The switch aligns the SPB ethertype to BCB's locally configured SPB ethertype. The BCBs mark the BTAG Ethertype of a transit MAC-in-MAC packet to match its locally configured value when it exits on a different network-to-network interface (NNI) port, even if the BTAG Ethertype on the incoming packet (CFM or SPB) does not match its configured value.
Note
IS-IS Hello packets are always marked with 0x8100 ethertype, and do not change according to the BCB's locally configured values.