Classification of Physical Topologies

Point-to-point
The simplest topology is a permanent link between two
endpoints. Switched point-to-point topologies are the
basic model of conventional telephony. The value of a
permanent point-to-point network is the value of
guaranteed, or nearly so, communications between the two
endpoints. The value of an on-demand point-to-point
connection is proportional to the number of potential
pairs of subscribers, and has been expressed as
Metcalfe's Law.
Bus
Linear busThe type of network topology in which all of the nodes
of the network are connected to a common transmission
medium which has exactly two endpoints (this is the
'bus', which is also commonly referred to as the
backbone, or trunk) – all data that is transmitted
between nodes in the network is transmitted over this
common transmission medium and is able to be received by
all nodes in the network virtually simultaneously
(disregarding propagation delays)
Distributed bus
The type of network topology in which all of the nodes
of the network are connected to a common transmission
medium which has more than two endpoints that are
created by adding branches to the main section of the
transmission medium – the physical distributed bus
topology functions in exactly the same fashion as the
physical linear bus topology (i.e., all nodes share a
common transmission medium).
Star
The type of network topology in which each of the nodes
of the network is connected to a central node with a
point-to-point link in a 'hub' and 'spoke' fashion, the
central node being the 'hub' and the nodes that are
attached to the central node being the 'spokes' (e.g., a
collection of point-to-point links from the peripheral
nodes that converge at a central node) – all data that
is transmitted between nodes in the network is
transmitted to this central node, which is usually some
type of device that then retransmits the data to some or
all of the other nodes in the network, although the
central node may also be a simple common connection
point (such as a 'punch-down' block) without any active
device to repeat the signals.
Ring
The type of network topology in which each of the nodes
of the network is connected to two other nodes in the
network and with the first and last nodes being
connected to each other, forming a ring – all data that
is transmitted between nodes in the network travels from
one node to the next node in a circular manner and the
data generally flows in a single direction only.
Mesh
The value of fully meshed networks is proportional to
the exponent of the number of subscribers, assuming that
communicating groups of any two endpoints, up to and
including all the endpoints, is approximated by Reed's
Law.Tree (also known as hierarchical):The type of network topology in which a central 'root'
node (the top level of the hierarchy) is connected to
one or more other nodes that are one level lower in the
hierarchy (i.e., the second level) with a point-to-point
link between each of the second level nodes and the top
level central 'root' node, while each of the second
level nodes that are connected to the top level central
'root' node will also have one or more other nodes that
are one level lower in the hierarchy (i.e., the third
level) connected to it, also with a point-to-point link,
the top level central 'root' node being the only node
that has no other node above it in the hierarchy – the
hierarchy of the tree is symmetrical, each node in the
network having a specific fixed number, f, of nodes
connected to it at the next lower level in the
hierarchy, the number, f, being referred to as the
'branching factor' of the hierarchical tree.