<P> A simple bridge connects two network segments, typically by operating transparently and deciding on a frame - by - frame basis whether or not to forward from one network to the other . A store and forward technique is typically used so, during forwarding, the frame integrity is verified on the source network and CSMA / CD delays are accommodated on the destination network . Contrary to repeaters that simply extend the maximum span of a segment, bridges only forward frames that are required to cross the bridge . Additionally, bridges reduce collisions by partitioning the collision domain . </P> <P> A multiport bridge connects multiple networks and operates transparently to decide on a frame - by - frame basis whether and where to forward traffic . Like the simple bridge, a multiport bridge typically uses store and forward operation . The multiport bridge function serves as the basis for network switches . </P> <P> A transparent bridge uses a forwarding database to send frames across network segments . The forwarding database starts empty - entries in the database are built as the bridge receives frames . If an address entry is not found in the forwarding database, the frame is flooded to all other ports of the bridge, flooding the frame to all segments except the one from which it was received . By means of these flooded frames, the destination network will respond and a forwarding database entry will be created . </P> <P> In the context of a two - port bridge, one can think of the forwarding database as a filtering database . A bridge reads a frame's destination address and decides to either forward or filter . If the bridge determines that the destination node is on another segment on the network, it forwards (retransmits) the frame to that segment . If the destination address belongs to the same segment as the source address, the bridge filters (discards) the frame . As nodes transmit data through the bridge, the bridge establishes a filtering database of known MAC addresses and their locations on the network . The bridge uses its filtering database to determine whether a frame should be forwarded or filtered . </P>

The point of entry from a wireless device to a wired network is performed at a device called a