Fair Queuing is similar to CBQ in that it queues packets in the same way but it attempts to be more intelligent by being based on relative allocations rather than priorities. It is always based on traffic "flows" which do not always give you what you want. For example if you are trying to allocate bandwidth to a user or customer flows are only a subset of what you wish to allocate fair bandwidth to.

Also, like CBQ, Fair Queuing works well in environments where there are a small number of users and a small number of definable flows. When the number of manageable queues gets large then it is no longer beneficial to manage the available bandwidth fairly between all the flows.