Given the following MPLS L2 configuration command:
mpls-relay 10.1.1.1 4
Which two statements true? （）(Choose two.)

A. This command is applied to the core router facing interface.
B. This command is applied to the customer facing interface.
C. The 4 is locally significant and identifies the layer 2 circuit.
D. The 4 must match exactly on the peer router configuration on the remote end.