H3C S5120-SI Series Command Reference Manual page 112

Related commands: mirroring-group.
Examples
# Configure GigabitEthernet 1/0/1 as the monitor port in local mirroring group numbered 1.
<Sysname> system-view
[Sysname] mirroring-group 1 local
[Sysname] interface gigabitethernet 1/0/1
[Sysname-GigabitEthernet1/0/1] monitor-port
1-6