Six stations $($S$1-$S$6)$ are connected to an extended LAN through transparent bridges $($B$1,$ B$2$ and B$3),$ as shown below. Initially, the forwarding tables are empty. Suppose the following stations transmit frames: S$1$ transmits to S$5,$ S$3$ transmits to S$1,$ S$4$ transmits to S$3,$ S$5$ transmits to S$2,$ S$2$ transmits to S$5$ and S$3$ transmits to S$2.$ Explain the steps involved in bridge learning and fill up the forwarding tables with appropriate entries after the frames have been completely transmitted.$($HINT: Port $3$ and Port $6$ are blocked ports$)(2$ marks$)$