Difference between Hub and Switch

Even though switches and hubs are both used to link the computers together in a network; a switch is known to be more expensive and the network that is built with switches is typically said to be a bit faster than one that is rather built with hubs. The reason for this is because once a hub gets its data at one of the computer ports on the network, it will then transmit the chunk of data to all of the ports, before distributing it to all of the other computers on that network. If more than one computer on a single network tries to send a packet of data at the same time it will cause a collision and an error will occur.

When there is an error in the network all of the computers will have to go through a procedure in order to resolve the problem. It is quite a procedure as the entire process will have to be prescribed by the CSMA/CD (Ethernet Carrier Sense Multiple Access with Collision Detection). Every single Ethernet Adapter there is has their own transmitter and receiver, and if the adapters weren't required to listen using their receivers for collisions, then they would have been able to send the information while they are receiving it. But because they can only do one at a time, not more than one chunk of data can be sent out at once, which can slow the whole process down.

Due to the fact that they operate at only a half duplex, meaning that the data may only flow one way at a time, the hub broadcasts the data from one computer to all the others. Therefore the most bandwidth is 100 MHz, which is bandwidth that is to be shared by all of the computers that are connected within the network. Then, as a result of this, when someone making use of a PC on the hub wants to download a big file or more than one file from another PC, the network will then become crowded. With a 10 MHz 10 Base-T type of network, the effect here is to slow down the network to a crawl.

If you want to connect two computers, you can do so directly in an Ethernet using a crossover cable. With one of these crossover cables you will not have a problem with collision. What it does is it hardwires the transmitter of the Ethernet on the one PC to the receiver on the other PC. Most of the 100 Base-TX Ethernet adapters are able to detect when looking out for certain collisions that it is not necessary by using a system called the auto-negotiation, and it will run in a complete duplex manner when it's needed.

What this ends in is a crossover cable that doesn't have any delays that would be caused by collisions, and the data can be directed in both ways at the same time. The maximum bandwidth allowed is 200 Mbps, meaning 100 mbps either way.