Final answer:
The function of learning network addresses and converting frame formats is performed by a bridge, which operates at the data link layer of the OSI model and filters or forwards traffic based on learned MAC addresses.
Step-by-step explanation:
The function of learning network addresses and converting frame formats is primarily associated with a bridge. A bridge is a network device that connects two or more network segments. It works at the data link layer of the OSI model, which means it can filter, forward, or flood the traffic based on the MAC addresses it learns. By learning the MAC addresses of the devices on each segment, the bridge can determine which frames are to be forwarded and which are to be filtered.
In contrast, a switch operates at a similar level but usually has more ports and features. It also learns MAC addresses but can handle much more traffic because of its capability to create multiple simultaneous communication channels. A hub, on the other hand, is a simpler device that does not learn addresses; it simply repeats the signals it receives to all other ports, leading to potential network collisions. An MAU (Media Attachment Unit) typically refers to a component that connects a workstation to a network in environments like Token Ring networks and is not directly related to frame conversion or network address learning.