About the changing technology in the networking field.
To understand the differences between a Hub and a Switch is to understand the functionality of each in turn. Once the functionality of each is understood it will be easier to understand the differences between the two and be able to select one or the other based on your own business or network requirements.
A hub is a Layer 1 OSI Model network device that provides central connectivity for a number of devices such as computers and printers, which are connected to the hub using twisted pair cabling. The function of a hub is to act like a multi-port repeater: perform signal amplification which decreases the chances of data within the data packet from being distorted or corrupt before reaching its destination. A Switch works at the Layer 2 of the OSI mode and just like a hub they provide central connectivity for all devices, using twisted pair cabling. Both the hub and the switch are single points of failure: if either one fails, the whole network fails. And this is where the similarity ends!
The most important function of network devices such as a hub or switch is to ensure that the data packets reach their intended destinations, but how these packets are handled between the two devices is vastly different. When a hub receives a data packet, it amplifies the signal and broadcasts it out through all ports. A switch is far more effective and intelligent at handling data packets than a hub because it contains a MAC address table. This table contains a series of destination addresses, each of which is assigned to a port belonging to the respective printer, workstation, or other device connected to the port. When a switch receives a data packet, it performs a lookup routine where the destination address of the packet is compared to those stored in the MAC address table. If there is a match, the switch “switches” the packet from the incoming port to the appropriate destination port and sends the packet out. A switch does not broadcast the packets out onto the network like a hub; therefore, when a hub is used, the network or network segment is referred to as a Broadcast Domain. When a hub is used, the chances of data packet collisions are high because a hub might broadcast a packet at the same time as one or more workstations. The collision and subsequent actions are handled by the Carrier Sense Multiple Access with Collision Detection. A switched network contains no such broadcast or collision domains except for each connection between the workstation and the switch. Using a switch in a network therefore greatly improves network performance and efficiency as there are no delays and the amount of traffic is reduced due to no broadcasts.
Hubs are best used in small networks, of around 30 or fewer workstations, where traffic requirements are relatively low; switches are used where there are 10s more workstations to be connected and networks that have high traffic requirements.
When hubs are used in big networks with lots of data packets flying around, data packet collisions will occur frequently therefore reducing network performance. If switches are used, the data packets will be dealt with more effectively through the switching process described earlier, therefore increasing network performance. Switches can also be daisy-chained (linked together) in very large networks; not possible at all with hubs.
Another major difference between the two that determines the performance of a network is that hubs operate in half duplex mode, and switches operate in full duplex mode. In basic terms, this means that the hub can only receive or transmit data packets at any one time; it cannot perform both functions or else, as mentioned earlier, collisions will occur. Switches can both send and receive data packets simultaneously.
To conclude, as always whether you choose a switch or a hub depends on your network and business requirements. Switches may cost more than a hub, but a switch can also perform signal amplification as well as a host of other features and options that does not exist with a hub. Even if your network is small at this time, a switch might still be a wise investment as the network would be scalable and future proof.
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