NETWORKS
A network is two or more computers that are connected together.
Devices can be connected with communication links with it possible to share
information and resources.
On the network the device must follow a set of procedures called ‘protocol’ for
example TCP/IP.
In a network the computer doing different jobs that are:
oRouter that directs the traffic on the network.
oServer that stored data and enable other devices to access it.
oClient is any computer that receives data from a server.
Exist different types of networks for example:
oLAN
oWAN
oMAN
oVLAN
LAN stands for ‘local area network’ and connects devices within a limited area instead
WAN stands for ‘wide area network’ and connects devices over a large area, it can
cover more than one site or be spread across a country, or even the world.
Any device in a network is called ‘node’ and can be arranged in different topologies
that are the formation with the node are connected together.
The must use topologies are:
oBus topology – in this all nodes are connected to a central two-directional
cable that called ‘backbone’ where the data is sending. An advantage of this
topology is that it’s easy and cheaper to connect nodes to the network, but
drawbacks of these topology are if the backbone fails the whole network will be
fails, moreover another weak point of this topology is having one central cable
increases the chances of data collision.
oStar topology - here all nodes are connected to the central host computer
(switch) where all communications passes. The advantage of these
arrangements is if a node fails the whole networks doesn’t stops working,
moreover another advantage is that new nodes can be added to the network
simply. Instead, a drawback is the whole network fails if the switch fails,
moreover this topology can be expensive in a large network.
oRing topology - in this topology all nodes are connected in a circle, here the
nodes are at the same level that is called ‘peer-to-peer’ network. An advantage
of this topology is data passes around the network in one direction there are no
network collisions, but if any of the nodes fail, the ring is broken, and data
cannot be transmitted.
oMesh topology – in this topology every computer is connected to every other
computer by a separate cable, there is no central connection point. One
advantage is that the message can be received more quickly, but many times
mesh topologies cannot be used for the high number of connections.
