Page 99 - DCAP104_EXPOSURE_TO_COMPUTER_DISCPLINES

Exposure to Computer Disciplines

Notes one of the paths fails. This decentralization is often used to advantage to compensate for
the single-point-failure disadvantage that is present when using a single device as a central
node (e.g., in star and tree networks). A special kind of mesh, limiting the number of
hops between two nodes, is a hypercube. The number of arbitrary forks in mesh networks
makes them more difficult to design and implement, but their decentralized nature makes
them very useful. This is similar in some ways to a grid network, where a linear or ring
topology is used to connect systems in multiple directions. A multi-dimensional ring has
a toroidal topology, for instance.

A fully connected network, complete topology or full mesh topology is a network topology
in which there is a direct link between all pairs of nodes. In a fully connected network with n
nodes, there are n(n-1)/2 direct links. Networks designed with this topology are usually very
expensive to set up, but provide a high degree of reliability due to the multiple paths for data
that are provided by the large number of redundant links between nodes. This topology is
mostly seen in military applications. However, it can also be seen in the file sharing protocol
BitTorrent in which users connect to other users in the “swarm” by allowing each user sharing
the file to connect to other users also involved. Often in actual usage of BitTorrent any given
individual node is rarely connected to every single other node as in a true fully connected
network but the protocol does allow for the possibility for any one node to connect to any
other node when sharing files.

Figure 5.11: Decentralization Network Topology

Hybrids
Hybrid networks use a combination of any two or more topologies in such a way that the resulting
network does not exhibit one of the standard topologies (e.g., bus, star, ring, etc.). For example, a
tree network connected to a tree network is still a tree network, but two star networks connected
together exhibit a hybrid network topology. A hybrid topology is always produced when two
different basic network topologies are connected. Two common examples for Hybrid network
are: star ring network and star bus network
 A Star Ring network consists of two or more star topologies connected using a multistation
access unit (MAU) as a centralized hub.
 A Star Bus network consists of two or more star topologies connected using a bus trunk
(the bus trunk serves as the network's backbone).

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