  We derive the maximum entropy of a flow (information utility) which conforms
to traffic constraints imposed by a generalized token bucket regulator, by
taking into account the covert information present in the randomness of packet
lengths. Under equality constraints of aggregate tokens and aggregate bucket
depth, a generalized token bucket regulator can achieve higher information
utility than a standard token bucket regulator. The optimal generalized token
bucket regulator has a near-uniform bucket depth sequence and a decreasing
token increment sequence.
