What do bridges require that hubs and repeaters do not?

Bridges require address tables, which are essential for their operation in a network. Unlike hubs and repeaters that simply regenerate and transmit signals without any intelligent filtering, bridges actively analyze the data packets being transmitted and determine whether to forward or filter them based on the destination address.

The purpose of an address table in a bridge is to keep track of the MAC addresses of devices on the network segments it connects. When a bridge receives a data frame, it looks up the destination MAC address in its address table. If the address is found, the bridge knows which specific port to forward the frame to, preventing unnecessary traffic in other segments. This feature enhances network efficiency and reduces collisions by directing traffic only where it needs to go.

In contrast, hubs and repeaters operate at a lower level of the OSI model (physical layer) and do not make decisions based on the data's content or addresses. They are incapable of maintaining an address table; their primary function is merely to amplify and distribute the signals they receive. This fundamental difference in function and capability highlights why bridges necessitate the use of address tables, whereas hubs and repeaters do not.