Node

Any device that is connected to a network.

Client

A node that requests and uses resources available from other nodes.

Server

A nodes that share resources with other nodes.

Host

Any computer that provides services and connection to other computers on a network.

Switch

A central node that coordinate the flow of data by sending messages directly between sender and receiver nodes.

Hub

The device that provides a common central connection for nodes on network.

Network Interface Cards (NIC)

Expansion cards located within the system unit that connect a computer a network.

A communication device that enables a computer or device to access a wired network (via cable).

Packets

Small pieces into which message are divided.

Topology

Bus Network

Star Network

Ring Network

Explanation

A bus network consists of a single central cable (backbone/trunk), to which all computers and other devices connect (node).

The bus is the physical cable that connects the computers and other devices.

The bus in a bus network transmit data, instructions, and information in both direction as a series of signal.

Those signals are sent as electrical pulses that travel along the length of the cable.

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.

All the computers and other devices on the network connect to a central device (hub/switch), 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 switch.

 Hub/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 and switch.

The hub takes a signal that comes from any device and passes it along to all other devices in the network.

On a ring network, a cable forms a closed loop (ring) with all computers and devices are arranged along the ring.

Data transmitted on a ring network travels from device to device around the entire ring, in one direction (clockwise or counter clockwise)

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 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.

Advantages

Network can easily be extended, by adding new node to the backbone.

Failure of a node, doesn’t affect the entire network.

No disruptions to the network when connecting and removing nodes.

Require less cable.

Bus network are inexpensive and easy to install.

Easy to expand the network. You only add node to the hub.

Failure of a node, doesn’t affect the entire network.

No disruptions to the network when connecting and removing nodes.

Easy to install and wire.

Require less cable.

No data collision exist between nodes.

The transmission of data is relatively simple as packets travel in one direction only.

Cable faults are easily located, making troubleshooting easier.

The uses of token passing enables all devices in a ring topology to share the network resources fairly.

Disadvantages

If the backbone cable fails, the entire network stop working.

Terminators are required at both ends of the backbone cable.

Network speed decrease when the number of nodes increase.

It is difficult to identify the problem if the entire network shut down.

If the hub fails, the entire network stop working

Require more cable.

Network speed decrease when the number of nodes increase.

If any node fails, the entire network stop working

There will be a limit on the distance between nodes.

Data packets must pass through every computer therefore, this makes it slower.

A ring network can span a larger distance than a bus network, but it is more difficult to move.