This read-write string names the cleartrac unit to use as the next hop for a class's transparent or PVC multiplex traffic when several equal-cost direct links or rack backbone connections are available. It matters operationally because assigning different preferred routes to different classes lets an admin statically load-balance traffic across redundant physical paths instead of letting the system pick arbitrarily. For example, an admin could point a low-priority class's classPrefRoute at 'RACK2-UNIT' so its traffic takes a separate backbone path from the mission-critical class.