Intelligence must be very near the source to quickly detect and adapt to resources and demands. In addition, bandwidth usage and characteristics must be monitored and reported to avoid surprises and user dissatisfaction. Voice uses relatively small amounts of bandwidth, but is very sensitive to delay and somewhat sensitive to packet loss. Data requires higher amounts of bandwidth for short periods of time and is delay-sensitive because a person is awaiting a response. Packet loss, as long as the severity does not impact the transaction's responsiveness, is of less concern because retransmission will ensure accurate delivery.
Video requires much more bandwidth and is sensitive to both delay and packet loss.
These three applications have varying requirements for bandwidth capacity, delay, delay variation, and packet loss that are specific to the user and situation. Each user has different levels of tolerance and may need different policies defined and enforced. With a packet-based infrastructure, network capacity can increase faster. The greater flexibility of packet-based services allows customers to receive service levels appropriate for their application, time and business requirements. Convergence to the packet infrastructure will occur as applications are written to its advantage.