H3C S5120-SI Series Command Reference Manual page 384

Use the undo port multicast-vlan command to restore the system default.
By default, a port does not belong to any multicast VLAN.
Note that a port can belong to only one multicast VLAN.
Examples
# Assign GigabitEthernet 1/0/1 to multicast VLAN 100.
<Sysname> system-view
[Sysname] interface gigabitethernet 1/0/1
[Sysname-Gigabitethernet1/0/1] port multicast-vlan 100
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