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WHAT IS NETWORK TOPOLOGY?

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

• It refers to both the physical and logical layout of a 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.  

Type of Network Topology :	Explaination :
Star Topology	·         All the computers and other devices on the network connect to a central device, thus forming a star. ·         Two types of devices that provide a common central connection point to all the other devices on the network are a hub and a switch. ·         The device that provides a common central connection point for other devices on a network. ·         All data that transfers from one device to another passes through the hub or switch. ·         The hub/switch takes a signal that comes from any device and passes it along to all the other devices in the network.
Bus Topology	•      The bus is the physical cable that connects the computers and other devices. •      The bus in a bus network transmit data, instructions, and information  as a series of signal. •      Those signals are sent as electrical pulses that travel along the length of the cable in all directions. •      Each devices is connected to the single bus cable through T-Connector. •      A terminator is required at each end of the bus cable to prevent the signal from bouncing back and forth on the bus cable. •      When a sending device transmits data, the address of the receiving device is included with the transmission. •      If the device address does not match the intended address for the data, the device ignores the data. •      If the data does match the device address, the   data is accepted. •      All devices receive the data but only the receiving   device accept them.
Ring Topology	·         On a ring network, a cable forms a closed loop (ring) with all computers and devices arranged along the ring. ·         Data transmitted on a ring network travels from device to device around the entire ring, in one direction (clockwise or counterclockwise). ·         Token passing is one method for sending data around a ring. ·         Each device takes a turn sending and receiving information through the use of a token. ·         The token along with any data is sent from the first device to the second device which extracts the data addressed to it and adds any data it wishes to send. ·         Then second device passes the token and data to the third device, etc. until it comes back around to the first device again. ·         Only the device with the token is allowed to send data. ·         All other devices must wait for the token to come to them. ·

Classification of Network :

LAN : Local Area Network

MAN : Metropolitan Area Network

WAN : Wide Area Network

Do You Know , How are LAN, MAN, and WAN different?

	LAN	MAN	WAN
Definition	-A LAN is a network that connects computers and devices in a limited geographical area.	-MAN is a high-speed network that connects local area networks (LAN) in a metropolitan area such as a city or town	- A WAN is a network that covers a large geographic area (such as a city, country, or the world) using a communications channel that combines many types of media such as telephone lines, cables, and radio waves
Example	q A home q School computer        laboratory Office building or closely positioned group of buildings.	Traffic Light , Monitoring System, Cable Network TV, Surveillance System and Building in a city.	They can cover a very large geographical area : states, countries ,continents.
Description	-The simplest form of LAN is to connect two computers together or connection of the computers and devices in the office or home. -A network which consists of less than 500 interconnected devices across several buildings, is still recognized as a LAN.	- Handles the bulk of communications activity across that region. -A MAN is optimized for a larger geographical area than a LAN, ranging from several blocks of buildings to entire cities. -A MAN might be owned and operated by a single organization, but it usually will be used by many individuals and organizations. -MAN can span up to 50km, devices used are modem and wire/cable.	The Internet is the world’s largest WAN
Characteries	-They are used within small areas (such as in an office building). -Limited to specific geographical area less than 2 km supporting high speed network . -They provide access for many devices. - They offer high-speed communication—typically 100Mbps or faster. - They use LAN- specific equipment such as hubs, switches, and network interface cards.	-It generally covers towns and cities. -With the advent of MANs, historically slow connections (56Kbps–1.5Mbps) have given way     to communication at hundreds of megabits per second and even gigabit speeds. - Transmission medium used for MAN are optical fibers, cables etc. -They use devices such as routers, telephone switches, and microwave antennas as parts of their communication infrastructure.	-They usually communicate at slower speeds (compared to LANs and MAN). -Communication medium used are satellite, public telephone networks which are connected by routers. -Routers forward packets from one to another a route from the sender to the receiver.
Diagram

	LAN	MAN	WAN
Advantages	-Easy to share devices (printers, scanners, external drives) -Easy to share data (homework, pictures) -Cost of LAN Setup is low. -Sharing of resources such as printers hence cost effective.	-Efficiency and shared access. -All the computer-owning residents of the area have equal ability to go on line.	-Messages can be sent very quickly to anyone else on the network. -Everyone on the network can use the same data. This avoids problems where some users may have older information than others. -Share information/files over a larger area.
Disadvantages	-Power - a good LAN is required to be on all the times. -Security - each computer and device   become another point of entry for undesirables. -If all computers running at once, can reduce speed for each. -Area covered is limited	-It can be costly (hardware, software, support, etc.) -Security problems -As the network consists of many computers over the span of a city, the connection can lag or become quite slow.	-Setting up a network can be an expensive and complicated experience. -Security problems because exposed to viruses and hackers. -Maintenance problems. Large enterprises will dedicate personnel to maintaining their WAN.