1. Integración de Tecnologías
de la Información ABOUT NETWORKS
Carlos Alberto González García Página 1
Computer Networks
It is a set of two or more computers connected together to share resources.
Networks are classified as:
LAN.- Local Area Network, is a network that connects the computers in a relatively small area.
MAN.- Metropolitan Area Network, is a collection of LANs scattered in a city (tens of
kilometers).
WAN.- Wide Area Network, is a collection of geographically dispersed LANs hundred
kilometers from each other.
How to connect to a network??
To connect to a network requires devices such as:
Network Interface Card.
Bridges.
Gateways.
Routers.
Hub.
Repeaters.
HUB
Is a network computer that allows other computers connected together and forwards the
packets it receives to all others.
HUB types :
Active hubs: Regenerate and retransmit the signals of the same shape as a repeater.
Having from 8 to 12 ports, often called multiport repeaters. Electrical power required for
operation.
2. Integración de Tecnologías
de la Información ABOUT NETWORKS
Carlos Alberto González García Página 2
Passive Hubs: They act as connection points and do not amplify or regenerate the
signal, the signal passes through the hub.
Hubs hybrids: allow you to connect various types of cables.
Network cabling.
Are those wires for connecting computers to each other or network terminals.
They are classified into:
Coaxial.- Easy to handle, flexible, lightweight and inexpensive. Are composed of
copper wires, which form the core and are covered by an insulator, copper braiding or
metal and an outer covering, made of plastic, Teflon or rubber.
Twisted pair.- Are composed of two copper wires intertwined and isolated and can be
divided into two groups: shielded (STP) and unshielded (UTP).
Optical fiber.- Has a slender glass cylinder, called core, covered with a glass coating
and this is a lining of rubber or plastic.
3. Integración de Tecnologías
de la Información ABOUT NETWORKS
Carlos Alberto González García Página 3
Bus Topology.
Hubs: This topology allows all stations receive the information transmitted, a station transmits and
all other listening, The bus is passive, there is no regeneration of the signals at each node.
Network cabling: In this structure all network terminals are connected to a single cable that is
terminated with a dimmer. Ethernet.
Network Security: They are very susceptible to breakage of cable connectors and the cable shorts
that are very difficult to find.
Ring Topology.
Hubs: Stations are linked to one another in a circle through a common cable. Signals circulating in
one direction around the circle, regenerated at each node.
Network cabling: Token ring network uses a single cable with the difference that the cables are
connected such that they form a complete ring. Each terminal is connected directly to a central
device called a Media Access Unit (MAU).
Network Security: The token circulates around the ring and when a computer wants to send data,
wait for the token and positions it.
Star topology.
Hubs: are interconnected in a star level (many hubs connected to a central hub for high power) but
also concentrators may be connected in a bus configuration.
Network Cabling: This type of structure is based on connecting all terminals in the network to a
central processor element. This structure is also used for high-speed Ethernet (Fast Ethernet).
Network Security: If the hub fails, the entire network goes down.
