Networking Fundamentals: Who Connects to Whom?

A network lets computing devices exchange data.

Before you analyze packets, you need a map of the devices that move them.

Start with four ideas:

• LAN: a local network covering a limited area
• WAN: a network connecting systems across larger distances
• switch: connects devices inside a local network and forwards frames toward the appropriate local destination
• router: connects different networks and forwards packets between them

Build a school-lab network

A fictional classroom contains:

• 12 Chromebooks
• teacher laptop
• wireless access point
• switch
• router/firewall
• printer
• local lab server
• internet connection

Draw a topology showing how they connect.

Do not draw every device directly to the internet. Show the intermediate network devices.

Topology describes relationships

Common conceptual topologies include:

• star
• bus
• ring
• mesh

Modern local networks often resemble a star around switches or wireless infrastructure, but the important skill is reading which device depends on which path.

Failure analysis

For your topology, evaluate:

Switch failure

Which local devices lose communication?

Router failure

Can local devices still communicate with one another? Can they reach external networks?

Access-point failure

Which devices are affected?

Lab-server failure

Does the whole network fail, or only the service hosted there?

This separates network availability from application availability.

Security boundaries

Network devices can also enforce boundaries.

Examples:

• guest network separated from internal devices
• firewall rules limiting traffic
• lower-trust IoT segment separated from laptops
• lab systems isolated from production systems

A topology diagram becomes a security diagram when you mark trust and control boundaries.

LAN versus WAN reasoning

Classify each scenario:

• Chromebook to printer in the same classroom network
• school building to district data center
• laptop to public website
• two devices connected to the same local switch

Explain which parts of the path are local and where routing between networks occurs.

Build a path trace

Trace this request conceptually:

Student Chromebook opens a public course website.

Possible path:

Chromebook → wireless access point → local network/switching → router/firewall → internet/WAN → remote server

For each stage, identify what the device contributes.

Evidence for Lesson 1

Submit:

• labeled classroom topology
• four failure analyses
• trust-boundary annotations
• one complete path trace

Finish with:

The router matters because it connects ________, while the switch mainly helps connect ________.

Networking becomes understandable when you can draw the path instead of treating "the internet" as one cloud.