SW2：
en
conf t
hostname SW2
vlan 10
vlan 20
int e0/2
switchport mode access
switch access vlan 10
int e0/3
switchport mode access
switchport access vlan 20
int e0/0
switchport trunk en dot1q
switchport mode trunk
int e0/1
switchport trunk en dot1q
switchport mode trunk
SW3:
en
conf t
hostname SW3
vlan 10
vlan 20
int e0/1
switchport mode access
switchport access vlan 10
int e0/2
switchport mode access
switchport access vlan 20
int e0/0
switchport trunk en dot1q
switch mode trunk
R1:
en
conf t
hostname R1
int e0/0
no shut
int e0/0.10
en dot1q 10
ip add 192.168.1.254 255.255.255.0
int e0/0.20
en dot1q 20
ip add 192.168.2.254 255.255.255.0