Why Stack Switches? Benefits and Step‑by‑Step Guide to Building a Stacked Network

Stacking refers to connecting multiple switches that support the stacking feature with stacking cables, logically virtualizing them into a single switch that participates in data forwarding as one device. It is a widely used horizontal virtualization technique that enhances reliability, expands port count, increases bandwidth, and simplifies network topology.

Why Stacking Is Needed?

Traditional campus networks rely on device and link redundancy for high reliability, resulting in low link utilization and high maintenance costs. Stacking virtualizes several switches into one, simplifying deployment and reducing maintenance workload.

Improved Reliability Stack members provide redundant backup; if Switch A fails, Switch B takes over, ensuring continuous operation. The stack also supports cross‑device link aggregation for additional redundancy.

Expanded Port Count When user density exceeds the port capacity of a single switch, additional switches can be added to the stack to increase the total number of ports.

Increased Bandwidth By adding switches to the stack and configuring multiple physical links as an aggregated group, the upstream bandwidth of the stack can be significantly increased.

Simplified Topology Multiple devices appear as a single logical unit, eliminating the need for complex protocols such as MSTP and simplifying configuration while still providing rapid failover through cross‑device link aggregation.

Long‑Distance Stacking Switches on different floors can be linked into a single stack, reducing each building to one access device, simplifying the network, and providing multiple uplinks for greater robustness.

Which Devices Support Stacking?

Huawei S series campus switches and CloudEngine data‑center switches have models that support stacking. For the S series, only box‑type switches support stacking; two chassis switches together form a cluster. For CloudEngine, both chassis and box models support stacking, though chassis models only allow two devices per stack.

How to Build a Stack?

Master, Standby, and Slave Switches

All switches in a stack are called member switches and assume one of three roles:

Master : Manages the entire stack; only one master exists.

Standby : Backup for the master; takes over if the master fails.

Slave : Handles traffic forwarding; multiple slaves increase stack bandwidth.

Stack ID

The Stack ID uniquely identifies each member switch within the stack and corresponds to the switch’s slot number.

Stack Priority

Each member switch has a priority value; a higher value increases the likelihood of being elected as the master.

Stack Creation Process

The stacking process consists of four phases:

Select stacking cables and connection method based on network requirements. Different products support different physical topologies:

For S series campus box switches and CloudEngine data‑center box switches, both chain and ring topologies are supported.

For CloudEngine data‑center chassis switches, SIP port or regular business port connections are supported.

Master election. After power‑on, all members elect a master that will manage the stack.

Assign Stack IDs and elect a standby switch. The master distributes topology information, assigns IDs, and selects the first‑booted non‑master as standby.

Synchronize software versions and configuration files. Members automatically download compatible software from the master if versions differ, and the master propagates its configuration to all members.

The stack can operate with different but compatible software versions; mismatched members update automatically.

Configuration files are centrally stored on the master and synchronized to all members, ensuring consistent operation even after a master failure.