What is a network topology?

When we think of a computer network, it’s common to imagine only the equipment that makes it up: routers, antennas, computers, phones, or cables. But there’s another equally important question:

How are these devices connected to each other?

The answer is given by the network topology.

A topology describes how devices are organized and how information flows between them. In other words, it represents the architecture of a network’s connections.

This organization influences aspects such as:

• the reliability of communication;
• how easily the network can expand;
• data transmission performance;
• fault tolerance;
• deployment and maintenance costs;
• how easy it is to operate during an emergency.

That’s why choosing a topology isn’t just a technical decision. It’s also a decision about how we want the network to respond when something stops working.

Why does this matter for this project?

Our project investigates communication technologies that could make up a toolkit for rapid response to climate-related incidents and disasters.

In these scenarios, communication tends to face several challenges:

• part of the infrastructure may be damaged;
• some equipment may be left without power;
• communities may become isolated;
• new areas requiring service may emerge quickly;
• the network may need to be set up temporarily and expanded as the situation evolves.

This means that how a network is organized can be just as important as the technology used to transmit it.

Wi-Fi, for example, can work in different topologies. Depending on how the network is organized, it can be simpler to install, easier to expand, or more resistant to equipment loss.

Main network topologies

Star topology

This is the most common topology in home networks and small offices.

In it, all devices connect to a single central piece of equipment, usually a router or Wi-Fi access point.

        Laptop
           │
Phone ─── Router ─── Computer
           │
        Printer

Advantages

• simple installation;
• easy administration;
• good performance in small networks;
• widely available equipment.

Limitations

All communication depends on the central equipment.

If it fails or loses power, communication between all devices can be interrupted.

In disaster situations, this dependency can represent a point of vulnerability.

Bus topology

It was widely used in early local networks.

All devices share the same physical communication medium.

PC ─── PC ─── PC ─── PC

Advantages

• low cost;
• small amount of cabling.

Limitations

A failure on the bus can interrupt all communication.

In addition, its performance decreases as new equipment is added.

Today it is rarely used.

Ring topology

Each device connects to its two neighboring devices, forming a closed circuit.

      PC
    /    \
PC          PC
    \    /
      PC

Messages travel around the ring until they reach their destination.

Advantages

• organized communication;
• few data collisions.

Limitations

An interruption in the ring can compromise all communication, depending on the technology used.

It’s also not a common topology in community networks.

Tree topology

It can be understood as a combination of several star topologies.

Each group of devices has a central piece of equipment, and these pieces of equipment are connected in a hierarchical structure.

             Main
          /         \
      Router      Router
      /     \      /     \
    PCs    PCs   PCs    PCs

Advantages

• makes it easier for the network to grow;
• allows different areas to be segmented.

Limitations

The equipment closest to the root of the tree becomes critical to the network’s operation.

Mesh topology

In mesh topology, there isn’t necessarily a single path for information to reach its destination.

Each piece of equipment can communicate with several others, creating different possible paths for data to travel.

          Nó
        / | \
      /   |   \
    Nó----+----Nó
     |\   |   /|
     | \  |  / |
     |  \ | /  |
     |   \|/   |
     |   /|\   |
     |  / | \  |
     | /  |  \ |
    Nó----+----Nó

When one path ceases to exist, routing protocols can automatically find another.

This characteristic is known as redundancy.

It makes the network more adaptable to change and more resistant to failures.

What is a mesh network?

Although the terms are often used as synonyms, there is an important difference.

Mesh is not just a physical topology.

It is also a network architecture based on collaboration among the network’s nodes.

Each device can act simultaneously as a client and as a message-forwarding point.

Rather than depending exclusively on a central piece of equipment, the devices themselves collaborate to keep communication working.

Projects such as LibreMesh use this architecture to build distributed community networks on top of conventional Wi-Fi equipment.

Topology doesn’t depend only on technology

An important point in this project is that topology is not determined solely by the technology used.

It also depends on:

• how the equipment is distributed across the territory;
• whether or not there is a central point;
• whether communication is continuous or intermittent;
• what the network’s purpose is;
• what resources are available (power, infrastructure, mobility).

This means that the same technology can operate in different topologies depending on the context.

How other technologies relate to topologies

Although this document uses Wi-Fi-based examples to illustrate concepts, other communication technologies also operate with specific topological structures.

LoRa

In LoRa systems, it’s common to have an organization in which devices send data to a central point called a gateway.

Sensor ─┐
Sensor ─┼── Gateway
Sensor ─┘

This model resembles an extended star topology, suitable for low-data-rate, long-range communication.

HT radios

Handheld radios (HTs) mainly operate through direct communication over a shared channel.

Radio ◄──► Radio ◄──► Radio

They can also be used with repeaters to extend range:

Radio ─ Repeater ─ Radio

Here, the topology is less rigid and more dependent on the operational use of the channel and the available infrastructure.

Why does this matter in disaster scenarios?

In floods, landslides, and fires, communication infrastructure may be partially damaged or constantly changing.

This directly affects the network’s topology.

• some nodes may stop working;
• new points may be installed temporarily;
• communication paths may change over time;
• different technologies may coexist in the same territory.

That’s why understanding topologies helps us think not only about how a network works under normal conditions, but also about how it adapts when conditions change.

Is there an ideal topology?

No.

Each topology responds to a specific set of needs:

• star: simplicity and centralized control;
• bus: simple, historical structure;
• ring: sequential flow organization;
• tree: hierarchy and structured expansion;
• mesh: flexibility and fault tolerance.

In disaster-response contexts, the challenge isn’t choosing a single topology, but understanding how different forms of organization can be combined or adapted according to the territory’s situation.

Closing

Network topology is not just a technical classification.

It’s a way of understanding how communication remains possible when infrastructure changes, fails, or needs to be rebuilt quickly.

In the context of this project, it is a tool for thinking of networks as living systems that reorganize themselves according to the territory and the needs of the people.