By PURPLELEC | 19 January 2024 | 0 Comments
What is the principle of USB-C hub?
The main function of the hub is to regenerate, shape and amplify the received signal to expand the transmission distance of the network, while concentrating all nodes on the node centered on it. It works on the first layer of the OSI (Open Systems Interconnection Reference Model) reference model, which is the "physical layer". The hub, like network cards, network cables and other transmission media, is a basic device in the local area network and uses CSMA/CD (a detection protocol) access method. Hubs are pure hardware network underlying devices and basically do not have the "intelligent memory" and "learning" capabilities similar to switches. It also does not have the MAC address table that the switch has, so when it sends data, it is not targeted, but uses broadcast mode to send it. That is to say, when it wants to send data to a certain node, it does not send the data directly to the destination node, but sends the data packet to all nodes connected to the hub, as shown in the figure.
This method of broadcasting data has the following shortcomings:
(1) User data packets are sent to all nodes, which is likely to cause insecurity in data communication. Some people with ulterior motives can easily intercept other people's data packets illegally;
(2) Since all data packets are sent to all nodes at the same time, coupled with the shared bandwidth method introduced above, it is more likely to cause network traffic jams and further reduce network execution efficiency.
(3) Non-duplex transmission, low network communication efficiency. Each port of the hub can only carry out data communication in one direction at the same time, and cannot perform bidirectional duplex transmission like a switch. The network execution efficiency is low and cannot meet the communication needs of larger networks.
Although hub technology is constantly improving, it essentially adds some switch (SWITCH) technology and has developed to today's stacked hubs with stacking technology. Some usb hubs also have smart switch functions. It can be said that hub products have made a technical transition to switch technology and have certain intelligence and data exchange capabilities. However, as the price of switches continues to drop, the only price advantage is no longer obvious, and the market for hubs is getting smaller and smaller, and is on the verge of elimination. Despite this, hubs are still economically attractive for families or small businesses, and are especially suitable for use in a home network with several machines or as a branch network for small and medium-sized companies.
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