Class of Service (CoS) is the correct mechanism for categorizing and managing traffic by assigning a priority level to packets. This is particularly useful in a scenario where specific traffic types, such as VoIP, need prioritization over others like HTTP to maintain quality. Traffic shaping, although it manages bandwidth, does so by controlling the rate of traffic sent into the network, which isn't specifically about prioritization of different traffic types. Packet sniffing is a method used for monitoring network traffic and is not related to managing traffic priority. Load balancing distributes traffic across multiple servers or links but doesn't prioritize traffic types.