Bridge is the network device which connects multiple segments on the network. Bridge works at data link layer have the ability to read the frame generated from source designated for the destination. Frame is the protocol data unit on data link layer, bridge take forwarding decision by extracting destination address from the frame and look for the match in bridge database.
When the frame arrives on the incoming interface of the bridge, it reads the header for the destination MAC address look in the bridge database for the match, if found frame is forwarded to the destination otherwise frame is broadcast on all the bridge port excluding the source port on which frame arrived. Broadcast frame is verified by all the host if host MAC address and frame MAC address are same, then specific host will respond to the bridge, port is identified and finally bridge will keep the MAC address in the bridge database for future forwarding decision.
· Bridge reduces collusions in the network.
· Bridge separate one segment traffic from other.
· Bridges filter the packets.
· Transparent to protocol above the MAC layer
· Self configuring
· Bridges are more expensive then repeaters
· Bridge causes buffering delays.
· Switch look every frame for MAC results delay
· Bridge consists of one broadcast domain.
· Bridge has less number of ports.
· Does not scale very large networks