Catalyst 9300 StackWise: 320, 480 and 1T Bandwidth Explained

Cisco's Catalyst 9300 naming is confusing precisely because the "StackWise" numbers describe different hardware generations, not different speeds of the same design. The official Catalyst 9300 StackWise System Architecture white paper clears it up: the number after StackWise (320, 480, 1T) is the full-ring stacking bandwidth your model can deliver when Switch Rollover Protection (SRP) is enabled. This article decodes the white paper's table so you can size a stack correctly and stop guessing what your uplinks can actually carry.

The StackWise Generations in One Table

• Catalyst 9300X (StackWise-1T) — 6 rings at 90 Gbps each = 540 Gbps full ring, doubling to 1 Tbps with SRP.
• Catalyst 9300 modular uplink models (StackWise-480) — 6 rings at 40 Gbps = 240 Gbps, doubling to 480 Gbps with SRP.
• Catalyst 9300 fixed uplink models (StackWise-320) — 4 rings at 40 Gbps = 160 Gbps, doubling to 320 Gbps with SRP.

The default back-plane stack interface speed for Catalyst 9300 and 9300X is 480 Gbps — note that default applies across the family even though the full-ring maximums differ.

What SRP Actually Does

Switch Rollover Protection makes the stack resilient to a broken or removed StackWise cable by rolling the ring over onto itself, turning a half-duplex ring into what behaves like a full-duplex path. That rollover is why the effective bandwidth doubles: 160 to 320 Gbps on fixed-uplink 9300s, 240 to 480 Gbps on modular-uplink models, and 540 Gbps to 1 Tbps on the 9300X. If an SRP-capable stack is running without SRP enabled, you are deliberately operating at half the bandwidth the hardware supports.

StackWise vs StackWise Virtual

Physical StackWise uses dedicated StackWise cables to build a single control plane across up to several switches in the same rack — the model behind the 320/480/1T numbers above. StackWise Virtual is a different technology: two switches are virtualized into one logical switch over their uplink ports, which allows the pair to be split across longer distances such as different rooms or closets. The white paper and Cisco's StackWise Virtual documentation clarify that physical stacking targets access-layer density while StackWise Virtual targets distribution and core roles where two-node pairs over uplinks make sense. Our Catalyst 9300 StackWise vs VSS vs StackWise Virtual comparison walks through the deployment choice.

Choosing the Right Model for the Stack

Match the model to the workload: fixed-uplink 9300s (StackWise-320) are fine for general access; modular-uplink models (StackWise-480) suit access blocks with heavy video or wireless backhaul; the 9300X (StackWise-1T) is for the densest access and distribution roles where the stack also carries inter-block traffic. Sizing rule of thumb: the stacking bandwidth should exceed the aggregate uplink capacity of the members, otherwise the stack backplane becomes the bottleneck during failure. For the full picture of the older Catalyst stacking options and VSS, see our StackWise vs VSS vs StackWise Virtual comparison.

原文链接：https://www.cisco.com/c/en/us/products/collateral/switches/catalyst-9300-series-switches/white-paper-c11-741468.html