The more twists per foot in a pair of wires the more

The more twists per foot in a pair of wires, the more resistant the pair will be
to cross-talk or noise, higher-quality, more expensive twisted-pair cable
contains more twists per foot
 Its relatively inexpensive, flexible and easy to install and it can span a
significant distance before requiring a repeater (a device that retransmits a
digital signal in its original form)
 Shielded Twisted Pair (STP): cable consists of twisted-pair wires that are
not only individually installed but also surrounded by a shielding made of a
metallic substance (ex. Foil), the shielding acts as a barrier to external
electromagnetic forces, thus preventing them from affecting the signals
traveling over the wire inside the shielding
 Unshielded Twisted Pair (UTP): consists of one or mote insulated wire
pairs encased in a plastic sheath, it doesn’t contain any additional shielding
for the twisted pairs, UTP is both less expensive and less resistant to noise
than STP
 Rollover Cable: whereas a crossover cable reverses the transmit and receive
wire pairs, a rollover cable reverses all the wires without regard to how they
are paired
o Also called Yost cables or Cisco console cables, they can be used
o Routers have two different ports:
 Ethernet port: allow for network communications and are the
type of port used to create LANs through the router
 Console port: used to communicate with the router itself, such
as when making programming changes to the device
 Copper Connectors and Couplers
o Connector: connects a cable to a network device, they are specific to a
particular media type, but you can integrate two media types by using
media converters
 Media converter: hardware the enables networks or segments
running on different media to interconnect and exchange
signals
o Coupler: passes data through a homogeneous connection without any
modification
 Ex. UTP connector: can connect 2 UTP cables
 PoE (Power over Ethernet): IEEE released its 802.3af standard which
specifies a method for supplying electrical power over twisted-pair Ethernet
connections
o The PoE standard specifies 2 types of devices:
 PSE (Power sourcing equipment): refers to the device that
provides the power, usually this device depends on backup
power sources

 PDs (powered devices): those that receive the power from the
PSE
Fiber-Optic Cable
 Contains one or several glass or plastic fibers at its center (core), data is
transmitted through the central fibers via pulsing light sent from a laser, or
an LED,