Intel Ether express PRO/100+ TX PCI model B Installation Manual page 34

Shared hubs
In a shared network environment, computers are connected to hubs called
repeaters. All ports of the repeater hub share a fixed amount of bandwidth,
or data capacity. On a 100 Mbps shared hub, all nodes on the hub must
share the 100 Mbps of bandwidth. As stations are added to the hub, the
effective band-width available to any individual station gets smaller. Shared
hubs do not support full duplex.
Think of a shared repeater hub as a single-lane highway that everyone
shares. As the number of vehicles on the highway increases, the traffic
becomes congested and transit time increases for individual cars.
On a shared hub all nodes must operate at the same speed, either 10 Mbps
or 100 Mbps. Fast Ethernet repeaters provide 100 Mbps of available
bandwidth, ten times more than what's available with a 10BASE-T repeater.
Repeaters use a well-established, uncomplicated design, making them
highly cost effective for connecting PCs within a workgroup. These are the
most common type of Ethernet hubs in the installed base.
Switching hubs
In a switched network environment, each port gets a fixed, dedicated
amount of bandwidth. In the highway scenario, each car has its own lane on
a multi-lane highway and there is no sharing.
In a switched environment, data is sent only to the port that leads to the pro-
per destination station. Network bandwidth is not shared among all stations,
and each new station added to the switch gets access to the full bandwidth
of the network.
If a new user is added to a 100 Mbps switch, the new station receives its
own dedicated 100 Mbps link and doesn't impact the 100 Mbps bandwidth
of another station. Switches can effectively increase the overall bandwidth
available on the network, significantly improving performance. Switches
can also support full duplex.
For more information on Fast Ethernet, visit our Network Products web site
at http://www.intel.com/network.
30 Intel EtherExpress PRO/100+ TX PCI LAN Controller User's Guide