How to enable Call Admission Control to Lync/ Skype for Business pool?
First let’s understand why we need Call Admission Control (CAC)?
For IP-based applications such as telephony, video, and application sharing, the available bandwidth of enterprise networks is not generally considered to be a limiting factor within LAN environments. However, on WAN links that interconnect sites, network bandwidth can be limited.
When network traffic oversubscribes a WAN link, current mechanisms such as queuing, buffering, and packet dropping are used to resolve the congestion. The extra traffic is typically delayed until the network congestion eases or, if necessary, the traffic is dropped. For conventional data traffic in such situations, the receiving client can recover. However, for real-time traffic such as unified communications, network congestion cannot be resolved in this manner, because the unified communications traffic is sensitive to both latency and packet loss. Congestion on the WAN can result in a poor Quality of Experience (QoE) for users. For real-time traffic in congested conditions, it is actually better to deny calls than to provide connections with poor quality.
Call admission control (CAC) determines whether there is sufficient network bandwidth to establish a real-time session of acceptable quality. In Skype for Business (Lync) Server, CAC controls real-time traffic only for audio and video, but it does not affect data traffic. If the default WAN path does not have the required bandwidth, CAC can attempt to route the call through an Internet path or the public switched telephone network (PSTN).
You can refer the article to plan Call Admission Control
How to enable Call Admission Control?
Log on to Front End and download Topology Builder > Open topology builder > expand the site which you need to enable for CAC.
Right click on Site name > right click and click Edit properties > Check mark ‘Enable Call Admission Control’ and select appropriate pool name.
How to change Call Admission Control pool server?
Sometime you may need to move CAC server to different pool server. You can easily do the same using below steps:
1. Open Topology Builder.
2. Right-click the site node, and then click Edit Properties.
3. Under Call Admission Control setting, make sure Enable Call Admission Control is selected.
4. Under Front End pool to run call admission control (CAC), select the Lync Server 2013 pool that is to host CAC, and then click OK.
5. Make sure to Publish the topology.
6. Now you need to re-run setup file to all Front End Server from new pool and old pool because you need to remove ‘Lync Server Bandwidth Policy Service (Authentication)’ and ‘Lync Server Bandwidth Policy Service (Core)’ services from old pool Front End server and install same services on new Pool Front End servers.
You can easily do this running bootstrapper.exe on each Front End server. (C:\Program Files\Microsoft Lync Server 2013\Deployment\bootstrapper.exe)
While removing Policy Decision Point component (PDP):
Lync Server 2010
Lync Server 2013
Skype for Business 2015