Bridges are devices (computer) that can transmit data between two heterogeneous LAN. Bridges divided a large network into smaller segment. They also filter data and keep the traffic separate for each segment.
When a packet enters a bridge, it reads the address contained in the frame and compares that address with a table. When the bridge finds a match, it sends the packet to the destination segment.
A bridge operates in the following manners:
a) It receives all signals from both segment A and B.
b) It reads the address and filters all signals from segment A that are addressed to the segment because they need cross the bridge.
c) Signal from segment A addressed to a computer on segment B are transmitted to segment B.
d)The signals from segment B are treated in a similar way.