The role of bridge

Learning: Site A transmits data to B, the bridge frame source address learned A viewing port 1 was added, filtered database <A, 1>.

Diffusion: B bridge does not know where the frame thus diffused to all other ports (i.e., ports 2 and 3).

Forwarding: B A received frame sent, then, might respond, i.e., the transmission data B to A, this time to inspect the bridge B in the source address learned on the port 2, the entry is added <B, 2>, while the frame a destination address in the

filtering

database is present, and in the port 1, and therefore B back to the port forwards the frame a 1

filter: a now transmits data to the station C, since a, C, and a bridge connected to the same hub , the bridge will also receive the frame, source address look C, recorded at port 1 C, was added entries <C, 1>, while the destination address in the a

port where the filter database and the frame is received port, so do not be forwarded.

Have increased filtering database entries TTL per second, more than a certain value from the database purge, general default TTL is set to 300 seconds: Aging. Aging mainly on account of the limited memory of the bridge, in the case of mobile nodes.

Periodically clear, the same as the timer
 
switched: https://blog.csdn.net/mariofei/article/details/23298603