Hierarchical Quality of Service (HQoS) is a technology that uses a queue scheduling mechanism to guarantee the bandwidth of multiple services of multiple users in the DiffServ model.
Traditional QoS performs 1-level traffic scheduling. The device can distinguish services on an interface but cannot identify users. Packets of the same priority are placed into the same queue on an interface and compete for the same queue resources. HQoS uses multi-level scheduling to distinguish user-specific or service-specific traffic and provide differentiated bandwidth management.