How a network is built: a layer-by-layer view

A network is not a single device but a set of connected layers. The weakest link in the chain determines the speed and reliability of the whole system, so it matters to think about each layer separately.

1. The internet and protection layer: router and firewall

The internet from your provider first enters a router or a firewall. The router is the network's “junction”: it hands out addresses to devices and sends traffic in the right direction. A firewall protects the company network from outside threats and uses rules to control which traffic may pass. For a small office one strong router may be enough, but as the number of staff and the security requirements grow, a separate firewall becomes important.

2. The distribution layer: the switch

A switch connects cable-attached devices (computers, printers, access points, cameras) to each other. There are two main kinds: an unmanaged switch works on a “plug and play” basis, while a managed switch lets you split the network into parts (VLANs), watch traffic and find problems quickly. A switch with PoE carries both data and electric power over the same cable, so cameras and access points need no separate adapter or socket.

3. The wireless layer: access points

The quality of Wi-Fi depends less on the power of the router than on the number of access points and how well they are placed. Instead of one powerful device, several access points spread evenly across the ceiling often give a more stable and faster result. Indoor and outdoor (weatherproof) models are designed for different spaces.

4. The physical layer: cabling

The layer that gets the least attention but causes the most problems is the cable. Poor-quality cable, a badly crimped connector or a route that was not laid properly later cause outages whose cause can never be found. We talk about this separately below.