NETWORKING
· Computer devices/equipments
· transmission media to send/control data/signals,
· Communication devices to transmit/send data from sources
to destinations
· Software
LAN- LOCAL AREAS NETWORK
A Local area network (LAN) is a network that is confined to
a relatively small area. It is generally limited to a geographic area such as a
writing lab, school, or building. Rarely are LAN computers more than a mile
apart
WAN- WIDE AREA NETWORK
Wide Area Networks (WANs) connect larger geographic areas,
such as Johor Bahru, Malaysia, or the world. Dedicated transoceanic cabling or
satellite uplinks may be used to connect this type of network
MAN- METROPOLITAN AREA NETWORK
PAN- PERSONAL AREA NETWORK
MAN usually
is at home
TERMINAL & WORKSTATION
Terminals & workstation: Normally refers to data sources
and destinations. Example: Personal computers, terminals, workstations,
computers, Automatic teller machines (ATM)
TRANSMISSION MEDIA
Transmission media:
The physical media used to transmit data in a networked environment. It is also
use to transmit signal and electrical pulse through a medium. 2 types of
transmission media are bounded/guided and unbounded/unguided. Examples of
bounded media are twisted pair wire, coaxial cable and fiber optic cables.
Examples of unbounded are AM & FM radio, TV broadcasting, satellite
communication, microwave radio, infrared signals
NETWORK ELECTRONIC
Network electronic
devices are devices that control data transmission from sources to
destinations. It also act as interface between different transmission media or
communication protocol. For examples: Bridges, concentrators, routers, Front
End Processors, Private Branch, Switches Exchange (PBX), Hubs, Multiplexers,
and Gateways.
SOFTWARE
Software: At the
nodes, it involves techniques and protocols. Functions of the software are
measure the data transmits to the destination.
NETWORK ARCHITECTURE STANDARDS
Network architecture standards: Architecture is blueprint of
standards for a network consisting of items such as choice of media, media
interfaces, encoding methods, transmission protocols, routing protocols and so
on. It is needed to ensure interoperability between various devices and
equipment made by different vendors.
BRIDGES
A bridge device
filters data traffic at a network boundary. Bridges reduce the amount of
traffic on a LAN by dividing it into two segments.
Bridges operate at the data link layer (Layer 2) of the OSI
model. Bridges inspect incoming traffic and decide whether to forward or
discard it. An Ethernet bridge, for example, inspects each incoming Ethernet
frame - including the source and destination MAC addresses, and sometimes the
frame size - in making individual forwarding decisions.
Bridges serve a similar function as switches, that also
operate at Layer 2. Traditional bridges, though, support one network boundary,
whereas switches usually offer four or more hardware ports. Switches are
sometimes called "multi-port bridges" for this reason.
HUB
In computer networking, a hub is a small, simple,
inexpensive device that joins multiple computers together. Many network hubs
available today support the Ethernet standard. Other types including USB hubs
also exist, but Ethernet is the type traditionally used in home networking.
SWICTHES
A network switch is a small hardware device that joins
multiple computers together within one local area network (LAN). Technically,
network switches operate at layer two (Data Link Layer) of the OSI model.
PROTOCOL
Protocol specific a common set of rules and signal the
computers on the network use to communicate. Most networks use Ethernet, but
some networks may use IBM’s token Ring protocol
GATEWAYS
A gateway can translate information between different network
data formats or network architectures. It can translate TCP/IP to AppleTalk so
computers supporting TCP/IP can communicate with Apple brand computers. Most
gateways operate at the application layer, but can operate at the network or
session layer of the OSI model. Gateways will start at the lower level and
strip information until it gets to the required level and repackage the
information and work its way back toward the hardware layer of the OSI model.
To confuse issues, when talking about a router that is used to interface to
another network, the word gateway is often used. This does not mean the routing
machine is a gateway as defined here, although it could be.
ROUTERS
A router is used to route data packets between two networks.
It reads the information in each packet to tell where it is going. If it is
destined for an immediate network it has access to, it will strip the outer
packet, readdress the packet to the proper ethernet address, and transmit it on
that network. If it is destined for another network and must be sent to another
router, it will re-package the outer packet to be received by the next router
and send it to the next router. The section on routing explains the theory
behind this and how routing tables are used to help determine packet
destinations. Routing occurs at the network layer of the OSI model. They can
connect networks with different architectures such as Token Ring and Ethernet.
Although they can transform information at the data link level, routers cannot
transform information from one data format such as TCP/IP to another such as
IPX/SPX. Routers do not send broadcast packets or corrupted packets. If the
routing table does not indicate the proper address of a packet, the packet is
discarded.
InfraRed is a energy radiation with a frequency below our
eyes sensitivity, so we can not see it
Even that we can not "see" sound frequencies, we
know that it exist, we can listen them.
Even that we can not see or hear infrared, we can feel it at
our skin temperature sensors.
When you approach your hand to fire or warm element, you
will "feel" the heat, but you can't see it. You can see the fire
because it emits other types of radiation, visible to your eyes, but it also
emits lots of infrared that you can only feel in your skin.
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