Configuring Pexip Infinity to use a STUN server

A STUN server allows clients, such as Conferencing Nodes, to find out their public NAT address. In Microsoft Lync and Skype for Business deployments it is essential that a Conferencing Node can discover its public NAT address.

By default, Conferencing Nodes will send their STUN requests to the TURN server, but if the TURN server is not located outside of the enterprise firewall — the Conferencing Node will not be able to discover its public NAT address. If this is the case in your deployment scenario, you must configure a separate STUN server. The Conferencing Node's STUN requests will then be sent to the STUN server, instead of the TURN server.

You do not need to configure STUN servers if the STUN requests sent from the Conferencing Nodes to the TURN server will return the public NAT address of the Conferencing Node.

To configure STUN servers, you must be running Pexip Infinity version 9 or later software.

How Conferencing Nodes decide which STUN server to use

The STUN server used by a Pexip Infinity Conferencing Node handling a call is determined as follows:

• Conferences: uses the STUN server associated with the location of the Conferencing Node that is handling the call signaling.
• Point-to-point calls via the Pexip Distributed Gateway: uses the STUN server associated with the Gateway Routing Rule that matched the call request. If there is no STUN server associated with the rule, then the STUN server associated with the location of the Conferencing Node that is handling the call signaling is used instead. Note that rules can optionally be configured on a per-location basis.

If a STUN server is not configured for a location or rule, but a TURN server is configured, the Conferencing Node will send STUN requests to that TURN server.

Nominating the STUN servers used by Pexip Infinity

Within Pexip Infinity you can configure the addresses of one or more STUN servers. You then associate those STUN servers with each System location and with each Gateway Routing Rule.

Configuring STUN server addresses

To add, edit or delete STUN server connection details, go to Call control > STUN servers. The options are:

Option	Description
Name	The name used to refer to this STUN server in the Pexip Infinity Administrator interface.
Description	An optional description of the STUN server.
Address	The IP address or hostname of the STUN server. This should not be the same address as any of your configured TURN servers.
Port	The IP port on the STUN server to which the Conferencing Node will connect. Default: 3478.

Note that Pexip Infinity ships with one STUN server address already configured by default: stun.l.google.com. This STUN server is typically used by Infinity Connect WebRTC clients and uses port 19302 (rather than the common 3478).

You can use this STUN server or configure a different one.

Associating STUN server addresses with Conferencing Nodes

To associate a STUN server address with a Conferencing Node, you must configure the node's system location:

1. Go to Platform configuration > Locations.
2. Select the Conferencing Node's location.
3. Select a STUN server and select Save.

All Conferencing Nodes in that location will use the nominated STUN server for conference calls.

Client STUN servers

Note that the per-location Client STUN servers option is used to configure the specific STUN server addresses that are provisioned to Infinity Connect WebRTC clients. These STUN servers are used by the WebRTC client to discover its public NAT address.

Associating STUN server addresses with gateway calls

If a gateway call is being placed to an ICE-enabled client (such as Lync / Skype for Business clients and Infinity Connect WebRTC clients), the Conferencing Node placing the call will use the STUN server associated with the matching rule. (For gateway calls, the Conferencing Node does not use the STUN sever associated with its system location.)

To associate a STUN server address with a Gateway Routing Rule:

1. Go to Service configuration > Distributed Gateway.
2. Select the relevant rule.
3. Select a STUN server and select Save.