nor boost signals since the cable distance is reduced by half.
2. Active Hubs
Active hubs monitor, amplify and regenerate weak signals between nodes for which they require electricity. When a port sends a weak signal in a readable condition, the active hub reconstructs it to strengthen, and then it sends it to ports. These hubs check the data that is to be sent to decide which data is to be sent first. In case there are any damaged data packets, they can also fix them. They help in extending the distance between nodes, but they also amplify noises. Compared to passive hubs, these hubs in a computer network are expensive.
3. Intelligent Hubs
These hubs are smarter than passive and active hubs. They consist of Management Information Base (MIB) that specifies those conditions that can be monitored and those functions that can be managed. This software helps in analyzing and resolving any problem in the network. They work in a similar manner to active hubs, and they also have remote management capabilities. These hubs allow administrators to monitor the traffic that is passing through the hub and they also allow the configuration of each port in the hub.
Advantages of Hub in Computer Networks
- Message broadcast: A host in a hub sends messages to every other device in the connecting network.
- Cheaper devices: Among routers, hubs and switches; hubs are the least expensive since they are purely hardware.
- Easy installation: It can be easily installed thus it automatically creates a local area network (LAN). Any further addition in devices is possible later on as well.
- Easy removal of damaged device: Due to the different connecting wires, the hub remains perfectly functional even if one of the network segments stops working. Suppose that the wire of connected device 1 gets damaged, the hub will still be able to send messages to the remaining connected devices 2, 3 and 4.
Limitation of Hub in Computer Networks
- Not intelligent: Unlike switch or router, hub is a less intelligent device since it does not have any software.
- Hub is everything: Total damage to the hub will cause the entire network to fail, even if all ports are perfectly functional.
- No filtering: Hubs do not allow packet filtering. This means that any data that is being forwarded to one device will also be forwarded to all connected devices. It, however, does not forward the frame to the port of entry. Since the hub is purely hardware, it does not have a MAC address for locating the target device.
- No security: Since the hub broadcasts messages to every port, it is not possible to send any private frame. This allows other connected ports to access your data.
- Network Traffic is high: Hubs broadcast the frame/data to every connected device due to which the traffic is high.
- Does not use full duplex transmission mode: Hubs use the half-duplex method for transmission. In the half duplex mode, you can either send a frame or receive a frame at a time. It is not possible to send and receive frames simultaneously.
- Cannot connect to different network architectures: Hubs cannot connect with different network architectures such as token, ring, and ethernet.
Hope this article has been able to provide you with the details of what is hub, its types and how it works. Hub is a device that is less intelligent and yet quite useful. They, however, lack the intelligence that other advanced hardware devices have. They are now less in use and are being replaced by more intelligent devices such as switches and routers.
Is hub a router?
No, while both are networking devices the two operate at different layers. Hub operates at the physical layer which is the 1st layer of the OSI model and the router operates at the network layer which is layer 3.
What is the difference between a hub and switch?
Again, just like a router, both hub and switch are networking devices. While the hub works at the physical layer to transmit signals to ports; the switch routes the information and then sent it over a network.
Are hubs still used?
Hubs lack software, due to which they have limitations. They lack privacy and security. Due to these reasons, they are being replaced by network switches.
Do hubs have any advantages over switches?
Hubs are typically simpler and less expensive than switches, but their advantages are outweighed by their inefficiency in handling network traffic compared to switches.
How can I identify a hub in a network setup?
Hubs are often smaller, have multiple Ethernet ports, and lack configuration or management options compared to switches.