NETWORK TOPOLOGY

WHAT IS NETWORK TOPOLOGY??

• 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.


TYPES OF NETWORK TOPOLOGIES

1. STAR TOPOLOGY

---- All the computers and other devices on the network connect to a central devices, thus forming a star.

---- 2 types of devices that provide a common central connection point to all the other devices on the network are a hub and a switch.

Hub/ Switch

• The device that provieds a common central connection point for aother 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.

ADVANTAGES AND DISADVANTAGES

ADVANTAGES	DISADVANTAGES
If one device fails, only that device is affected.	If the hub or switch fails, the entire network will be inoperable.
Devices can be added to or removed from network with little or no dicruption	Requires more cable than most of the other topologies.
Easy to troubleshoot and isolate problem	More expensive necause cost of the hub/switch

 2. BUS TOPOLOGY

---- A bus network consists of a single central cable (backbone), to which all computers and othe devices connect.

---- Bus topology uses coaxial cable as a backbone.

• 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 pukses that travels 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 and forth on 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 not match the device address, the data is accepted.
• All devices receive the data but only the receiving device accept them.

ADVANTAGES AND DISADVANTAGES

ADVANTAGES	DISADVANTAGES
Bus networks are inexpensive and easy to install.	There might be distruption when  computer or other devices are added or removed.
Computers and other devices can be attached and detached at any point on the bus without disturbing the rest of the network	Because all systems on the network connect to a single cable or backbone, a break in the cable will prevent all systems from accessing the network.
Failure of one device usually does not affect the rest of the bus network.	It is difficult to identify the problem if the entire network shut down

3. RING TOPOLOGY

---- On a ring network, a cable forms a closed loop( ring) with all the 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 ot 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 is allowed to send data.

ADVANTAGES AND DISADVANTAGES

ADVANTAGES	DISADVANTAGES
The transmission of data is relatively simple as packets travel in one direction only	A failure in any cable or device breaks the loop and can take down the entire network.
Cable faults are easily located, making troubleshooting easier.	Data packets must pass through every computer therefore, this makes it slower
The uses of token passing enables all devices in a ring topology to share the network resources fairly.	A ring network can span a larger distance than a bus network, but it is more difficult to install