Network Topologies
Point-to-Point Topology
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Point-to-point (PTP) topology
connects two nodes directly together.
The following examples are pure
point to point links:
Two computers communicating via
modems.
A mainframe terminal communicating
with a front end processor.
A workstation communicating along a
parallel cable to a printer.
Star Topology
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The star topology is a popular method
of connecting the cabling in a computer
network. In a star, each device connects
to a central point via a point-to-point
link. Depending on the locical
architecture used, several names are
used for the central point includeing the
following:
Hub
Multipoint Repeater
Concentrator
Multi-Access Unit (MAU)
Ring Topology
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The Ring Topology is a physical, closed
loop consisting of point-to-point links.
In the diagram you can see how each
node on the ring acts as a repeater. It
receives a transmission from the
previous node and amplifies it before
passing it on.
Bus Topology
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In a Bus topology, all devices attach to
the same transmission medium. The
medium has a physical beginning and
end.All buses are implemented using
electrical cable, usually coax, and the
ends of the cable must be terminated
with a terminating resistor that matches
the impedance of the cable. The
terminating resistor prevents data
reflections from coming across as data
corruption. The bus is considered a
multipoint system because all devices
tap into the same backbone cable.
Hybrid Topology
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The Hybrid topology scheme combines
multiple topologies into one large
topology. The hybrid network is
common in large wide area networks.
Because each topology has its own
strengths and weaknesses, several
different types can be combined for
maximum effectiveness.
Coaxial Cable
UTP Cable
Ethernet
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An older, common wiring system for
Ethernet (10Base2) and (10Base5) uses
coaxial cable in a linear bus topology.
In the most common type of Ethernet,
each node connects to the coax through
a T-connector (BNC) that taps into the
signals on the coaxial cable. The nodes
both transmit and receive through the
same connector. Therefore, 10Base2
Ethernet is a logical as well as physical
bus.
Token Ring
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The adjacent figure shows the path that
a transmission follows through the
network. Starting at the hub, the signal
travels through a pair of wires to the
receive circuits on the node’s network
interface. The receive circuit passes the
signal to the transmit circuit, which
repeats the signal on a separate pair of
wires and sends the signal back to the
hub.
ARCnet
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ARCnet is wired in a star using coaxial
cable. The diagram adjacent shows an
extremely simple ARCnet using a
single passive hub.