Though the hottest new brand of telecommunications, Voice over Internet Protocol (VoIP) is packetized and transmitted as data bits, it is still characteristically similar to a traditional phone call most notably in that communication is two-way and both parties must transmit and receive data simultaneously. In a networking terms, this is considered Full Duplex communications and is a requirement to run VoIP over any network. There are several reasons for buying a Fast Ethernet Switch verses an Ethernet Hub for VoIP.
1. Controlled Ethernet Traffic
In a hub, a frame is passed along or "broadcast" to every one of its ports. It doesn't matter that the frame is only destined for one port. The hub has no way of distinguishing which port a frame should be sent to. Passing it along to every port ensures that it will reach its intended destination. This places a lot of traffic on the network and can lead to poor network response times.
A switch, on the other hand, keeps a record of the MAC addresses of all the devices connected to it. With this information, a switch can identify which system is sitting on which port. So when a frame is received, it knows exactly which port to send it to, which significantly increases network response times.
2. Bandwidth Utilization
A 10/100Mbps hub must share its bandwidth with each and every one of its ports. So when only one PC is broadcasting, it will have access to the maximum available bandwidth. If, however, multiple PCs are broadcasting, then that bandwidth will need to be divided between all of those systems, which will degrade performance.
A 10/100Mbps switch will allocate a full 10/100Mbps to each of its ports. So regardless of the number of PCs transmitting, users will always have access to the maximum amount of bandwidth. It's for these reasons why a switch is considered to be a much better choice then a hub.
3. Manageability
Hubs are considered "dumb" devices. They are strictly plug and play and are utilized to piece together an Ethernet network for simple IP communications. Hubs cannot be managed as Switches can. Switches have the option of unmanaged or managed, Layer 2 or 3. Todays switches can also act as routers and are called layer 3 switches with most of the functions you find in routers. Each individual port can be configured for a specialized network such as one for VoIP.
