Switching fabric · schematic

Spanning Tree Topology Visualization

Five switches, a dual-homed server, redundant uplinks, one loop-free tree. Drag priorities and costs to watch the root election recompute — including which cable goes dark. Fail a link to show RSTP reconvergence, trace traffic hop by hop, then flip to loop-free mode and see the same cabling carry every link forwarding.

Unofficial concept piece — not affiliated with or endorsed by HPE.

shared segment10G · c21G · c41G · c4blocked1G · c41G · c4blocked1G · c41G · c4blocked1G · c4blocked1G · c41G · c4backupCore-Acost 000:1b:3f:0a:11:01root bridgeCore-Bcost 200:1b:3f:0a:22:02Acc-1cost 400:1b:3f:0a:33:03Acc-2cost 400:1b:3f:0a:44:04Acc-3cost 400:1b:3f:0a:55:05Srv-1server · 2 NICs00:50:56:9c:77:07

RP root port · DP designated port · AP alternate (blocking) · BP backup (blocking)

Each cable label shows its speed and its path cost. Speed is the physical link rate; cost is what the election actually compares, so a faster link normally carries a lower cost and wins.

  • alternate — a blocked path to the root through a different switch. Takes over if the root port dies.
  • backup — Acc-3's second cable onto the same segment it already serves (Srv-1). Takes over only if its sibling port on that segment dies.
traffic

Acc-1 → Core-A → Acc-2 · 2 hops · cost 8

tree path 2 hops / cost 8 · loop-free path 1 hop / cost 4 — the tree takes the long way round a link you already own.

links cabled

10

links forwarding

5

blocked by STP

5

root bridge

Core-A

Modeling notes

  • One VLAN, one tree. No MSTP or per-VLAN instances, which is how most real networks claw some idle bandwidth back.
  • Five switches plus one dual-homed server stand in for a small access layer. The reconvergence bars are one representative worst case, not a measurement.
  • Path costs are small integers so the arithmetic stays readable; real costs are speed-derived.
  • Failure detection is treated as instant; in practice it depends on link-down signalling and BPDU loss.
  • RSTP's proposal/agreement handshake is shown as a single sub-second bar, glossing over edge/port-type details.
  • Loop-free mode treats the core pair as one logical device and the server cables as a single LAG; real MCLAG (MLAG, depending on vendor) / stacking hashing is more involved.
  • Traffic tracing shows one representative tree path (or two hashed paths in loop-free mode), not a full forwarding-plane simulation.