The Bandwidth Balancing (BWB_DQDB) and Guaranteed Bandwidth (GBW_DQDB) mechanisms have been recently proposed for addressing the issue of channel bandwidth allocation on DQDB type networks. BWB_DQDB can introduce fairness into a DQDB network while GBW_DQDB can guarantee the bandwidth of certain high priority stations. In this paper, we introduce the Guaranteed Bandwidth and Balancing mechanism (GBWB_DQDB) which aims at combining the advantages of BWB_DQDB and GBW_DQDB. That is, it can guarantee the bandwidth of high priority stations and, at the same time, enables them to compete for the remaining channel bandwidth. We provide a detailed description of the new mechanism and investigate its performance through simulation results. Furthermore, we compare GBWB_DQDB with BWB_DQDB and GBW_DQDB.