What does Class-Based Queuing (CBQ) mean?
Class-based queuing (CBQ) describes a system where network administrators assign a specific priority to each transmission or set of data packets, depending on what type of transmission it is. Network schedulers and other tools allow different types of data through traffic to share system bandwidth. In class-based queuing, administrators create classes to prioritize what gets done most quickly.
Techopedia explains Class-Based Queuing (CBQ)
Another way to think about this is implied in Gartner's definition of class-based queuing where the process “divides traffic into queues and assigns each a specific amount of network bandwidth” — in other words, there's a certain amount of resources applied to each type of item, and that defines how quickly it is processed.
What are the criteria for prioritization in class-based queuing? Criteria can include the type of interface used, the originating program, the IP address of the sender, the type of application being served, and other factors. In general, class-based queuing works to limit or restrict resource processing in systems in order to, again, prioritize and allocate resources in specific ways.