NETWORK TOPOLOGY

NETWORK TOPOLOGY

Definition : A network topology refers to the layout of the computers and devices in a communications network.

Physical topology : The arrangement of a cabling is the physical topology.
Logical topology : The path that data travels between computers on a network is the logical topology.

STAR TOPOLOGY

BUS TOPOLOGY

 STAR TOPOLOGY

CRITERIA	STAR TOPOLOGY	BUS TOPOLOGY	RING TOPOLOGY
Definition	All teh computers and other devices on the network connect to a central device,thus forming  a star.	A bus network consist of a single central cable (backbone),to which all computers and other devices connect.	On a ring network,a cable forma a closed lops (ring) with all computer and devices arranged along the ring.
Advantages	If on device fails,only that device is affected. Devices can be added to or removed from network with little or no disruption. Easy to troubleshoot and isolate problem.	Inexpencive to install. Other devices can be attached or detached without disturbing the network. Failure of one device usually does not affect the rest of the network.	Transmission of data is simple as packets travel in one direction only. Cable faults are easily located,making troubleshooting easier. All devices in ring topology share the network resources fairly.
Disadvantages	If the hub or switch fails,the entire network will be inoperable. Requires more cable than most of the other topologies. More expensive because cost of the hub/switch.	There might be disruption when computer or other devices are added or removed. The break in the main cable will prevent all systems from accessing teh network. It is difficult to identify the problem if the entire network shut   down.	Afailure in an cable or devices breaks the loop and can take down entire network. Data packets must pass through every computer,thus make it slower.

LAN,MAN & WAN

Different between Local Area Network (LAN),Metropolitan Area Network (MAN),Wide Area Network (WAN)

CRITERIA	LAN	MAN	WIDE
Area of coverage	Network cover limited gepgraphical area such as closely positioned group of building network,network ata home,network inside computer laboratory and network in office building.	A high speed network that connects LAN in a MAN such as a cities or town.	Network cover large geographical area such as countries,the continents or the world.
Network size	Small size (building).	Larger size (in a campus or cities)	Largest size (different states or counties).
Speed	Fastest in data transferring and access time.	Slower data transferring and access time.	Slowest data transferring and acces time.
Communication devices	Connected using modems,hubs,switch,router	Connected using modems,switch,hubs,router	The commectiion is made via satellite communication on link or via internet.
Cost	Less costly setup and maintenance.	More costly setup and maintenance.	Costliest setup and maintenance.
Network Ownership	Private – owned,controlled and manage by a single person or organization.	Private – owned and operated by a single entity such as a government or large corporation.	Not owned uo any one organzation but exist under collective or distributed ownership.
Examples	-Network inside the computer lab. -Network around school. -Network inside your home.	-Surveillance system -Traffic light monitoring system. -Cable Network TV.	-Car Navigatiion System -Video Conference -Intelligence Transportation System (ITS)
	LAN’S example can be an office whose different departments such as personnel,accounting ets are located in the same building connected via bus topology using Ethernet cards.	Example of MAN is bank whose different branches in a city like KL are connected  using public telephone exchange and the system are connected with each other using LAN within each branch and different branches ae connected usingodem and bridges.	WAN’s example is teh connection of various branches of American Insurance Group at different countries.These branches are linked using microwave satellite communication system or internet connection.Each branch has its own LAN circuit.