The working principle of the hub is that the hub works in the physical layer of the OSI/RM reference model and the MAC (Media Access Control) sublayer of the data link layer. First, the node sends a signal to the line and the hub receives the signal. Because the signal is attenuated in cable transmission, the hub shapes and amplifies the attenuated signal after receiving it, and finally the hub broadcasts and forwards the amplified signal to all other ports.

Hub belongs to the bottom equipment of pure hardware network, and basically does not have the "intelligent memory" ability and "learning" ability of switches, nor does it have the MAC address table that switches have. When it sends data, it is not targeted, but broadcast. When it wants to send data to a node, it does not send data directly to the destination node, but sends data packets to all nodes connected to the hub.

Extended data:

From the perspective of LAN, hubs can be divided into five different types.

1, single relay network hub

The simplest hub is a kind of hub used in the simplest trunked LAN network segment, similar to stacked Ethernet hub or token ring multi-station access unit (MAU).

2. Multi-segment hub

It comes directly from the single-relay-segment hub, adopts the backplane of the hub and has multiple relay segments. Its main advantage is that users can be distributed on multiple relay network segments to reduce the information traffic load of each network segment, and the information traffic between network segments generally needs independent bridges or routers.

3. Port switching hub

Based on multi-segment hub, the integrator automates the connection process between user ports and multiple backplane segments, and realizes it by adding port switching matrix (PSM). PSM can provide an automatic tool for connecting any external user port to any trunk network segment on the hub backplane.

4. Network Interconnection Hub

Port switching hubs focus on port switching, while network interconnection hubs can provide some kind of integrated connection between multiple network segments on the backplane, which is completed by integrated bridges, routers or lan switches. This kind of hub usually takes the form of chassis.

5. Switched hub

The boundary between hubs and switches has blurred. The switching hub has a core switching backplane, and a pure switching system is used to replace the traditional * * * media sharing relay network segment. This kind of products have been put on the market, and hybrid (trunk/switch) hubs are likely to control this market in the next few years.

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