A network element includes a backplane, which includes a backplane memory holding first medium access control (MAC) address values. The network element further includes multiple tributary modules coupled to the backplane, which include network interfaces that are configured to communicate over network trunks using MAC addresses that are respectively assigned to the network interfaces. The network element further includes a common function module (CFM), which communicates with the tributary modules and the backplane memory via the backplane, and which includes a CFM memory holding second MAC address values.The CFM is arranged to assign the MAC addresses to the network interfaces by selecting the MAC addresses from among the first MAC address values when the CFM is able to access the backplane memory, and by selecting the MAC addresses from among the second MAC address values when the CFM is unable to access the backplane memory.