It seems that switches can only be compared with hubs.

Because the principles of these two things are similar.

But there are also specific differences:

Switches and hubs cannot be distinguished simply by their ports, external shapes, and connection methods. They should be identified mainly from the following aspects.

Eight Notes

1. Pay attention to the appearance: The panel in front of the switch has three rows of lights, and the panel in front of the hub has two rows of lights to show related functions. When there is data exchange, LNK/ACT will flash. When the 10/100 light is on, it means it is working at a speed of 100M; when it is off, it means it is working at a speed of 10M. When the DOP/COL light is on, it means it is working in duplex mode, and if it is off it means it is working in simplex mode. The hub does not have this light because the hub can only work in simplex mode, so there is no need for this indicator light.

2. Pay attention to the working principle: the hub belongs to the first physical layer device of OSI, and the switch belongs to the second layer data link layer device of OSI. This means that the hub only plays a role in synchronizing and shaping data transmission, and cannot effectively process short frames, fragments, etc. in data transmission, and cannot guarantee the integrity and correctness of data transmission; switches can not only Data transmission can be synchronized, amplified and reshaped, and short frames, fragments, etc. can be filtered.

3. Pay attention to the port function: the switch divides the conflict domain but the hub does not divide the conflict domain. This is like a switch dividing each port into its own channel, and the data exchanged by all ports go their own way without affecting or conflicting with each other. However, the hub assigns all ports to the same channel, and the data of all ports must go through one channel. Everyone must negotiate. As the transmission volume increases, the number of conflicts increases. When any computer on the network sends and receives data, all other computers can receive it, and these computers cannot send and receive data at the same time, otherwise a collision will occur. This is why the backplane bandwidth of the 3616NS switch can reach 3.2G, so as to ensure that the channel of each port can reach 100M without bottleneck problems. Generally, the bandwidth of the backplane of a 100M hub is only 100M, which is why their transmission speeds vary greatly.

4. Pay attention to the working mode: the hub is a broadcast mode, which means that when a certain port of the hub is working, all other ports can listen to the information, which is prone to broadcast storms. When the network is large Network performance will be greatly affected. When the switch is working, only the port that sends the request and the destination port respond to each other without affecting other ports. Therefore, the switch can isolate the conflict domain and effectively suppress the occurrence of broadcast storms.

5. Pay attention to the bandwidth: No matter how many ports the hub has, all ports share one bandwidth. Only two ports can transmit data at the same time, and other ports can only wait; and for For switches, each port has an exclusive bandwidth. When two ports are working, it does not affect the work of other ports. Unlike a hub, where all connected users share the full available bandwidth, a switch provides dedicated bandwidth to each connected network device. For example, a 100 Mbps hub will provide 100 Mbps of shared bandwidth to all connected devices. However, switches of the same level can provide 100 Mbps of dedicated bandwidth for each connected device, and the performance will be greatly improved.

6. Pay attention to the type of network connection: Nowadays, switches can provide high-speed connection ports such as Ethernet and Fast Ethernet, while hubs can only connect to the same type of network.

7. Pay attention to the network speed: a hub can only transmit data through two ports at the same time, while a switch can transmit data between multiple port pairs at the same time. For example: When an 8-port 10/100M hub and switch are working at full load, the total traffic of the hub will not exceed 100M, while the total traffic of the switch can reach 800M. Switches and hubs are no longer of the same order of magnitude in terms of speed.

8. Pay attention to network stability: Unlike the hub that simply sends the received signal repeatedly through all ports, the switch can check each received data packet and process the data packet accordingly. . The physical addresses of all nodes on each network segment are stored in the switch, and only necessary network traffic is allowed to pass through the switch. Through the filtering and forwarding of switches, network broadcast storms can be effectively avoided, signal collisions in the network can be reduced, and packet errors and packet errors can be reduced.