What signal does the hub receive, and how does the hub work?

The hub works on the following principle: the hub works at the physical layer of the OSI RM reference model and the MAC (Media Access Control) sublayer of the data link layer. First of all, the node sends a signal to the line, and the hub receives the signal, because the signal is attenuated in the cable transmission, the hub will shape and amplify the attenuated signal after receiving the signal, and finally the hub will broadcast the amplified signal to all other ports.

A hub is a hardware-only network underlying, and basically does not have a switch"Intelligent memory"Ability and"Learn"capabilities, and does not have the MAC address table that the switch has. It sends data without a specific purpose, and is sent by broadcasting. When it wants to send data to a node, it does not send the data directly to the destination throttle bridge point, but sends the packet to all nodes connected to the hub.

A hub is a device that connects multiple Ethernet twisted pairs or fiber bundles under the same physical medium. The hub is the physical layer that operates in the OSI model. It can be thought of as a multi-port repeater, and if it detects a collision, it will send a blocking signal.

Hubs often come with a BNCAND Oraui adapter to connect to a legacy 10Base2 or 10Base5 network.

Because the hub will regenerate or amplify any digital signal it receives, and then submit it from all ports of the hub, this will cause a high chance of collision between signals, and the signal may also be eavesdropped, and this means that all the Qiaoyanze devices connected to the hub belong to the same collision domain name and broadcast domain name, so most of the hubs have been replaced by switches.

Hubs are mainly used for the formation of shared networks, and are the most economical solution to solve the problem of going directly from the server to the desktop.

In a switched network, the hub is directly connected to the switch and sends data from the switch port to the desktop. The hub is flexible in networking, it is located at a star node of the network, and the workstations connected to the nodes are centrally managed, so that the workstations with problems do not affect the normal operation of the entire network, and users are also free to join and exit.

Hubs work in a local area network (LAN) environment, like a network card, and are applied to the first layer of the OSI reference model, so they are also called physical layer devices. The hub uses electrical interconnection inside, and when the environment in which the LAN is maintained is a logic bus or ring structure, it is completely possible to use the hub to establish a physical star or tree network structure.

Features of the work of the hub

First of all, the hub is only a multi-port signal amplification device, when a port receives a data signal, because the signal has been attenuated in the transmission process from the source port to the hub, the hub will shape and amplify the signal, so that the attenuated signal is regenerated (restored) to the state when it was sent, and then ** to all other ports in the working state.

The second is that the hub only communicates with its uplink devices (such as upper-layer hubs, switches, or servers), and does not communicate directly with each other on the same layer, but broadcasts information to all ports through the uplink devices.

However, with the development of technology and changes in needs, many of the current hubs have been broadened in terms of functionality and are no longer affected by this working mechanism. The network of hubs is shared, and hubs can only work in half-duplex.

1. Unmanaged hubs.

The simplest hubs provide ** network connectivity via an Ethernet bus, connected in the form of stars. This is called an unmanaged hub and is only used in very small networks of up to 12 nodes. Unmanaged hubs do not have management software or protocols to provide network management capabilities, and such hubs can be passive or active, with active hubs being used more.

2. Stacked hubs.

Stacked hubs are slightly more complex hubs. The most striking feature of a stacked hub is that the 8 ** devices can be connected directly to each other. This allows you to scale your network by simply adding a hub and connecting it to an already installed hub, which is not only inexpensive but also simple.

3. Chassis hub.

A chassis hub is a modular device that can be plugged into several types of modules on its backplane circuit board. Some hubs come with redundant backplanes and power supplies. At the same time, some modules allow users to replace failed modules without having to shut down the entire hub.

A hub is essentially a multi-port repeater. Within a local area network, the hub is the backbone and is used to optimize network cabling.

Structure, simplified network management and design. A network connected with a hub has a star-shaped topology, but still broadcasts internally.

, so it is still a bus-type network and should comply with the bus-type Ethernet networking rules.

The hub has functions such as signal regeneration, retiming, and collision detection: when the data signal reaches the hub, the data is collected.

The liner first implicitly compensates for the amplitude and phase distortion of this signal, and then regenerates the signal to something else connected to the hub.

The site broadcasts, so the NICs of all machines in the same network segment under the shared hub can receive the data.

Figure 214 shows that an attenuated signal is received from one port and then amplified before being broadcast to the other seven terminals.

The situation of the mouth. When multiple sites are transmitting at the same time, the hub generates a collision reinforcement signal based on the detected conflict, which is concurrent.

All sites connected to the hub.