If a class in Class Based Weighted Fair Queueing (CBWFQ) is not using its bandwidth, can other classes use the bandwidth?
A. Yes. Although the bandwidth guarantees provided by issuing the bandwidth and priority commands have been described with words like “reserved” and “bandwidth to be set aside”, neither command implements a true reservation. Meaning, if a traffic class is not using its configured bandwidth, any unused bandwidth is shared among the other classes. The queueing system imposes an important exception to this rule with a priority class. As noted above, the offered load of a priority class is metered by a traffic policer. During congestion conditions, a priority class cannot use any excess bandwidth. For more information, refer to Comparing the bandwidth and priority Commands of a QoS Service Policy.
