The Designated Forwarder (DF) for a given VLAN/BD is the MCT node responsible for forwarding BUM traffic received in the flooding domain. This method is used for VxLAN tunnel clients and PW clients. The DF election is made per client and per VLAN/BD.
When the client state is up on both MCT peers, one MCT node becomes DF for all odd-numbered VLANs/BDs and the other becomes DF for all even-numbered VLANs/BDs. For a PW client, this is run globally, whereas for VxLAN clients this is run per VxLAN tunnel.
If the VxLAN tunnel client is down on one side, the corresponding tunnel on the peer node becomes the DF for all VLANs/BDs extended on it.