This chapter assessed the need for QoS and the implications for the enterprise when you use an MPLS VPN-based service. The conclusion is that the need for QoS is real in the LAN, WAN, and SP transit network in support of the move toward a converged network. You must understand the mechanisms that are available to solve the application of QoS in the network, how to take a rational and staged approach toward developing a scalable policy, and how to execute that policy.
QoS is not a silver bullet that creates bandwidth. It needs to be used as part of a well-defined capacity planning and overall application governance process that identifies current and future state evolutions. Ensuring that the network can support the enterprise developments in a productive and manageable form should be the aim of any policy development so that it remains manageable over time.
The common theme is planning, designing, implementing, and operating. Build on these themes to ensure that there is consistency in the QoS strategy from an end-to-end architecture perspective. As this technology evolves, there will be additional areas to explore, especially call admission control and resource reservation. Indeed, the recent implementation of "MLPP for Voice and Video in the Internet Protocol Suite," currently in the IETF Draft stage by F. Baker, et al., shows promise as to developing the right answers.
To more fully explore the vast topic of QoS, it is highly recommended that you read the Cisco Press book End-to-End QoS Network Design: Quality of Service in LANs, WANs, and VPNs by Tim Szigeti and Christina Hattingh.