Hub: shared bandwidth devices, multiple computers can simultaneously interface with a line composed of local area network or the Internet. .English called the "Hub". ."Hub" is the "center" means, the hub's main function is to regenerate the received signal shaping zoom in to expand the network's range, while all the nodes in order to focus on it as the center of the node. .It works on the OSI (Open Systems Interconnection Reference Model) reference model the first layer, namely, "physical layer." .Hub and network card, cable and other transmission media, as part of the LAN infrastructure, the use of CSMA / CD (a detection protocol) access method. .
hub Typical applications
network hub is a pure hardware .the bottom of the device, basically similar to the switch does not have "smart memory" capabilities and "learning" capability. .It does not have the switch has the MAC address table, it sends the data are not targeted, instead of using broadcasts. .That is when it sends data to a node, not directly send the data to the destination node, but to send packets to all nodes connected with the hub. .
hub (HUB) is the data communication system infrastructure, it, and twisted-pair transmission medium such as a software without any support or .minimal management software manages the hardware. .It is widely applied to various occasions. .Work in the local area network hub (LAN) environment, as the same card, used in the first layer of the OSI reference model, it is also known as the physical layer device. .Using the electrical interconnection within the hub, while maintaining the LAN environment is a logical bus or ring-type structure, can be used to create a physical hub, star or tree network structure. .In this regard, the role of the hub is equivalent to multi-port repeater. .In fact, the hub is actually a repeater, which differ only in the hub port to provide more services, so called multi-hub repeaters mouth. .
hubs work characteristics according to IEEE 802.3 .agreement, a hub function is randomly selected port facilities, and make it exclusive full bandwidth, and associated equipment on a hub (switch, router, or server, etc.) to communicate. .It can be seen, the hub at work with the following two characteristics. . first multi-port Hub is just a signal amplification devices, work when a port receives the data signal, the signal from the transmission source port to the Hub has been a process of .attenuation, so the Hub will be shaping the amplified signal, the signal to be attenuated regeneration (recovery) to send the state, immediately forwarded to all other ports in working condition. .From the Hub's work can be seen, it is only in the network play the role of signal amplification and retransmission, which aims to expand the network's transmission range, but not with the directional signal transmission capacity, is - a shared standard equipment. .Therefore called a hub for the "silly Hub" or "dumb Hub". . followed by the Hub and it's only on the associated equipment (such as the upper Hub, switch or server) to communicate with the layer between the port will not communicate directly, but through .information on the associated equipment and then broadcast to all ports. .Thus, even in the same Hub of communication between the different two ports, must go through two steps: The first step is to upload information to the associated equipment; second step is then the information on the associated equipment .broadcast to all ports. . hub installation
Hub of the basic working principle of
We know that the ring-type network, there is only one physical signal .transmission channels, through a transmission medium to transmit, so there is competition for the channel of the nodes in the conflict, the transmission efficiency is low. .Introduction of assembly line equipment hub of this network, each with its own station is a dedicated transmission medium connected to a hub, not only between nodes of a transmission channel, each node of the signal sent back through the hub .concentration, then the signal shaping hub, amplified and sent to all nodes, so that at least no longer appears on the uplink channel collision phenomenon. .However, hub-based network is still a shared media LAN, where the "sharing" is actually a hub within the bus, so when the uplink channel and downlink channel to send data signals will still exist when the collision phenomenon. .When the hub port from its internal collision is detected, a collision enhanced signal (Jam) is connected to the hub destination port for delivery. .Then send all the data will not be successful, a network of "big traffic jam." .
hub of the installation is relatively simple, especially .fool hub, as long as its fixed in the wiring closet and plug in the power cable. .Which need to connect twisted-pair, twisted-pair which put the head into the RJ-45 to the hub port. .Although he is intelligent hubs and fixed line can be used, however, if you want remote management, we must make the necessary configuration, specify the IP address information for the hub. .Also in some large networks generally use rack-mounted hub, thus related to the hub chassis installed. . .