Understanding Switch Stacking: Benefits, Supported Devices, and Configuration Process

Switch stacking refers to connecting multiple switches that support stacking features with stacking cables, logically virtualizing them into a single switch device that participates in data forwarding as a whole. It is a widely used horizontal virtualization technology that improves reliability, expands port count, increases bandwidth, and simplifies network deployment.

Why is stacking needed?

Traditional campus networks rely on device and link redundancy for high reliability, which leads to low link utilization and high maintenance costs. Stacking virtualizes multiple switches into one, simplifying deployment and reducing maintenance workload.

Improved reliability Member switches form redundant backups; if Switch A fails, Switch B takes over. Stacking also supports cross‑device link aggregation for additional redundancy.

Expanded port count When user density exceeds the original switch’s port capacity, additional switches can be added to the stack to increase the total number of ports.

Increased bandwidth By stacking, multiple physical uplink links from member switches can be aggregated into a single logical link, raising the overall uplink bandwidth.

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

Long‑distance stacking Switches on different floors can be stacked, making each building behave as if it has a single access device, which simplifies management and improves robustness.

Which devices can be stacked?

Huawei S‑series campus switches and CloudEngine data‑center switches both have models that support stacking. For the S‑series, only the 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 stacking of two devices.

How to establish a stack?

Master, Standby, and Slave switches

All individual switches in a stack are called member switches and can assume three roles:

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

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

Slave : Performs traffic forwarding; multiple slaves increase forwarding bandwidth. Any slave can become standby if the original standby becomes unavailable.

Stack ID

The Stack ID identifies each member switch’s slot number within the stack and must be unique.

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 stages:

Select appropriate 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 chassis switches, SIP‑port and business‑port connections are supported.

Elect the master switch. After power‑on, all members participate in master election; the elected master manages the stack.

Assign Stack IDs and elect the standby switch. The master collects topology information, distributes forwarding tables, assigns IDs, and selects the first‑started non‑master switch as standby.

Synchronize software versions and configuration files. Members automatically download compatible software from the master if versions differ, and the master’s configuration is propagated to all members to ensure unified operation.

These steps enable a seamless, resilient, and scalable stacked network architecture.