In an Ethernet network, every client, server and network device is wired to a hub or switch. However, what is the different between hub and switch?
In a word: intelligence. Answer this in short sentence: Hub versus Switch - Shared versus dedicated channels!
Technically hubs operate at the layer one (Physical Layer) of the OSI model. When a computer sends data on the network it sends it in packets. Each packet is labeled with a Source and Destination address, known as MAC address. Hub does not inspect traffic quality or verify packet integrity. Its job is very simple: When it receives a packet of data at one of its ports from a PC on the network, it transmits the packet to all of its ports and, thus, to all of the other PCs on the network. Every computer connected to the hub "sees" everything that every other computer on the hub sees. The total bandwidth is shared among the computers. This is a highly in-efficient use of your network bandwidth. However, there is no processing delay created by the hub because the hub, by definition, does no processing.
All network data a hub receives on one port will be immediately transmitted out all the other ports. If two or more PCs on the network try to send packets at the same time a collision is said to occur. As such each computer must take it's turn before sending data. This is called half-duplex.
Switches control the flow of network traffic based on the address information in each packet. It will actively look at the traffic it receives and based on the destination address it will direct that traffic only to the port needed. The switch listens to each port at the same time without any interference. A computer plugged directly into the switch will not receive unnecessary traffic and can transmit to the switch whenever it needs to, this leaves all the bandwidth available to each machine.
The switch accomplishes this by maintaining a table of each destination address and its port. This is how it can intelligently direct traffic. Technically, switches operate at layer two (Data Link Layer) of the OSI model.
In summary, hub and switch differ in the way that they pass on the network traffic that they receive. While a hub shares the total bandwidth among all users, a switch provides a dedicated line at full bandwidth between every two devices transmitting to each other. By delivering messages only to the connected device intended, a switch conserves network bandwidth and offers generally better performance than a hub.
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