Figure 1-4.—A ring network topology.
The Ring Network
In a ring network, all of the components or nodes
are connected to the main cable, and the cable forms a
ring, as shown in figure 1-4. This topology allows a
node to send a message to another node on the ring.
However, the message must be transmitted through
each node until it reaches its destination. Messages
proceed from node to node in one direction only.
Should anode fail on the network, data can no longer be
passed around the ring unless the failed node is either
physically or electronically bypassed. Using bypass
software, the network can withstand the failure of a
workstation by bypassing it and still be able to maintain
the network’s integrity. One of the major issues in a ring
topology is the need for ensuring all workstations have
equal access to the network.
One of the major disadvantages of ring topologies is
the extreme difficulty of adding new workstations while
the network is in operation. Normally, the entire
network has to be brought down while a new node is
added and cabling reattached. However, this particular
problem can be overcome by initially setting up the
network with additional connectors. These connectors
enable you to add or remove nodes while the network
remains intact and in operation. The addition of the
connectors is accomplished with the addition of a
multistation access unit (MAU). The MAU is a wiring
concentrator which allows workstations to be either
inserted or bypassed on the ring.
The Distributed Star (Tree) Network
The distributed star or tree topology (figure 1 -5) can
provide many of the advantages of the bus and the star
topologies. It connects workstations to a central point,
called a hub. This hub can support several workstations
or hubs which, in turn, can support other workstations.
Distributed star topologies can be easily adapted to the
physical arrangement of the facility site. If the site has a
high concentration of workstations in a given area, the
system can be configured to more closely resemble a
Figure 1-5.—A distributed star (tree) network topology.
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