Traffic demands in the Internet today include delay-sensitive traffic that require better than the standard "best effort" service provided by IP networks. As a result, various new technologies and mechanisms to support all types of traffic with various performance requirements are being developed and implemented. The traditional methods for capacity planning of IP networks are limited in that they only consider "best effort" service, or else a single delay constraint for all traffic. In this paper, we propose a framework for capacity planning tool that takes into account the new technologies that can provide QoS and allow for multiple delay constraints so that guaranteed performance can be achieved for each of the traffic classes. To provide a foundation for the capacity planning procedure, we first overview and categorize the QoS mechanisms deployed in IP-based networks and identify their implications for network planning. We then describe some specific features and algorithms that have been incorporated into the capacity planning tool for multiservice IP networks.