This read-write TruthValue indicates whether Variable Bit Rate traffic can be routed over the trunk; if True it can be rerouted, otherwise it cannot. An administrator uses it to permit or exclude bursty VBR connections from a given trunk, since VBR's traffic envelope behaves differently from constant-rate or best-effort classes. For example, an admin might disable Vbr on a trunk that is already near capacity from CBR traffic to avoid bursts causing cell loss.