CHARACTERISTICS OF NETWORKS

TYPES OF NETWORKS

We can classify the different types of networks by following different rules.

By the scale:

-          LAN (Local Area Network)

-          WAN (Wide Area Network)

By the functional relation or architecture:

-          Client-Server: The computer server must offer a service to many computers who ask for it.

-          Peer to Peer (P2P): All the computers can be at the same time clients and servers so they don’t need a computer server (networks like Ares, Skype and instant messenger).

TOPOLOGY OF THE NETWORK

It is the way of physical and logical connection between different computers.

-          Bus topology: All computers are connected in parallel on a same line with only a cable.

-          Star topology: The computers are connected on a central node called “hub” with the form of a star.

THE MEANS OF TRANSMISSION

Cable transmission

-          Coaxial cable: Two cables with concentric conductors. The central cable (data transmission) has got an isolate layer and the second conductor recovers it like a mesh.  It can have a maximum velocity of 10 Mb/s.

-          Pair plait cable: Two copper isolated cables and plaited for reduce the interferences. It can have a maximum velocity of 1 GB/s.

-          Optical fibre:  Layers of glass and plastic. It transfers digital data using light impulses with a high velocity. . It can have a maximum velocity of 10 GB/s.

TRANSFERENCE VELOCITY

We measure it for the number of bits/second.

kbps o kb/s - quilobit for second                                                                  Mbps o Mb/s - megabit for second                                                                                             Gbps o Gb/s - gigabit for second

PHYSICAL ELEMENTS OF A LAN

-          Electronic Ethernet interface: Is the electronic target that all computers must have to connect on a network. The portable computers have got it on the base plate. The MAC (Media Access Control) is a code who identifies every computer. Everyone is different.

-          The hub: Is a device where other cables and specific concentrators are connected. This topology allows the creation of networks that are intercommunicated with concentrators.

-          The switch: Is an electronic device where we connect the computers for create a very long network with more data traffic and concentration than a hub.

-          RJ-45 connector: Allows the physical connection between a device and the cable.

-          The router: Is a device that connects a network and his devices to the Internet. It must adapt to the technology of the exterior connection. The domestic routers have got a ADSL connection, a switch and a point of Wi-Fi access.