How to ensure WiFi clients can roam seamlessly?

Networks often consist of multiple Access Points to provide full WiFi coverage throughout a large area. WiFi clients may need to be able to freely move around without disrupting Internet applications such as VoIP calls, music & video streaming. Seamless roaming can be achieved by adjusting your WAN settings in the Plasma Cloud console as well as some other configurations.

The 802.11r, 802.11k and 802.11v WiFi standards are supported and enabled by default on APs running firmware 3.5.x or newer.

This article explains how to ensure WiFi clients can roam seamlessly, and why the default setting (Routing Mode) isn't the correct configuration for this specific use case.

Routing Mode (Default)

For any new SSID you create in the Plasma Cloud console, Access Points will be configured to use Routing Mode by default. With this setting, configuration of IP addresses, DHCP and Internet access via NAT will be handled in an automated fashion. Routing mode grants a "plug and play" experience with minimal set up procedures. It also ensures your WiFi operates without requiring additional network equipment (such as DHCP servers). 

However, using Routing Mode results in WiFi clients experiencing temporary disruptions when changing connection from one Access Point to the next. Whenever a WiFi client detects a nearby Access Point broadcasting the same network with better signal quality, it may decide to change to the stronger WiFi connection. The DHCP server on the new Access Point will assign another IP address to the WiFi client and this change in IP address may lead to a temporary connection loss. Most affected are applications like VoIP, music & video streaming. 

The graph below shows a WiFi client moving between different APs to better explain this use case. 

As depicted, Access Point handover in Routing Mode results in the assignment of a new client IP address. Due to this IP change, the WiFi client may experience temporary disruptions when using streaming services that require persistent connection. To avoid this issue, you should set up Bridge Mode instead.

Bridge Mode (Best for Roaming)

By nature, Bridge mode requires a central DHCP server to be present in your LAN. This ensures there is only one authority handing out IP addresses to all devices and WiFi clients alike.

Whenever a WiFi client switches to a nearby Access Point and registers itself again, the central DHCP server will recognize the same WiFi client and retain its assigned IP address. Consequently, even sensitive Internet applications such as VoIP calls, music & video streaming continue to function without disruption.

The graph below shows a WiFi client moving between different APs to better explain this use case. 

As depicted, WiFi clients can roam seamlessly when your SSID is set to Bridge Mode. However, please note this set up requires a DHCP server to be present inside the LAN providing an IP address to all WiFi clients. Familiarize yourself with your LAN to identify whether there's a device capable of operating as central LAN DHCP server.

When configuring a DHCP server, please make sure your configured DHCP IP address pool is large enough to accommodate all devices and WiFi clients in your network. Once the IP address pool is exhausted, new WiFi clients are no longer able to connect to your network.