 assuming there are no physical-layer problems, you probably need more bandwidth. If you're running VoIP over a T1, and the calls are choppy, adding more band- width may not solve your problem because the problem probably isn't simply a matter of bandwidth. The key here again is congestion. If you've got choppy calls, and your links aren't congested, you need QoS to prioritize those voice packets SO they get delivered first. QoS prevents packets from being dropped If you've got a problem with excessive packet drops, QoS will not solve it. What QoS will do for you is help you get the important packets through SO that only the less important packets get dropped. Traffic shaping can prevent packets from being dropped (assuming buffers are not similarly saturated), though this is not really suitable for voice or video. Additionally, traffic shaping only buffers packets to a point, SO if you're oversub- scribing your link all day long, traffic shaping won't help you. QoS will make you more attractive to the opposite sex Sad to say, I'm afraid this isn't true either, though in theory, it is possible that your dream date could be reading this very book right now! Common QoS Misconceptions CHAPTER 30 Designing a QoS Scheme Designing a QoS scheme can be a relatively simple task, or a very large project. The scale of the solution depends on the complexity of your network, and the needs of your business. As a general rule, I like to plan everything I do with an end state design in mind. Even if I'm implementing a QoS scheme for a company that cur- rently doesn't have VoIP, I'll design a scheme that assumes VoIP is coming in the future. In this chapter, I'll walk you through designing a QoS scheme for a network that will require VoIP. Designing QoS is a two-part process: first, you must determine the requirements for the system, and then you have to configure the routers. We'll use low-latency queuing (LLQ), which is the recommended solution according to Cisco. Determining Requirements The first part of the QoS design proces