Page 93 - DCAP104_EXPOSURE_TO_COMPUTER_DISCPLINES

Exposure to Computer Disciplines

Notes
(1) All of the endpoints of the common transmission medium are normally
terminated with a device called a ‘terminator’.
(2) The physical linear bus topology is sometimes considered to be a special
case of the physical distributed bus topology — i.e., a distributed bus with
no branching segments.

(3) The physical distributed bus topology is sometimes incorrectly referred to
as a physical tree topology — however, although the physical distributed
bus topology resembles the physical tree topology, it differs from the
physical tree topology in that there is no central node to which any other
nodes are connected, since this hierarchical functionality is replaced by
the common bus.

Star Network Topology
In local area networks with a star topology, each network host is connected to a central hub.
In contrast to the bus topology, the star topology connects each node to the hub with a point-
to-point connection. All traffic that traverses the network passes through the central hub. The
hub acts as a signal booster or repeater. The star topology is considered the easiest topology
to design and implement. An advantage of the star topology is the simplicity of adding
additional nodes. The primary disadvantage of the star topology is that the hub represents
a single point of failure.

Figure 5.5: The Star Topology

Concentrator/Hub

Notes

 A point-to-point link (described above) is sometimes categorized as a
special instance of the physical star topology — therefore, the simplest
type of network that is based upon the physical star topology would
consist of one node with a single point-to-point link to a second node,
the choice of which node is the ‘hub’ and which node is the ‘spoke’ being
arbitrary.
 Star networks may also be described as either broadcast multi-access
or nonbroadcast multi-access (NBMA), depending on whether the
technology of the network either automatically propagates a signal at
the hub to all spokes, or only addresses individual spokes with each
communication.

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