With the increase of mobile devices running 3CXPhone on iOS, Android or Windows PCs the importance of a fast and reliable wireless infrastructure becomes more and more a key point within networks. Even more the handover from one access point to the next while beeing in a call (also known as roaming) brings more challenges as the ARP cache of switches needs to learn as fast as possible the new network port (access point) where the IP device has roamed from and to, in order to be able to send the RTP traffic (audio) to the new access point.
While roaming is very well integrated within DECT systems and evolved over the years, the limitation that DECT can only be used for calls has remained ever since. This makes the purchase of this technology very costly as it can not be leveraged and can be easily compared with the separate telephone wiring used in proprietary telephone systems.
In order to recreate the seamless roaming capabilities in wifi networks a centralized controller for the APs (Access Points) is needed as single APs will not be able to update the ARP (Address resolution Protocol) inside networks as quickly as needed. If only one AP is needed to cover the office the rest of the document is not applicable as no roaming is performed.
The Ruckus Zonedirector is one of the many wifi central management solutions which offer a central point of configuration for all APs within your network. Even more it features a special option for VoIP where the traffic is routed from all APs to the Zone director’s network port rather than to the network port of the AP itself. With this “trick” when roaming from one AP to the next the ARP cache for the IP/MAC of the wireless device on the switch will not change and this enables seamless roaming for the wireless IP device while beeing in a call across the infrastructure.
Configuring a WiFi for VoIP traffic
By not going into detail on the basic setup of a Ruckus Wireless System here are the main settings which should be set to enabled VoIP traffic handling for roaming.
Centralize the Output Port to the ZoneDirector
Open the Ruckus Wireless ZoneDirector and navigate to “Configure -> WLANs -> WLANs” and click on Edit for the WiFi network in question. You may also create just a Wlan for VoIP and leave the default network – which may be used for pure data transmission – untouched.
- Set the Priority of the WiFi to High in order to decrease the latency in very busy networks which will benefit in VoIP to keep the Jitter Buffer as low as possible.
- Enable the Tunnel Mode which will force all APs joined to this Wifi-Group not to output the data directly to the switch port of the AP itself, but to send it to the ZoneDirector which then will become the single network output point for Voice Calls
By default the Ruckus network will convert Multicast messages to a Unicast message when less than 5 participants are detected in the network to receive this information. As 3CX Phone System only receives Multicast a reconfiguration is needed in order to not convert Multicast to Unicast. Note, this step is only needed when VLan Tagging is enabled for WiFi.
Log in to the Zonedirector via Putty with the credentials used to log in to the web interface.
- Switch into configuration mode by entering “en” followed by “configure”
- Select the WiFi name (SSID) to be configured for Multicast Conversion
- e.g. “wlan iStefan”
- Disable the conversion by entering “no qos directed-multicast”
- save the configuration with “end”
- You may now disconnect from the ssh session
After the reconfiguration Android, iOS and Windows PCs can be configured via PnP as the Bold entry message shows up on the Phone node within the 3CX Management Console.