Telecommunications, P. I
Networks and Telecommunications
NETWORK – two or more computers
interconnected by a cable (or alternatively, by a
TELECOMMUNICATIONS - the electronic
movement of information.
Telecommunications, P. I:
Networks by degree of centralization:
– Peer-to-Peer vs. Client-Server networks
– Hub and Switches
Networks By Degree Of
A PEER-TO-PEER NETWORK treats all
computers equally and is used primarily in
A CLIENT/SERVER NETWORK is a network
that contains one or more host computers
(called “servers”) that provide some type of
service to the other computers (called
PC PC PC Shared
Internetwork Processor to Other Networks
Client/server networks are the
emerging blueprint for all networks
What are the benefits of client/server
How is the network connected?
WIRED MEDIA transmit information over a closed
path (such as a wire). Examples: twisted-pair cable
(copper), coaxial cable (copper), and fiber optic cable
WIRELESS MEDIA transmit information through
the air. Examples: infrared, terrestrial wireless,
TWISTED-PAIR CABLE - two insulated copper
wires twisted in a spiral. Transmissions are sent via
– Coaxial cable has shielding that reduces electrical
FIBER OPTIC CABLE - uses a very thin glass or
plastic fiber. Transmissions are pulses of light.
Question: What are the benefits of fiber optic cable?
INFRARED uses a red light (below the visibility of
the human eye) to transmit information (line of sight)
TERRESTRIAL WIRELESS transmit wireless
signals in a path between cell phone towers.
Question: What is a limitation of terrestrial wireless?
SATELLITE WIRELESS are basically wireless
transmission systems in space.
A Comparison Of Media
The capacity for information flow is called
BANDWIDTH. It is usually measured in
Medium Max Data Rate Max Range
Twisted Pair, Cat 3 10 Mbps 100 meters
Twisted Pair, Cat 5 100 Mbps 100 meters
Terrestrial Wireless 100s Mbps 20-30 miles
Satellite GEO 100s Mbps 8000 miles (1/3 the
Fiber Optic Cable 100s Gbps 100 miles
Key Considerations for Media
are the hardware devices that unite the various
media and computers and route data and
communications throughout a network.
1. HUBS AND SWITCHES – devices containing
ports that enable multiple cable connections. Each
computer on the network is connected by cable to the
hub or switch.
Hubs: Central Connection Points
Networking Devices, P. II
2. REPEATER – a device that gives your
network signals a boost.
3. MULTIPLEXER - aggregates several media
and allows them to share a single medium
that operates at a much higher capacity.
4. ROUTER – A networking device that
connects two or more networks: it routes
packets of data from one network to another.
The router ensures that information doesn't go
where it's not needed.
The router makes sure that information does
make it to the intended destination.