Prevent Layer 2 loops

---

# RSTP

```
spanning-tree mode rapid-pvst
```

## Root Bridge

```
spanning-tree vlan <id> root primary/secondary
```

## Adjust costs

```
int g0/2
    spanning-tree cost 12
```

## PortFast for end clients

```
int g0/3
    spanning-tree portfast
```

## BPDU guard & Loop guard

```
int g0/3
    spanning-tree bpduguard enable
  spanning-tree guard loop
```

# MST

```
spanning-tree mode mst
spanning-tree mst configuration
    name LAB
  revision 1
  instance 1 vlan 100
  instance 2 vlan 200
  exit
spanning-tree mst configuration
    revision 2
  instance 1 vlan 300
  instance 2 vlan 400
  exit
spanning-tree mst 1 root primary
spanning-tree mst 2 root secondary

int g0/20
    spanning-tree mst 1 cost 1000
int g0/21
    spanning-tree mst 2 port-priority 64
```