Exploring Network Topologies 27
FigurE 2.1 Bus topology
Data Busburns out or is removed. Although not seen in its purest form in today’s networks, the con-
cept still applies to particular segments.
Ring Ring topologies (Figure 2.2) are as true to their names as bus layouts. Essentially the
backbone, or common connector of the network, is looped into a ring; some ring layouts
use a concentric circle design to provide redundancy if one ring fails. Each client or node
attaches to the ring and delivers packets according to its designated turn or the availability
of the token. As you can see in Figure 2.2, a concentric circle design provides redundancy;
though a good idea, a redundant second ring is not required for the network to function
properly. The redundant ring architecture is typically seen in setups that use Fiber Distrib-
uted Data Interface (FDDI).
Star The star layout (Figure 2.3) is one of the most common because of its ease of setup
and isolation of connectivity problems should an issue arise. A star topology attaches mul-
tiple nodes to a centralized network device that ties the network together. Think of it as
looking like an old-style wagon wheel or the wheels on a bike. The hub is the centerpiece
of the wheel, and the spokes of the wheel are the legs of the star. The center could be a hub
or a switch; as long as it acts as a central point of connection, you have a star topology.
Stars are popular for numerous reasons, but the biggest reason has long been its resistance
to outages. Unlike nodes in bus and ring topologies, a single node of a star can go offline
without affecting other nodes.