What is the difference between a hub and a switch

The difference between a switch and a hub.

From the perspective of OSI architecture, hubs belong to the first layer physical layer devices of OSI, while switches belong to the second layer of data link devices of OSI. This means that the hub only plays the role of synchronization, amplification and shaping for data transmission, and cannot effectively deal with short frames and fragments in data transmission, and cannot ensure the integrity and correctness of data transmission; The switch can not only synchronize, amplify and shape the data transmission, but also filter short frames and fragments.

From the perspective of working mode, the hub is a broadcast mode, that is to say, when a certain port of the hub is working, all other ports have a name to listen to the information, which is prone to broadcast storms. When the network is large, the network performance will be greatly affected, so how to avoid this phenomenon? The switch can play this role, when the switch is working, only the port that makes the request and the destination port respond to each other without affecting the other ports, then the switch can isolate the collision domain and effectively suppress the generation of broadcast storms.

From the perspective of bandwidth, no matter how many ports the hub has, all ports share a bandwidth, and only two ports can transmit data at the same time, and the other ports can only wait; At the same time, the hub can only work in half-duplex mode. For switches, each port has an exclusive bandwidth, when two ports work, it does not affect the work of other ports, and the switch can work in both half-duplex mode and full-duplex mode.

For example: are 100m and hubs and switches.

If one uses that, your transmission speed is 100m

But if 2 people are going down at the same time, then what the hub offers is that the speed of 2 people adds up to 100m

However, the switch is able to provide 100m speed for everyone.

When it is three people, it is three people speed 100m combined, but the switch can provide 100m for each person

Also, the hub publishes information to each port, while the switch only sends information to the corresponding port.

The front-end shared bandwidth and the latter exclusive bandwidth.

The difference between a hub and a switch is reflected in four aspects: working level, data transmission mode, bandwidth occupancy mode, and transmission mode.

1. Different levels of work.

Switches and hubs work at the same time at Layer 1 (physical layer) and Layer 2 (data link layer), while switches work at least at Layer 2, and more advanced switches can work at Layer 3 (network layer) and Layer 4 (transport layer).

2. Different data transmission methods.

The data transmission mode of the hub is broadcast mode, and the data transmission of the switch is purposeful, the data is only sent to the destination node, but the first time it is sent in the case that it cannot be found in its own MAC address table, and then because the switch has the MAC address learning function, it is no longer broadcast after the second time, and it is purposeful to send again. The advantage of this is that the data transmission efficiency is improved, there will be no broadcast storms, and there will be no listening by other nodes in terms of security.

3. The bandwidth is occupied in different ways.

In terms of bandwidth occupancy, all ports of the hub are the total bandwidth of the shared hub, and each port of the switch has its own bandwidth, so that the bandwidth of each port of the switch is actually much higher than the available bandwidth of the hub port, which determines that the transmission speed of the switch is much faster than that of the hub.

4. The transmission mode is different.

The hub can only be transmitted in half-duplex mode, because the hub shares the transmission medium, so that the hub can only transmit one task at a time on the upstream channel, either receiving or sending data.

How the switch works

It can provide an exclusive electrical signal path for any two network nodes connected to the switch. The most common type of switch is an Ethernet switch. The switch operates at the second layer of the OSI reference model, which is the data link layer.

The switch has a high-bandwidth back bus and an internal fabric that can transfer data between multiple port pairs at the same time. The transmission modes of the switch are full-duplex, half-duplex, full-duplex and half-duplex adaptive.

The OSI architecture is different: hubs belong to Layer 1 physical layer devices, while switches belong to OSI and belong to Layer 2 data link layer devices. Works differently:

The hub is in broadcast mode, and when a port of the hub is working, all other ports can listen to the information, which is prone to broadcast storms, and the network performance will be affected when the network is large. Switches can avoid this. <

1. The OSI architecture is differentHubs belong to Layer 1 physical layer devices, while switches belong to OSIs and belong to Layer 2 data link layer devices. That is, the hub only plays the role of synchronization, amplification and shaping for data transmission, and cannot effectively process short frames and fragments in data transmission, and cannot ensure the integrity and correctness of data transmission; The switch can not only synchronize, amplify and shape the data transmission, but also filter short frames and fragments.

2. Different ways of working:The hub is in broadcast mode, and when a port of the hub is working, all other ports can listen to the information, which is prone to broadcast storms, and the network performance will be affected when the network is large. The switch can avoid this phenomenon, when the switch is working, only the request port and the destination port respond to each other without affecting the other ports, so the switch can isolate the collision domain and effectively suppress the generation of broadcast storms.

3. Different bandwidths:All ports of the hub share a bandwidth, and only two ports can transmit data at the same time, and the other ports can only wait, and the hub can only work in half-duplex mode. For switches, each port has an exclusive bandwidth, when two ports work, it does not affect the operation of other ports, and the switch can work in half-duplex mode or full-duplex mode.

Difference: The replacement works at the data link layer, through the MAC address ** data; The hub works at the physical layer, in the form of data in the form of broadcasting. The hub adopts a bus-type topology internally, which must be one-way at the same time and can only be maintained in half-duplex mode; The channels between the two ports on the switch are independent of each other, allowing for full-duplex communication.

The hub works at the physical layer, which belongs to Layer 1 devices, and all ports can receive each data sent, using the way of broadcasting, so the network performance is greatly limited.

The switch works at the data link layer and belongs to Layer 2 devices, and each port forms a MAC address table based on the MAC address data of the packet, rather than in the broadcast form.