Networking · Hardware
Stacking
Also known as: Switch Stacking, Stack
Connects multiple physical switches so they operate as a single logical switch with one management interface, one configuration, and shared MAC and IP address tables.
A switch stack takes 2–8 (or more, depending on platform) physical switches and presents them to the network as one. A single IP address manages all of them. VLANs, port configurations, and firmware are managed in one place. If you add a port to VLAN 10, you do it once and it applies wherever that port lives in the stack.
The physical connection between stack members uses a dedicated stacking cable or high-speed backplane, separate from the uplink ports. Traffic between stack members transits this connection invisibly.
Stacking vs chassis
Enterprise alternatives are modular chassis switches — a single physical chassis with removable line cards. Stacking achieves similar management simplicity at lower cost using standard fixed switches. Chassis provide higher backplane bandwidth and more flexible port density, but at significantly higher cost.
Resilience
Stacked switches elect a master unit that handles management. If the master fails, another unit takes over with minimal disruption. In high-availability designs, the stack's uplinks can use LACP across multiple stack members — a link aggregation group that physically spans two switches, so a single switch failure doesn't disrupt the uplinks.