Routers vs. Bridges

Efficiency - Routers are far more efficient than Bridges because:

• Bridges learn where packets should go by using a broadcast or "flooding" method. In effect, a bridge says, "I'm not sure where to send this information, so I will send it everywhere."
• Routers on the other hand make intelligent decisions about sending a packet across the network by examining the source and destination address of each packet, forwarding only those packets destined for a remote network. So rather than blindly broadcasting to the entire network, the router efficiently routes the packets to their destination. This eliminates unnecessary traffic and makes better use of bandwidth.
• Even worse, each bridge is obligated to forward every broadcast from every other segment in the network, dramatically increasing the broadcast rate. For example, in a two-segment network, broadcasts from one side must be forwarded by the bridge to the other side, doubling the broadcast rate of a single-segment network. Adding a third segment and second bridge increases the broadcast rate three-fold. Such broadcasts consume valuable CPU power on every host connected to the network.
• In larger networks, bridging architectures lead to tremendous network overhead related to address resolution, naming resolution and device location.
• Bridging is a particularly poor architectural choice because the bridge must constantly relearn the network when additions or changes are made.