Hardware Reference
In-Depth Information
Because switches establish a direct connection between the originating and receiving PC,
they also provide the full bandwidth of the network to each port. Hubs, by contrast, must
subdivide the network's bandwidth by the number of active connections on the network,
meaning that bandwidth rises and falls depending on network activity.
For example, assume you have a four-station network workgroup using 10/100 NICs and
a Fast Ethernet hub. The total bandwidth of the network is 100Mbps. However, if two
stations are active, the effective bandwidth available to each station drops to 50Mbps
(100Mbps divided by 2). If all four stations are active, the effective bandwidth drops to
just25Mbps(100Mbpsdividedby4)!Addmoreactiveusers,andtheeffectivebandwidth
continues to drop.
If you replace the hub with a switch, the effective bandwidth for each station remains at
the full 100Mbps because the switch doesn't broadcast data to all stations.
Most switches also support
full-duplex
(simultaneous transmit and receive), enabling the
actual bandwidth tobedoublethenominal 100Mbpsrating, or200Mbps.
Table 17.8
sum-
marizes the differences between the two devices.
Table 17.8 Ethernet Hub and Switch Comparison
