Here an example during studying Chapter 11 VLANs and Inter-VLAN Routing. The lab is made with Cisco Packet Tracer and contains:

• 1 Cisco 2811 router
• 3 Cisco 3560 switches
• 4 laptops
• 2 VLANs

After setting up this config, all laptops can ping each other, in both VLANs.

Below some parts of the configs of the router and the 3 switches:

Router#show running-config
!
hostname Router
!
spanning-tree mode pvst
!
interface FastEthernet0/0
ip address 172.16.10.1 255.255.255.0
duplex auto
speed auto
!
interface FastEthernet0/0.10
encapsulation dot1Q 10
ip address 192.168.10.1 255.255.255.0
!
interface FastEthernet0/0.20
encapsulation dot1Q 20
ip address 192.168.20.1 255.255.255.0
!
========================================
S1#show running-config
!
hostname S1
!
spanning-tree mode pvst
!
interface FastEthernet0/8
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface FastEthernet0/15
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface FastEthernet0/16
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface FastEthernet0/17
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface FastEthernet0/18
switchport trunk encapsulation dot1q
switchport mode trunk
!
========================================
S2#show running-config
!
hostname S2
!
spanning-tree mode pvst
!
interface FastEthernet0/1
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface FastEthernet0/2
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface FastEthernet0/3
switchport access vlan 10
!
interface FastEthernet0/4
switchport access vlan 20
!
interface FastEthernet0/5
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface FastEthernet0/6
switchport trunk encapsulation dot1q
switchport mode trunk
!
========================================
S3#show running-config
!
hostname S3
!
spanning-tree mode pvst
!
interface FastEthernet0/1
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface FastEthernet0/2
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface FastEthernet0/3
switchport access vlan 10
!
interface FastEthernet0/4
switchport access vlan 20
!
interface FastEthernet0/5
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface FastEthernet0/6
switchport trunk encapsulation dot1q
switchport mode trunk
!