In this paper, we consider interconnection of IEEE 802.15.4 beacon enabled network clusters using ordinary network nodes as bridge nodes. Bridge design involves uplink transmission to the coordinator and downlink transmission to the bridge. The bridge periodically visits source and sink cluster and exchanges data using slotted CSMA-CA access. We develop an algorithm for inter-cluster communication and evaluate its performance for the array of three interconnected clusters. We indicate the range of traffic intensity where this design solution is operational.