STP

STP prevents layer-2 loops in switched topologies. netverdict models root election, path cost, blocked/forwarding decisions, and common protection features in a deterministic way.

Support level

Area	Level	Notes
Classic STP	Behaviour model	Root bridge and port roles are derived from topology/config.
PVST	Behaviour model	VLAN-aware STP decisions for common Cisco-style labs.
RSTP	Behaviour model	Rapid mode configuration and deterministic role/state outcome.
MST	Partial	Instance mapping is represented where configured; full MSTP packet exchange is simplified.
BPDU guard	Behaviour model	Edge-port protection can block/error-disable ports.

Standards coverage

Standard	Coverage	Notes
IEEE 802.1D	Behaviour model	Root/path/port role concepts.
IEEE 802.1w	Partial	RSTP role/state outcome.
IEEE 802.1s	Partial	MST instance mapping surface.

Feature matrix

Feature	Status	Notes
Root bridge election	Supported	Priority then bridge ID tie-break.
Root port selection	Supported	Path cost and stable tie-breaks.
Designated/blocking ports	Supported	Prevents modelled L2 loops.
PortFast	Supported	Edge intent and guard interaction.
BPDU guard	Supported	Protects edge ports.
Root guard	Partial	Guard surface represented where implemented.
Storm control	Behaviour model	Related L2 protection in storm-bpdu module.

Vendor command matrix

Command	IOS-style	Junos-style	VyOS-style	Notes
spanning-tree vlan 10 priority 4096	Supported	n/a	Partial	Root election influence.
spanning-tree mode rapid-pvst	Supported	n/a	n/a	Mode selection.
spanning-tree portfast	Supported	n/a	Partial	Edge port intent.
spanning-tree bpduguard enable	Supported	n/a	Partial	Edge protection.
show spanning-tree	Supported	Partial	Partial	Model-derived STP state.

Behaviour notes

STP is solved to a stable topology state. The engine does not simulate every BPDU interval, but it does make the forwarding/blocking result explicit.

Examples

Canonical example

configure terminal
spanning-tree mode rapid-pvst
spanning-tree vlan 10 priority 4096
interface GigabitEthernet0/1
 spanning-tree portfast
 spanning-tree bpduguard enable
end
show spanning-tree

Vendor styles

IOS-style

spanning-tree mode rapid-pvst
spanning-tree vlan 10 priority 4096
interface GigabitEthernet0/1
 spanning-tree portfast
 spanning-tree bpduguard enable

Junos-style

set protocols rstp bridge-priority 4k
set protocols rstp interface ge-0/0/1.0 edge
set protocols rstp bpdu-block-on-edge

VyOS-style

set protocols spanning-tree mode rstp
set protocols spanning-tree priority 4096
set protocols spanning-tree interface eth1 edge

Known limits

TCN propagation timing, proposal/agreement packet races, full MST region digest behaviour, and vendor debug output are not complete support claims.