Abstract: Methods for quickly determining loss of synchronization and for quickly reestablishing synchronization of a sub-aggregate frame having primary and secondary frames and contained within an independently synchronized aggregate are provided. In determining loss of synchronization, synch bits are located in the secondary frame such that when the composite subaggregate frame is synchronized the synch bits are chosen to be inserted into the same predetermined position in the aggregate. The synch bits are provided with values such that a collection of synch bits of a composite frame provides an internally non-repeating pattern. By comparing bit values received in the predetermined location of the aggregate at the synch bit rate with the non-repeating pattern, a determination is made as to whether synchronization has been lost.