Huawei S6720/S5720 series don’t use a dedicated stack module, so you have to select 2 available port on fiber module 10G/1G.
As the image below, we choose the port Xgiga0/0/2 and Xgiga0/0/4 as stacks ports. After the config was done the 2 ports aren’t available for active traffic.

It is needed to adapt the stack config on each unity
- Configure interface
interface stack-port 0/1
port interface XGigabitEthernet1/0/2 enable
interface stack-port 0/2
port interface XGigabitEthernet1/0/4 enable
2. Configure stack master priority, necessary for mantaining a correct slot number if one unity will be out of service
stack slot 0 priority 200
one vlan is dedicated to stack traffic and don’t participate in spanning tree process
a stack config isn’t displayed in running-config
DISPLAY STACK CONFIG
display stack configuration
---------------Configuration on slot 1 Begin---------------
stack enable
stack slot 0 priority 200
stack reserved-vlan 4093
stack timer mac-address switch-delay 10
interface stack-port 1/1
port interface XGigabitEthernet1/0/2 enable
interface stack-port 1/2
port interface XGigabitEthernet1/0/4 enable
---------------Configuration on slot 1 End-----------------
DECONFIGURE INTERFACE FROM STACK
interface stack-port 0/1
shutdown port interface XGigabitEthernet1/0/2
undo port interface XGigabitEthernet1/0/2