Cisco Catalyst 9300 StackWise vs VSS: Which Stacking Technology

When you design the access layer with Cisco Catalyst 9300 switches, the stacking question comes up immediately: do you use StackWise or VSS? The short answer is that Catalyst 9300 uses StackWise (including the newer StackWise Virtual), while VSS is a legacy virtual switching technology designed for Catalyst 6500/4500 chassis. This article explains what each technology actually is, how they compare on bandwidth, failover and management, and what that means for your 9300 deployment.

What Is StackWise?

StackWise is Cisco's physical stacking technology: multiple switches are connected with dedicated stack cables into a ring, forming a single logical switch with one management plane, one IP address and one configuration. Catalyst 9300 supports:

• StackWise-1: 80 Gbps stacking bandwidth per switch (16 Gbps per port direction × 2).
• StackWise-480: 480 Gbps per switch (on 9300X), four cables, up to 8 members.
• StackWise Virtual (SVL): virtual stacking over front-panel ports (e.g., 40/100G links) for 9300X, no dedicated stack cable.

Up to 8-9 switches form one stack. One switch is elected active (master) and runs the control plane for the whole stack; a standby takes over on failure.

What Is VSS?

VSS (Virtual Switching System) combines two physical chassis into a single logical switch. It was built for Catalyst 6500 and 4500 E-Series: two supervisors are paired over a Virtual Switch Link (VSL), one becomes active and the other standby, and the two chassis share a single control plane. VSS 144/480 refers to the VSL bandwidth (144 Gbps / 480 Gbps).

Catalyst 9300: StackWise, Not VSS

The Catalyst 9300 platform does not support VSS - it uses StackWise and StackWise Virtual. If you are coming from a 6500 VSS environment, the 9300 equivalent is StackWise Virtual on the 9300X models, which virtualizes two switches over high-speed front-panel ports without dedicated stack cables.

Comparison Table

Failover and Best Practices

In a StackWise stack the active switch handles L2/L3 protocols; when it fails the standby takes over and data plane forwarding continues on the member switches. For maximum resilience in access stacks:

• Use stackwise-virtual dual-active detection on SVL deployments to detect split-brain.
• Distribute uplinks across members - never terminate all uplinks on the active switch.
• Upgrade software with install add and ISSU where supported to avoid whole-stack reloads.

Which One Should You Use?

• Access layer with many closets → StackWise (up to 8 members, one management point).
• Two high-end access switches with 40/100G uplinks → StackWise Virtual.
• Legacy 6500/4500 core → VSS (only if you still run those platforms).

Related: Cisco Nexus vPC failover scenarios and H3C IRF stacking configuration and troubleshooting.

原文链接：https://www.cisco.com/c/en/us/support/docs/switches/catalyst-9300-series-switches/216214-understand-stackwise-480-technology-on-cata.html