Chapter 3 Featured Functions Then the traffic between Bridge B and C will flow through Bridge A. But STP/RSTP can’t support more VLANs in your network topology. If there are 2 VLANs between 2 bridges, one path will be blocked when STP/RSTP is enabled. So IEEE defined an extension to RSTP to further develop the usefulness of VLANs. 3-43