broadcast storm

mac address table oscillation

Duplicate data frame

Elect root switch among all switches Compare root bridge ID (less than)

Elect a root port (RP) on a non-root switch and compare root path cost (RPC)

Elect a designated port (DP) in each network segment (collision domain) Sender Bridge ID

Block non-root designated ports (preparatory port AP)

Root Bridge ID (RID)

Root path cost (RPC)

Sender's Bridge ID (BID)

Peer port ID (PID)

Local port ID

STP (802.1D)

RSTP (802.1W): Rapid Spanning Tree

MSTP (802.1S): Multiple spanning tree (default for Huawei switches)

Highest bit TAC

zlowest bit TC

TCN BPDU: Topology change BPDU

Configuration BPDU: sent when calculation is generated

RID: root bridge ID

RPC: root path cost

BID: Sender's bridge ID

Hello time=2s: The period for the root bridge to send BPDUs

Forward Delay=15s: Indicates the time the switch remains in the listening and learning state before sending data after the topology changes.

Message Age=forwarded through switch 1

Max Age=20s: The aging time of the current BPDU, that is, the maximum time for the port to save the BPDU.

If the non-root switch cannot receive the BPDU from the original root bridge after waiting for the Max Age time, it will recalculate the spanning tree.

The original blocked port becomes the root port to calculate the spanning tree. Requires 2 forwarding delays (30s)

It takes 50 seconds for a blocked port to enter the forwarding state. MaxAge 2*FordDelay=20 15*2=50s

The aging time of the interface MAC address of all received TC insulation messages sent by the root bridge becomes 15S.

stp enable

stp mode stp (stp mode rstp)

stp root primear or stp pri 0

stp root secondary (set as backup root)

[g0/0/1]stp cost 2000

dis stp

dis stp brief