Router on a Stick and SVI configuration

Router on stick method and SVI (Switched Virtual Interface) are used for Inter-Vlan communication. [For detailed notes on vlan and intervlan visit this link]

Router on stick  Configuration
Configuration on switch connected to router
Switch(config)#interface fa0/10

Switch(config-if)#switchport trunk encapsulation dot1q

Switch(config-if)#switchport mode trunk

This is how we configure Switch.Interface between switch and router must be configured as trunk port.

Router(config)#interface fa0/0.10

Router(config-subif)#encapsulation dot1Q 10

Router(config-subif)#ip address 192.168.10.254 255.255.255.0
Router(config-subif)#exit

Router(config)#interface fa0/0.20

Router(config-subif)#encapsulation dot1Q 20

Router(config-subif)#ip address 192.168.20.254 255.255.255.0
Router(config-subif)#exit

Create two sub-interfaces on the router and tell it to which VLAN they belong. Don't forget to add an IP address for each VLAN.

NOTE : Don't forget to set your IP address and gateway on the computers.

SVI (Switched Virtual Interface) Configuration
Switch(config)#ip routing
Switch(config)#interface vlan 10
Switch(config-if)#no shutdown
Switch(config-if)#ip address 192.168.10.254 255.255.255.0
Switch(config)#interface vlan 20
Switch(config-if)#no shutdown
Switch(config-if)#ip address 192.168.20.254 255.255.255.0

Start by enabling routing using the "ip routing" command as we know routing is not enabled by default in switches. Next step is to create a SVI for VLAN 10 and 20 and configure IP addresses on them 

NOTE : Don't forget to set your IP address and gateway on the computers.