Ch.12.1 Sound Byte: Network Typology and Navigation Devices

Bus Topology: Part 3

- Passive topology: Devices connected to the bus do not move data along - Signals bounce along the length of the bus - Terminators prevent signals from bouncing back down the bus

What Is a Topology?

- Physical arrangement of computers, peripherals, and media (cable) - Like the floor plan of a building - Different topologies suit different needs

Star Topology: Part 1

- Switch - Central communications device - Connects nodes - Sends and receives to all other nodes - Active topology - Ethernet - Most common protocol for star networks

Describe the types of network navigation devices.

- Switches provide efficient communication on star networks. - Bridges transfer data between two collision domains on a single network. - Routers transfer data between two networks.

Network Navigation Devices

- Three major types - Switches - Bridges - Routers - Required by star networks - Using the correct device improves efficiency

Ring Topology: Part 2

- Token travels the ring - Device wishing to send data grabs token - Only device holding token can transmit data - Token is released back onto ring after data is sent

A topology can be compared to the ___________.

floor plan of a building

Tokens are used in a token ring network to ________.

prevent data collisions from occurring

An example of a network navigation device is a __________.

router

Describe the attributes of a ring topology.

- A ring topology uses a continuous circle of media (cable). - A special data packet called a token controls transmission of data. - It is an active topology: each node retransmits token. - There is fair allocation of network resources. - Failure of one computer will bring down entire network.

Describe the attributes of a star topology.

- A star topology features a central communications device (switch) that connects nodes and sends and receives data. - They are easy to expand, and failure of one computer doesn't bring down entire network. - They are more expensive to expand than other topologies.

Ring Topology: Part 3

- Active topology: each node retransmits token - Advantages - Fair allocation of network resources - Large numbers of computers don't affect performance - Disadvantages - Failure of one computer will bring down entire network

Star Topology: Part 3

- Advantages - Easy to expand - Failure of one computer/cable doesn't bring down entire network - Disadvantages - More expensive and requires more cable - Failure of switch cuts off all devices on that switch from network

Star Topology: Part 2

- Avoiding data collisions - Carrier Sense, Multiple Access with Collision Detection (CSMA/CD) - A jam signal is sent if collision occurs - Nodes retransmit data at random intervals

Bus Topology: Problems

- Cable breaks cut off computers from the network - Not suitable for large networks - Signal strength degrades over distance - Only one computer is able to communicate at a time​

Ring Topology: Part 1

- Continuous circle of media (cable) - Data flows in one direction only - Special data packet called a token controls transmission of data

Routers

- Designed to route data between networks - Often used to route data between an internal network and the Internet (an external network)​

Describe the attributes of a bus topology.

- In a bus topology, computing devices are connected in sequence on a single cable. - A break in the cable brings down the entire network. - Bus topology is cheap and easy to set up​.

Bridges

- Large networks are divided into collision domains to improve efficiency - Domains need to be connected - Bridges are designed to transfer data between collision domains

Switches

- Necessary on star networks for efficient communication - Retransmit data only to device that is to receive the data

​​Bus Topology: Part 2

- Only one computer can communicate at a time - Data collisions occur when two computers transmit at the same time: data is lost or damaged - Computers "listen" to make sure the bus is clear before transmitting - Data is transmitted to all devices connected to the bus

Explain what a network topology is.

- Topology refers to the physical layout of components on a computer network. - Just as buildings have different floor plans, networks have different blueprints delineating their layout. - Each topology has its own strengths and weaknesses.

Bus Topology: Part 1

Computers connected in sequence on a single cable​ - Most common in peer-to-peer networks (home networks or very small business networks)​ - No longer used often​​

Which of the following is NOT an advantage of star topology?

They are cheap to expand.

A bus network in which attached devices cannot move data along the bus is referred to as a(n) __________ topology.

passive