SPRUIU1C July 2020 – February 2024 DRA821U , DRA821U-Q1
The 2-port switch has a host port, and that port can operate in two fundamental modes. Bridge mode allows the host to extent the switched domain to another network like Wi-Fi or another multi-port switch. In this case the host must be able to see unknown unicast addresses so they can be broadcast to the other network. In Port mode the host need not see any unknown unicast traffic. The CPSW_ALE_CONTROL[8] EN_HOST_UNI_FLOOD bit determines the host mode for unknown unicast traffic. This bit should only be set if you are bridging two or more networks together.
Essentially the two port switch is a MAC with all the switching features like VLAN insertion, removal, update, etc.
The 2-port switch would normally have a very small ALE table. Its primary use is for the Host filtering features. For example you would not ever need to auto learn or add addresses of external nodes to the ALE table, the tables primary purpose is to host unicast addresses, multicast addresses, VLANs, IP addresses etc.