This read-write Integer32 reports the number of received packets on this MP link that are currently waiting to be reordered, per its source description. An admin monitors this to see how much reorder-queue backlog exists on the multilink bundle at any given moment, which can signal buffering pressure from channel jitter. For example, a persistently nonzero or climbing value here would prompt the admin to check whether one member channel of the bundle is lagging the others.