MAC address learning

In an SPBM network, BEBs perform typical source MAC learning in the data plane to learn C-MACs, but BCBs do not learn C-MACs.

BCBs forward MAC-in-MAC traffic by destination B-MAC and B-VLAN, which are advertised through ISIS-SPB in the control plane. As a result, BCBs do not need to maintain a large MAC address table.