770  Network Topology Interactive Tools and Visualizer

770.1 Learning Objectives

By the end of this section, you will be able to:

  • Use Interactive Visualizers: Experiment with different topology configurations
  • Compare Topology Metrics: Observe connection counts, failure modes, and performance
  • Visualize Physical Topologies: Understand building floor plans and device placement
  • Apply Knowledge to Scenarios: Test understanding through scenario-based questions

770.2 Prerequisites

770.3 Interactive Topology Visualizer

TipInteractive: Network Topology Visualizer

Experiment with different network topologies to understand their characteristics and trade-offs for IoT deployments.

<label style="font-weight: 600;">
  Select Topology:
  <select id="topo-select" onchange="drawTopology()" style="padding: 5px 10px; border-radius: 4px; border: 1px solid #ccc; font-size: 14px;">
    <option value="star">Star</option>
    <option value="mesh">Full Mesh</option>
    <option value="partial-mesh">Partial Mesh</option>
    <option value="tree">Tree (Hierarchical)</option>
    <option value="ring">Ring</option>
    <option value="bus">Bus</option>
  </select>
</label>
<label style="font-weight: 600;">
  Number of Nodes:
  <input type="range" id="node-count" min="3" max="12" value="6" onchange="updateNodeCount(); drawTopology();" style="vertical-align: middle;">
  <span id="node-display" style="display: inline-block; min-width: 25px; font-weight: bold; color: #16A085;">6</span>
</label>
<button onclick="drawTopology()" style="padding: 5px 15px; background: #16A085; color: white; border: none; border-radius: 4px; cursor: pointer; font-weight: 600;">Redraw</button>

<h4 style="margin-top: 0; color: #2C3E50;">Topology Characteristics</h4>
<div id="topo-details"></div>

Key Insights for IoT:

  • Star topology is ideal for simple deployments where all devices can reach a central gateway (smart homes, office sensors)
  • Mesh topology provides self-healing for critical applications but scales poorly beyond ~100 nodes due to connection overhead
  • Tree topology efficiently aggregates traffic in large facilities by organizing devices hierarchically
  • Partial mesh balances redundancy and cost by protecting only critical communication paths
  • Bus and Ring are rarely used in modern wireless IoT but remain common in wired industrial systems (CAN bus, I2C)

Design Rule of Thumb: Start with star for simplicity. Use mesh when reliability trumps cost. Choose tree for large-scale hierarchical deployments.

770.4 Physical Topologies

Physical topology examples showing building floor plans with actual device locations, cable routing paths, distance measurements, and wireless coverage zones marked, demonstrating real-world spatial constraints
Figure 770.1: Physical topology examples showing actual device placement and cable layouts

770.4.1 Purpose and Features

Physical topology shows actual layout of network in real space.

Includes: - Building floor plans - Device locations (to scale) - Cable routes and lengths - Wireless coverage areas - Wall materials (for RF planning) - Data points and outlets

770.4.2 Physical Topology Example

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graph TD
    subgraph Building["Office Building - Floor Plan"]
        Room1["Room 101<br/>Switch SW1<br/>(Northwest corner)"]
        Room2["Room 102<br/>Sensor S1<br/>(12m from SW1)"]
        Room3["Room 103<br/>Sensor S2<br/>(25m from SW1)"]
        Room4["Room 104<br/>Camera C1<br/>(18m from SW1)"]
        Hall["Hallway<br/>Access Point AP1<br/>(Central location)"]
        Server["Server Room<br/>Gateway GW1<br/>(45m cable to SW1)"]
    end

    Room1 -.->|"12m Ethernet<br/>through ceiling"| Room2
    Room1 -.->|"25m Ethernet<br/>through conduit"| Room3
    Room1 -.->|"18m Ethernet"| Room4
    Room1 -.->|"8m Ethernet"| Hall
    Room1 -.->|"45m Fiber<br/>through walls"| Server

    style Room1 fill:#E67E22,stroke:#2C3E50,stroke-width:2px,color:#fff
    style Room2 fill:#16A085,stroke:#2C3E50,stroke-width:2px,color:#fff
    style Room3 fill:#16A085,stroke:#2C3E50,stroke-width:2px,color:#fff
    style Room4 fill:#16A085,stroke:#2C3E50,stroke-width:2px,color:#fff
    style Hall fill:#16A085,stroke:#2C3E50,stroke-width:2px,color:#fff
    style Server fill:#2C3E50,stroke:#16A085,stroke-width:2px,color:#fff
    style Building fill:#f0f0f0,stroke:#7F8C8D,stroke-width:3px

Key differences from logical: - Drawn to scale (or dimensioned) - Shows actual physical locations - Includes building structure - Cable routes show actual paths (not straight lines)

770.4.3 IoT Physical Topology Considerations

In IoT environments, physical topology shows:

  1. Sensor/actuator exact locations
    • Temperature sensors on exterior walls
    • Motion detectors at entry points
    • Smart lights in ceiling grid
  2. Wireless coverage optimization
    • Wi-Fi access point placement
    • LoRa gateway coverage areas
    • Zigbee mesh node distribution
  3. Power and connectivity
    • PoE (Power over Ethernet) cable runs
    • Power outlet locations
    • Battery-powered device accessibility
  4. Environmental factors
    • Wall materials (concrete blocks wireless signals)
    • Metal structures (interference)
    • Distance limitations for protocols

770.5 Knowledge Check Questions

Question 1: Why is a pure star topology usually a poor choice for a multi-floor building automation deployment with concrete walls?

Explanation: B. In real buildings, RF attenuation and floor-to-floor propagation mean a single gateway may not reach all nodes reliably. Mesh/partial-mesh designs add multi-hop paths and self-healing to route around dead zones and failures.

Question 2: In a mesh-based IoT network, what enables “self-healing” after a relay node fails?

Explanation: C. Self-healing comes from distributed routing: when a node or link drops, neighbors detect it and reroute through other relays (often with protocols like AODV-style path discovery in mesh stacks).

Question 3: Why is LoRa often inappropriate for indoor building automation that requires mesh self-healing?

Explanation: A. LoRa excels at long-range, low-power, gateway-centric telemetry, but most LoRaWAN deployments don’t support end-device mesh routing. Building automation often needs dense, indoor, multi-hop resilience (e.g., Zigbee/Thread meshes).

Question 4: A network administrator is documenting an IoT deployment. The physical topology shows sensors scattered across a warehouse floor plan with exact locations and cable runs. The logical topology shows a star pattern with all sensors connected to a central switch. Why might the physical and logical topologies appear so different?

Explanation: Physical and logical topologies serve different purposes and are intentionally different:

Physical Topology (Floor Plan View): - Shows exact locations, cable routes, distances, room layout - Used by installers, facility managers, maintenance

Logical Topology (Network View): - Shows connections, data flow, network hierarchy - Used by network engineers, troubleshooters, architects

Why they differ:

Aspect Physical Logical
Purpose Installation & maintenance Network operation & troubleshooting
Scale Drawn to scale Not to scale
Cable paths Actual routes (walls, conduits) Straight lines (connections only)
Distance info Yes (e.g., “25m cable run”) No
Building structure Walls, rooms, floors Not shown
Focus WHERE things are HOW things connect

770.6 Summary

  • Interactive visualizer helps understand topology characteristics through hands-on experimentation
  • Connection formulas: Star = n, Ring = n, Mesh = n(n-1)/2, Tree = n-1
  • Physical topology shows actual device locations, cable routes, and building layouts
  • Logical topology shows network connections independent of physical placement
  • Both views needed for complete IoT network documentation

770.7 What’s Next

Continue to Topology Hands-On Lab for a complete ESP32-based simulation where you can build star, mesh, and tree topologies, compare their routing behavior, and test failure scenarios in real code.