4 WiFi Topologies and Network Design

WiFi Topologies

Creating Large Wireless Networks

  • Setting up WiFi networks requires careful planning compared to wired Ethernet.

  • Ensuring coverage of a large area is a key consideration.

  • The WiFi network must connect to the broader network (e.g., the Internet or a LAN).

Basic Service Set (BSS)

  • A BSS is a fundamental building block of a WiFi network.

  • Independent BSS (ad-hoc network):

  • Infrastructure BSS:

Extended Service Set (ESS)

  • An ESS extends the range and mobility of a WiFi network.

  • It comprises multiple infrastructure BSSs.

  • APs communicate to forward traffic between BSSs.

  • APs communicate via a distribution system (LAN).

  • Devices perceive a single Layer 2 connection, simplifying network access.

  • Roaming between different ESSs is not supported by the 802.11 protocol and requires higher-level protocols like Mobile IP.

NetSpot Example

Planning Example (2.4 GHz)

Attenuation

  • Walls significantly attenuate WiFi signals.

  • 3 dB3 \, \text{dB} attenuation means the signal strength is halved.

  • 6 dB6 \, \text{dB} attenuation means the signal strength is reduced to 1/41/4.

  • Attenuation is more pronounced at 5 GHz compared to 2.4 GHz.

  • from liveport.com/wifi-signal-attenuation

Improving WiFi Performance

  • Upgrade to newer WiFi standards like 802.11ac or 802.11ax for better performance.

  • Optimize AP placement:

    • Minimize the number of walls between AP and devices.

    • Mount APs on the ceiling or high up to reduce obstacles.

    • Avoid placing APs in closets or enclosed spaces.

  • Eliminate interference:

    • Identify and remove other devices operating on the same frequencies (Bluetooth, cordless phones, microwave ovens).

  • Use directional antennas to focus and strengthen signals in specific areas.

Reducing WiFi Demand

  • Never place a server on a WiFi network.

    • All devices communicate through the AP, sharing the same medium.

    • A server doubles the traffic in the WiFi network, reducing performance for other devices.

  • Provide sufficient wired Ethernet sockets.

    • Don't rely solely on WiFi.

    • Use wired connections for high-bandwidth hardware or when WiFi is problematic. (like for the server)

Summary

  • Simple WiFi networks consist of a Basic Service Set (BSS) with an access point and client devices.

  • Extended Service Sets (ESS) connect multiple BSSs using the same Service Set Identifier (SSID or network name).

  • ESS allows devices to roam seamlessly between BSSs without losing connections.

  • Designing a WiFi network requires careful consideration and planning.