Hubs vs. Switches
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This page explains the difference between an Ethernet Hub and an Ethernet Switch which might at first glance seem to do the same thing. A hub is an ethernet (10BaseT or 100BaseT UTP/STP) repeater. If we take a typical 8-port hub, any data it receives on one port will be re-transmitted on all of the other seven ports. The intended destination could be on any of those ports. It's simple to understand but is not very efficient as there is no traffic control - if two PCs try to transmit at the same time, a 'collision' occurs and the data has to be re-transmitted. As such, even though your Ethernet card might be 'full duplex' it may be unable to actually transmit and receive simultaneously. Furthermore, a PC will have no interest in data which another PC is sending (for example) to a printer elsehwere on the network, so clogging up its ethernet interface is wasteful. Hubs are inexpensive and for small networks, the performance is often quite adequate. Hubs are available in both 10BaseT (10Mbits/sec) and 100BaseT (100Mbits/sec). Dual-speed hubs are also available, but will only allow segments of the same speed to talk to each other. A switch (sometimes called a 'Switching Hub') will look physically similar to a hub. A switch transmits data from one specific port to another, rather than re-broadcasting data to all other ports. A switch is intelligent and will learn which device is on which port, thus knows which port received data needs to be sent to. This makes the network much more effcient and allows more devices to communicate with each other simultaneously. Switches can be single speed (10 or 100BaseT) or dual speed. A good switch will allow segments of dissimilar speeds to communicate with each other (for example a PC running at 100BaseT can talk to a Printer at 10BaseT). |
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