Abstract: Provided are a network scheduler and a network scheduling method capable of effectively managing network bandwidths by selectively supporting a work conserving mode to network entities by using an improved token bucket scheme. The network scheduler selectively supports a work conserving mode to network scheduling units (NSUs) serving as network entities by using a token bucket scheme, such that the network scheduler ensures an allocated network bandwidth or enables the NSUs to use a remaining bandwidth. The network scheduler manages the NSUs by classifying the NSUs into a green state, a red state, a yellow state, and a black state according to a token value, a selection/non-selection of the work conserving mode, and an existence/non-existence of the packet request to be processed.