Network Topologies

Content21. Definition of Topology

22. Types of topologies

23. How signals are sent--Student participation portion.

24. Pros and cons for each topology.

25. Check for Student Understanding.

Definition of Topology

A network topology is the physical layout of the local area network or transmission media.

Types of Topologies

Three topologies will be discussed.

y1. Bus

y2. Star

y3. Ring

This is the physical layout for a typical bus network.

A bus topology uses one long cable, called the backbone. Short cables, called drop cables, can be attached to the backbone using t- connectors. The backbone is terminated at both ends.

The Star Topology

MERCURY

VENUS

EARTH

MARS

JUPITERSATURN

URANUS

NEPTUNE

PLUTO

The star topology uses a central device with drop cables extending in all directions. It uses point to point links from a central hub, multiport or repeater.

The Ring Topology

Data PacketSour

ce

Destination

The Ring Topology

As the name suggests, the physical ring is a circular topology (or closed loop of point-to-point links). Each device connects directly to the ring or indirectly through an interface device and drop cable.

Source

Destination

A free token is routed around the ring. As it passes around the ring, it polls devices on the network to see if they want to transmit data.

How signals are sent. Student participation

section

Part One--student participation

1. Students will make a model of a bus topology by using the following items: gutter with caps, orange, and labels.

Part 2--Student Participation

Students will model a Star Topology using the following items.

1. lifesavers 2. fishing line 3. labels

4. doughnut shaped object to represent the hub, router, etc.

Part 3--Student Participation

Students will model a Ring Topology using the following items.

1. yarn

2. ring

3. clothing

Real life networks--Guess what?

Can you figure out what type of a topology was used in the following examples?

Advantages and DisadvantagesBus Topology

Advantages Disadvantages

Low cost to create High management cost

Less media used Difficult to troubleshoot

One goes down, doesn’t affect rest.

All units affected by media failure.

Advantages and Disadvantages

Star Topology

Easy to configure

Easy to troubleshoot

One goes down it doesn’t affect rest.

Advantages Disadvantagesmore costly-uses more mediaIf hub fails, entire network failsHub can become bottleneck

Advantages Disadvantages

Advantages and Disadvantages

Cable faults easily identified.It can span longer distances. Each host repeats and amplifies signal.

More difficult to install

media failure on a single unidirectional loop cause comple network failure

Ring Topology

Checking for Understanding

In this section the students will read a couple of senarios. The students will need to synthesize what they have learned and draw or depict the type of network topology that is needed for the given senario.