A network is simply a collection of computers or other hardware devices that are connected together
by communication channel that allow sharing of resources and information.
TYPE OF COMMUNICATION CHANNELS
The two major channels (media) are wired and wireless. Channels can be physical or non-physical path
over which information travels from its source to its destination through a telecommunication system. It could be called network links or lines.
The basis for either wired or wireless channel is electromagnetic spectrum which has frequency and wavelength.
TYPES OF NETWORK
LAN - Local Area Network
WLAN - Wireless Local Area Network
WAN - Wide Area Network
MAN - Metropolitan Area Network
SAN - Storage Area Network
CAN - Campus Area Network
LOCAL AREA NETWORK ( LAN )
The LAN connects network devices over a relatively short distance. A Network office building, school, or home usually contains a single LAN,
LANS are typically owned, controlled and managed by a single person or a small organisation.
WIDE AREA NETWORK ( WAN )
As the term implies, a WAN spans a large physical distance. The internet is the largest WAN, spanning the whole earth.
A WAN is a geographically dispersed collation of LAN s, through network devices called a routers. Most WANS are owned by collective or distributed ownership and management.
WANS tend to use technology like ATM, Frame, Relay and x-25 for connectivity over a longer distances. Residence typically employ one LAN and connect to the internet WAN
via an internet service provider ( ISP ) using a broad band modem. The ISP Provides a WAN IP address to the modem,
and all of the computers on the home network using LAN can communicate directly with each other but must go through a central gate way typically a broadband router to reach the ISP
WIRELESS LOCAL AREA NETWORK ( WLAN )
This is an extension of wide area network, without any physical connection between computers.
METROPOLITAN AREA NETWORK ( MAN )
A network spanning a physical area larger that a LAN, owned and operated by a single entity such as government body or large corporation. It is collection of LANs.
STORAGE AREA NETWORK ( SAN )
Within a city, SAN connect servers to data storage devices through a technology like fibre channel.
CAMPUS AREA NETWORK ( CAN )
A network spanning multiple LANs but smaller than a MAN, such as on a university or local business campus.
ARRANGEMENT OF NETWORK CONNECTIONS ( TOPOLOGY )
Network topology is the arrangement of computers on a network. These are three common types of network. They include:
1. Bus Topology
2. Star Topology
3. Ring Topology
BUS TOPOLOGY
BUS topology uses a common backbone to connect all devices. A single cable which is the backbone of BUS topology, functions as a shared communication
medium that devices attach or tap into with an interface connector. A device wanting to communicate with another device on the network sends a broadcast message
through the wire that all other devices have access to, but only the intended recipient actually accepts and processes the message.
See Screenshot Below:
RING TOPOLOGY
In a ring network, every device has exactly two neighbors for communication purpose. All messages travel through a ring in the same direction ( either
"clockwise" or "counterclockwise") a failure in any cable or device breaks the loop and can take down the entire network.
See Screenshot Below:
STAR TOPOLOGY
A network features a central connection point called a " hub node" that may be a network hub, switch or router.
Devices typically connect to the hub with un shielded twisted pair (UTD) Ethernet cable. Compared to the bus topology, a star network generally requires more cables
but a failure in any star network cable will only take down one computer network access and not the entire LAN ( if the hub fails however, the entire network also fails )
See Screenshot Below:
