The MAC address learning mechanism is as follows:
1. For traffic between physical interfaces, a MAC address learned by a physical interface is valid only to the local board. If traffic flows out through a physical interface, the local board learns EMAC addresses and does not synchronize the learned addresses to other boards in the subrack.
2. If traffic flows out through a trunk, the learned MAC addresses are synchronized to the other boards on the subrack.
1. If a user with the MAC address 1122-3344-5566 under GigabitEthernet 1/1/1.1 accesses GigabitEthernet 2/0/6, board 2 learns the MAC address 1122-3344-5566.2. If a user with the MAC address 1122-3344-5566 under eth-trunk1.1 (on board 1) accesses eth-trunk2.2 (on board 2), board 2 learns the MAC address 1122-3344-5566 and synchronizes the MAC address to other boards in the subrack.