broadcast storm

MAC address table oscillation

Duplicate data frame

1. Elect the root switch among all switches

2. Elect a root port (RP) on the non-root switch

3. Elect a designated port (DP) in each network segment (conflict domain)

4. Block non-root and non-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

Disabled

Blocking

Listening

Learning

Forwarding

1: Port initialization or enablement

2: The port is selected as the root port or designated port

3: The port is no longer a root port or a designated port

4: forward delay timer times out

5: Port disabled or link failed

If the non-root bridge 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 and calculation of the spanning tree requires two forwarding delays (30s)

It takes 50s for a blocked port to enter the forwarding state: MaxAge 2

The aging time of the MAC address table of all interfaces that receive TC packets sent by the root bridge becomes 15s.

stp root primaer=

Set as backup root

STP

RSTP: Rapid Spanning Tree

MSTP: Multiple spanning tree (default for Huawei switches)

The highest bit: TCA

Lowest bit: TC

TCN BPDU: Topology change BPDU

Configuration BPDU: sent when calculating spanning tree

RID

RPC

BID

PID

Hello time=2s

Forward Delay=15s

Message Age=forwarded through switch 1

Max Age=20s