determines
optimum stock levels, and coordinates a supply chain management system. In
this situation, a hierarchical network might be used, because it mirrors the actual
operational flow in the organization.
One disadvantage of a
hierarchical network is
that if a business adds
additional processing levels,
the network becomes
more complex and expensive
to operate and maintain.
Hierarchical
networks were often used
in traditional mainframebased
systems, but are
much less common today.
BUS NETWORK In a bus
network, as shown in
Figure 10-35, a single
communication path connects
the central server,
departmental servers,
workstations, and peripheral
devices. Information
is transmitted in either
direction between networked
devices, and all
messages travel over the
same central bus. Bus
networks require less
cabling than other topologies,
because only a single
cable is used. Devices
can also be attached or
detached from the network
at any point without
disturbing the rest of the network. In addition, a failure in one workstation on the
network does not necessarily affect other workstations on the network.
One major disadvantage of a bus network is that if the central bus becomes damaged
or defective, the entire network shuts down. Another disadvantage is that overall
performance declines as more users and devices are added, because all message
traffic must flow along the central bus. This does not occur in the treelike structure
of a hierarchical network or the hub-and-spoke design of a star network, where network
paths are more isolated and independent.
The bus network is one of the oldest LAN topologies, and is a simple way to connect
multiple workstations. Before the proliferation of star networks, bus networks were very
common. Today, the bus design is much less popular, but some firms have retained bus
networks to avoid the expense of new wiring and hardware.
RING NETWORK A ring network, as shown in Figure 10-36 on the next page, resembles
a circle where the data flows in only one direction from one device to the next. In
function, a ring network can be thought of as a bus network with the ends connected.
One disadvantage of a ring network is that if a network device (such as a PC or a