If you need additional ports on your network, switch stacking offers a cost-effective option. This widely used approach links multiple switches together so they operate as a single unit, avoiding the need to upgrade to a larger switch.

This article explores everything you need to know about switch stacking, including setup, advantages, and licensing considerations.

What Is Switch Stacking?

Switch stacking links multiple physical switches together so they function as a single logical device. To the network, they appear and operate as one unified switch.

In the past, adding more ports usually meant upgrading to a larger switch or connecting another switch via a trunk port. With switch stacking, your network becomes more flexible—you can scale simply by adding switches as needed. Rather than replacing an entire core switch for a small increase in capacity, you can add a 12-, 24-, or 48-port switch (depending on the model) at a much lower cost.

Stacking also simplifies management. All switches in the stack can be controlled from a single session, reducing administrative overhead and helping prevent configuration inconsistencies.

This guide uses the Cisco Catalyst 9000 series as a reference for configuring switch stacking correctly.

Switch Stack Terminology

Here is some switch stack terminology to follow along in this guide:

• A ‘Standby Switch’ is a switch that will become the new Active Switch if the original Active Switch goes offline. In this way, a backup helps maintain the resiliency of the stack.

• A ‘Member’ is a stackable switch that operates as an additional unit within the stack.

• A ‘Stack Port’ is a port on the switch that is used to communicate with other switches in the stack. Depending on the model, a switch can have either preconfigured or user-defined stack ports.

• An ‘Active Switch’ is a switch in the stack that handles the configuration for the entire stack. All Cisco stacks have an active switch or 'Commander'. When you want to manage your stack, the Active Switch is the device that you connect to for configuration changes. The Active Switch also handles other important stack functions, such as detecting when switches enter or leave the stack, as well as upgrading outdated switches.

Right-To-Use Licensing

The software features available with Right-To-Use (RTU) licensing fall under the base or add-on license levels. The license types available are:

• Base licenses

• Network Essentials

• Network Advantage (Contains Network Essentials plus more)

• Add-on licenses

• Can be subscribed for a fixed term of 3, 5, and 7 years.

• Digital Networking Architecture (DNA) Essentials

• DNA Advantage (Contains DNA Essentials plus more)

Once the add-on license reaches the end of its initial term, you can revert to the base license by disabling the add-on and reloading the device.

Right-to-use (RTU) licensing is supported within switch stacks. A stack can include up to nine compatible switches connected via StackWise-480 ports. Within the stack, one device operates as the Active Switch, while the others function as Standby Switches. The Active Switch is the one enabled with the RTU license, and from its console, you can apply the desired license level to all standby switches simultaneously.

Cable Management for Switch Stacking

Below is an image of a Cisco StackPower Cable which is specifically intended for switch stacking. These are alternative options to using ethernet or fiber connections between the switches. The StackPower cables range from 1 to 5 feet.

Shown below is a simple full bandwidth, fully redundant cabling option for switch stacking.

A more advanced cabling option is a ring topology, creating more redundancy.

Switch Stacking Configuration

Reflect the proper prompts when you enter a configuration mode such as ‘config’, as shown in the example below. Note: the commands below are not intended for the Cisco Catalyst 9300 model. Refer to Cisco documentation for the commands for these switches. Small business switch commands will be used for stacking.

A reboot is required to apply the changes made. This is why the configuration save is important prior to rebooting.

The process can be repeated as needed with an additional switch, but be sure to edit the unit number and port numbers as they relate to each switch.

Configuring Switch Stack Priority

A priority of 15 sets the switch to the ‘Active’ role, a priority of 14 sets the switch to the ‘Standby’ role, and a priority of 13 sets the switch to the next ‘Standby’ role. Continue down the value list to set the next standby priority.

Here are examples of priority commands:

View Switch Stack Configuration Settings

The following command can be used to view the switch stack configuration settings:

PiVIT-9300-1 # show switch

This command will show you the roles, priorities, and each switch's current state. Note that even though the switches are logically joined, they are still recognized individually by MAC addresses.

FAQs

How many switches can you stack?

The maximum number of switches you can stack depends on the models/series you’re using. For instance, Netgear allows up to eight switches to be stacked, whereas with some Cisco series, you can stack up to nine switches. For more information about Cisco switches, check out our ultimate guide for enterprises.

What is the difference between trunking and stacking switches?

Both trunking and stacking involve connecting multiple switches, but their purposes are different.  Trunking involves bundling multiple physical connections between switches to increase bandwidth and create a single logical connection. It's typically used to connect switches in various parts of a network. Stacking, on the other hand, involves physically connecting multiple switches to create a single logical unit, allowing them to be managed as a single entity with shared resources and simplified configuration.