Understanding Cisco StackPower
Craig McCamley
Cisco StackPower technology allows up to four (or up to eight in specific configurations) Catalyst 3750-X, 3850, or 9300 series switches to pool their power supplies into a shared resource, creating a highly reliable, "zero-footprint" redundant power system. It is designed to share power between switches, providing redundancy if a power supply fails or increasing the power budget for Power over Ethernet (PoE) devices.
Key Components & Ordering Information
- Cables: StackPower cables are thick, flexible cables with colored bands (green and yellow) to identify connections.
- 30cm Cable (CAB-SPWR-30CM=): Used for connecting switches within the same rack, generally for adjacent switches, typically costing £33–£61.
- 150cm Cable (CAB-SPWR-150CM=): Used for connections where switches are further apart, typically costing £69–£173.
- XPS 2200: The eXpandable Power System 2200 is an optional component that provides additional backup for the power stack.
StackPower Modes of Operation
- Power-Sharing Mode (Default): All available power is pooled, allowing the stack to manage power efficiently for high-density PoE needs.
- Redundant Mode: The power from the largest power supply is reserved. If another supply fails, the system uses this reserved power, ensuring continuous operation without dropping load.
Topologies and Design
- Ring Topology: The recommended setup connects the switches in a ring, offering higher reliability.
- Star Topology: In certain cases, switches can be connected in a star configuration, typically used with an XPS.
- Capacity: Up to 4 switches are typically supported in a single power stack for full redundancy, but the stack can hold more with certain configurations, though this might reduce the redundancy level.
Troubleshooting & Installation
- Cabling: Use two cables for the best reliability (ring), although one cable can work.
- Keying: StackPower cables are keyed and color-coded. A green/yellow cable connects switches to each other.
- Verification: Use show power inline and show stack-power to verify the power stack status and available power.
- Hot-Swapping: Power stack cables can generally be added or rearranged while the system is running, but it is recommended to do this during a maintenance window for safety.
Compatibility
- Catalyst 9300/9300X: Supported on all 9300 models. Note that 9300X switches currently do not support the XPS-2200.
