03-02-2015 01:21 AM
Voice and video devices use a signaling protocol to establish, control, and terminate voice and video calls. These control or signaling sessions are usually permitted using pre-defined ACLs. If, however, the control signaling packets are encrypted, the controller cannot determine which dynamic ports are used for voice or video traffic. In these cases, the controller has to use an ACL with the classify-media option enabled to identify the voice or video flow based on a deep packet inspection and analysis of the actual traffic.