What does hub

Simply put: what is a hub?

We all work every day with networks that are interconnected in a wide variety of ways. Appropriate network devices are required so that the computers can exchange information with one another. The most rudimentary form of these are so-called hubs. Here you can find out how a hub works and why he one Switchtechnically inferior is.

What is the fundamental difference between a hub and a switch?

A hub always sends data packets to all ports, while a switch forwards them to one or more specific ports.

How secure are hubs?

Broadcasting the data packets theoretically always means that they can be intercepted by unauthorized third parties with very little effort.

Are hubs even used these days?

The hub is an outdated technology that is hardly relevant anymore. Therefore, in practice, they are used almost exclusively for streaming media content.


1. Definition: What is a hub and where is it used?

A hub (English for “hub” or “node”) is a network device that connects several hosts within an Ethernet. In network technology, it serves as a distributor for the data packets. Hubs work on layer 1 (physical layer) of the OSI model. Your Function is limited to distributing. They are therefore nothing more than a simple form of switches or routers.

The hub receives the data packet and then forwards it to all of its ports.

The hub receives a packet and then forwards it to all other ports, i.e. it sends a broadcast. In this way, all hosts receive the relevant data packets, even if they are not actually the recipient. This means that not only all ports but also all host systems are occupied at the same time. For the hosts, on the other hand, this means that they cannot send any data packets as long as the hub is running, since otherwise there would be collisions. If the device receives requests at the same time, it processes them one after the other.

All hosts connected to the hub share the available bandwidth (e.g. 100 Mbit / s). This leads to a loss of speed, especially when uploading large amounts of data. A hub is therefore a rather outdated technology and in practice is only suitable for streaming media content, since only one transmitter is supposed to transmit to all other devices anyway.

Good to know: If the number of connections on the hub is not sufficient for all hosts, you will need another hub. The two devices are connected with a crossover cable via one of the uplink ports. The number of hosts that can be connected is limited, however, as the 5-4-3 rule (also known as the repeater rule) applies in this case.

2. How is a hub different from a switch?

In contrast to a hub, a switch can not only send and receive data at the same time, but also forward the packets to various network devices using unicast or multicast. However, the traffic is only sent to the port to which the recipient in question is connected.

If two devices communicate with each other in the network, this has no effect on the sending and receiving speed of the other devices. While a hub limits the bandwidth, the switch always has the full bandwidth of the end-to-end connection available.

Ethernet switches work on layers 2 (data link layer) and 3 (network layer) of the OSI reference model, which means that they support every packet protocol. Thanks to the intelligent transmission of data packets, switches are also suitable for fast forwarding in large network architectures. However, due to the greater range of functions, switches are usually significantly more expensive than hubs.

Good to know: LANs ("Local Area Networks"), in which switches are used to connect individual segments, are also known as "Switched LANs" or "Switched Ethernet LANs".

3. Hub vs Switch: How it works in detail

Both hubs and switches serve as the central coupling element for your network devices and process a certain type of data, the so-called frames. These are responsible for the data transport. If the device receives a frame, it is amplified and then forwarded to the port of the destination host.

The fundamental difference between a hub and a switch lies in the way in which the frames are delivered.

In contrast to the hub, a network switch is able to differentiate to which recipient the data packet is to be delivered.

As already mentioned, a hub transfers the frames to each of its ports, even if these are only intended for a single connection. This ensures that they always achieve the intended goal. The hub therefore has no way of differentiating exactly to which port the data packet is to be sent.

It is precisely this fact that ultimately leads to the aforementioned loss of speed and slow response times, since the network (in addition to the shared bandwidth) is also loaded with an unnecessarily high volume of traffic. In addition, the principle naturally also creates significant security gaps.

A simple example to explain:Peter wants to invite his colleague Anne to dinner and sends an email, which is first forwarded to the hub. He sends a request to all hosts, including Tina from accounting, who has been keeping an eye on Peter for a long time. Tina's computer rejects the request, Anne's computer accepts it. With appropriate IT skills, Tina would still have the opportunity to intercept the message and appear in Anne's place for the date with Peter.

3.1. The switch is also basically a hub - but much smarter

In contrast to this, a switch records the MAC addresses of all devices connected to it. Thanks to this information, he can recognize which host belongs to which port. If it receives a frame, it knows exactly to which connection it has to pass it on. In this way, in principle, each port creates its own collision domain.

In our example, the switch would forward Peter's message directly to Anne's computer. This automatically leads to a higher level of data security, because Tina's computer is not sent any queries.

Good to know: Routers offer a much larger range of functions than hubs or switches, including, for example, DHCP or NAT. They also allow communication between different networks.

You can also find an overview of the various network devices in the following YouTube video:

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Simply put: what is a hub?
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