How to Configure a Stack of L3 Switches in Controller Mode

Configuration Guide
Updated 05-13-2024 22:12:11 PM FAQ view icon5477
This Article Applies to: 

Applies to Omada SDN Controller v5.13.30.8 and above.

This article will introduce how to configure a stack of L3 switches in controller mode.

What is a stack of switches?

Stack is a device virtualization technology that connects two and above switches supporting stack features via cables through their stack ports, which logically virtualize them to one device as a whole to forward data in the network in Layer 2 and Layer 3 protocols. Through this feature, switches can be stacked to improve reliability, expand port numbers, increase bandwidth, simplify networking, etc.

In Controller mode, there are two methods to stack switches. One is to configure the stacking system in Standalone mode first and then adopt it under the controller; the other is to adopt devices under the controller and then configure the stacking system on the controller. Here, we take the SG6654XHP as an example to introduce these two configuration and adoption methods.

1. Example 1: Adopt switches that have already completed stacking.

According to the given topology, first configure the stacking system in Standalone mode and adopt this system on the controller. To avoid broadcast storms during the configuration process, it is recommended to configure switches first and then physically connect them using copper cables.

1.1 Configure the stack in Standalone mode

Configure Switch1:

1) Configure the stack priority



Switch1(config)#switch 1 priority 100

2) Create stack-groups and add stack ports

Switch1(config)#switch 1 stack-group 1

Switch1(stack-group)#interface 1/0/49

Switch1(stack-group)#interface 1/0/50

Configure Switch2:

1) Configure the stack priority



Switch2(config)#switch 1 priority 50

2) Create stack-groups and add stack ports

Switch2(config)#switch 1 stack-group 1

Switch2(stack-group)#interface 1/0/49

Switch2(stack-group)#interface 1/0/50


Switch2(config)#switch 1 stack-group 2

Switch2(stack-group)#interface 1/0/53

Switch2(stack-group)#interface 1/0/54


1. The stack-group must have at least one stack port. You can increase the bandwidth by increasing the number of stack ports in the stack-group.

2. The stacking ports between different switches must be added to different stack-groups. Therefore, for switch2, ports 1/0/49 and 1/0/50 should be added to stack-group 1 to establish stacking with switch1, while ports 1/0/53 and 1/0/54 should be added to stack-group 2 to establish stacking with switch3.

Configure Switch3:

1) Configure the stack priority



Switch3(config)#switch 1 priority 20

2) Create a stack-group and add stack ports

Switch3(config)#switch 1 stack-group 1

Switch3(stack-group)#interface 1/0/49

Switch3(stack-group)#interface 1/0/50

1.2 connect the stack ports

After the configuration is complete, correctly connect the stack ports using 10 Gbit/s optical modules or 10 Gbit/s copper cables.

In the command output of the show switch, you can see that the state of the three switches is Ready.

By running the show switch stack-ports command, you can see that the status of each stack port is OK.


The default unit-id of the device is 1. After the switch is stacked, the Master assigns a new unit-id. You can see that the unit-id of switch2 and switch3 is changed to 2 and 3, respectively. Therefore, if you need to modify the stacking ports after a successful stacking, it is necessary to base it on the new unit-id and port numbers.

1.3 Connect the controller and adopt the Master of the stack system

Connect the stacking system to the Controller, and at this point, you can see the Master of the stacking system in the device list on the Controller. Click the Adopt button to adopt this device (since the username and password have been modified, the first attempt to adopt may fail. Click Retry and enter the correct username and password to adopt successfully).

1.4 Scan and adopt members of the stack system

After adopting the master, on the Devices-Device Group-Stack Group page, click the scan button on the right.

You can see the member of the Stack system, check it, and click Add to Stack Group.

Click the plus sign in front of the stack group to expand and view the status of all stack members.

Click the Edit button on the right of the stack group to perform other configurations on the stack group, such as modifying the Stack name, adding new stack members, and removing stack members.

On the Devices-Device group-stack group page, click Stack Group. The private configuration page is displayed on the right.

2. Adopt switches before configuring stacking

Similarly, we plan to adopt and configure a stack system with the following topology (denoted as topology 1) on the controller.

To avoid problems such as broadcast storms and network interruption during the configuration process, the stack port must be in the linkdown state during controller stack configuration. Therefore, connect the three switches using non-stack ports first, such as the following topology (referred to as topology 2) :

2.1 Controller adopts three switches

In Devices->Device List, adopt the three switches waiting to be stacked.

2.2 Configuration stack

On the Devices->Device group-Stack Group page, click Create New Stack

Set Stack Name, select three switches and configure UNIT-IDStack Priority, and stack-group as planned. The configuration of the above topology is shown in the following figure. Click add.

Note: After clicking Add, the switches with changed unit-id will automatically restart, such as switch2 and switch3 in this example.

Click the port to select the stack-group id to join.

After switch2 and switch3 are restarted, disconnect the cables between switch1 and switch2 and between switch2 and switch3 in topology 2, and connect the stacking ports using 10G optical modules or 10G copper cables based on topology 1. After the Stack is complete, check the stack status, modify the stack configuration, and configure the stack system privately on the Devices-Device group-stack Group page. For details, see Step 4 in Example 1.

For detailed descriptions of stack, unit-id, stack-priority, stack-group, etc., see CLI Guide and User Guide.

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