Port range and QoS settings for proxy based recording

Owned by Kiss, Mate
May 24, 2022
1 min read

Media port range

Verba Proxy Servers use a predefined UDP port range for media relaying. These ports are not constantly open for listening as they are allocated on-demand as the relay service needs them. The number of ports required to relay a call depends on a number of factors:

  • Every established voice call requires minimum 4 ports (2 RTP, 2 RTCP).
  • Every established video call requires minimum 8 ports (4 RTP, 4 RTCP).
  • During call setup, endpoints use additional ports during ICE negotiation. These ports are only allocated for a few seconds.
    • If an endpoint has 1 wired and 1 wireless connection, it will requires 2x4=8 ports on the relay server during call setup and ICE negotiation (first ~10sec).
    • For RGS and simulring call scenarios, Lync tries to allocate ports for each and every possible endpoint (RGS members, targets). If a team has 20 members, the system will try to allocate 20x4 ports at once during call setup and ICE negotiation (first ~10sec).

If the media port range is not configured properly, and the there is not enough port available, the call setup will fail.

QoS configuration

The Verba Proxy Servers are subject to Quality of Service (QoS) design as the media streams will go through these servers. More information on QoS design in Lync: https://technet.microsoft.com/en-us/library/gg405409.aspx

If you want to apply QoS policies, follow the guidelines of this article: https://technet.microsoft.com/en-us/library/jj204681.aspx. It is about the internal interface of the Edge Server, which is identical to the Verba relay server concept. The port range defined in the QoS policy must match the range configured for the proxy server.