Information Technology Reference
In-Depth Information
10 or 100BaseT shared hub
To other
hubs
Original packet
transmitted
from this
workstation
Repeated
packets to all
other hub ports
FIGURE 2.2
In a 10 or 100BaseT shared hub, transmission by a station first goes to the hub, which then
repeats (retransmits) the signal to all of the other connected stations.
A 10/100BaseT hub (or switch) typically has 8, 12, 24, or even more dual speed
10/100BaseT ports. Dual speed hubs usually sense the speed of the connected device,
and adjust accordingly. The hub/switch is capable of converting dissimilar speeds
between any two or more ports. A typical hub may be a stand-alone unit, or part of
a chassis with plug-in hub cards. Older stand-alone hubs usually had one port each
for thicknet and thinnet connections, in addition to the 10/100BaseT ports, but these
legacy ports are now uncommon. To recognize these legacy ports is easy: The thick-
net port has an attachment unit interface (AUI) and the thinnet port has a bayonet
naval connector (BNC). (See the Appendix for more on legacy cabling.)
Hubs may be used in combination together to build bigger networks by inter-
connection through one of the 10/100BaseT ports, or through a thicknet port or a
thinnet port if provided with one of these legacy ports. The 10/100BaseT interfaces
can be converted to AUI or thinnet interfaces or even fiber-optic links with appro-
priate transceivers or repeaters.
The active hub gives 10/100BaseT some unique advantages over the coax
topologies. Because each hub port is repeated to the rest of the network, each
10/100BaseT port is independent of the others. This means that the cable length of
a given port is not affected by the cable length of any other port. It is much simpler
to plan and test a 10/100BaseT network, because the cable length for a port must
