I am newbie to network.
I have been learned What hub is in Microsoft MVN Network course
Can I say Hub is device which sends data to all connected nodes whenever it received data from a notice?
The reason I asked this question is that I don't know definitely what node is..
Yes.
Before hubs using 10-BASET or 100-BASET there were 10-BASE5 and 10-BASE2. They were a single cable connecting all the nodes (PCs, printers, etc.).
Imagine a single cable going through an office, if someone step on the cable or pull violently the cable, he could break it and turn down the whole network.
Imagine moving a PC to another site in the office. If there wasn't a connector in the cable in that place they had to cut open the cable and put a new connector, it means having the network down during that time.
To overcome these and other problems the industry moved from the linear design to a star design.
In the star desingn each node uses a cable (UTP) that connect to a single point (the hub). The hub has the mission to act as a repeater on all its ports to emulate the single cable functionality.
For each frame received on a port, all the others will repeat the frame so everybody is able to see the same data as if they were connected to a single cable.
A "hub" is an OSI layer 1 device.
This means whatever the network protocol is (for example, Ethernet), any packet received on any port, it duplicated and sent to all ports. This is usually called "bridging".
A "switch" is an OSI layer 2 device.
Although they can do many other things, their primary different from a "hub" is that the switch keeps track of what device addresses are on which of its ports. When a packet arrives on one port, if the switch knows where the receiver address is located, the switch forwards it to only that one port.
More about switches can be found in this question.
