Protocols, performance, and controls for voice over wide area packet networks

We propose and compare alternative protocols, architectures, and controls for providing long distance (LD) voice services over asynchronous transfer mode (ATM) and Internet protocol (IP)-based networks. ATM standards and products are already mature enough for high-quality voice transport over a multiservice network infrastructure. The main design choices we must make are related to voice processing at the synchronous transfer mode (STM)-ATM interface, signaling protocols, and appropriate use of permanent virtual circuits (PVCs) and switched virtual circuits (SVCs). We compare the various alternatives along these dimensions. High-quality LD voice service over IP backbones is still a challenge. We propose different alternatives for providing such a service over a managed, multiservice IP network. First we consider a simple architecture involving line-speed forwarding, priority scheduling for voice over data, connection admission controls (at signaling gateways), and virtual provisioning servers. We then enhance the simple architecture to add hierarchical bandwidth guarantees, scheduling, and buffer management made available by emerging Layer 3/Layer 4 IP switches. We show that the basic and enhanced architectures allow integration of LD voice service with the best-effort service and multiservice virtual private networks (VPNs), respectively.