Call admission control: QoS issue for VoIP

—One of the vital key elements for providing Quality of Service (QoS) for VoIP is the Call Admission Control (CAC) capabilities of the Session Management /Call Session Control Function or gateway. Even though the network may be designed to meet a given performance and restoration objective for the engineered traffic loads, the actual traffic may be significantly higher. Without a CAC function in a VoIP network during overloads, links become congested and new calls keep getting admitted. All calls in progress, not just the new calls start dropping packets and experiencing longer delays. Contrast this to a circuit switched network, where new calls get blocked, but calls in progress experience good call quality. In the VoIP case, packet loss could become large enough that calls become unintelligible, callers hang-up their call, and most will reattempt. This paper gives an overview of potential CAC approaches, highlighting four basic alternatives; based on endpoint performance measuremen...

• Type: Conference
• Year: 2008
• Where: COMSWARE
• Authors: Mohammad Asadul Hoque, Farhana Afroz
• Keywords: Admission Control, Bandwidth Management, Call Admission Control, COMSWARE 2008, Software Engineering