Hello Anath
When working with multilayer switches, there are two options that you can use for assigning IP addresses to Layer 3 interfaces.
In the example in the lesson, Rene could have configured Gi0/1 on both switches as a routed interface. A routed interface is a Layer 3 interface to which you can assign an IP address. Essentially, such a configuration makes that interface function the same as an interface on a router.
To configure a routed interface, use the following commands:
SW1(config)#interface gi0/1
SW3(config-if)#no switchport
SW3(config-if)#ip address 192.168.1.1 255.255.255.0
The second option is to create what is known as a Switched Virtual Interface, or an SVI. This is a virtual interface created on the specific VLAN (VLAN1 in the case of the lesson), and this is what Rene created in the lesson. All Layer 3 configurations, such as IP address and subnet mask are configured there. In that way, all hosts connected to an access port on VLAN1 on the switch have direct access to that Layer 3 interface as a default gateway. The advantage here is that multiple hosts can connect to multiple access ports on VLAN 1 and have access to that default gateway.
In the case of the routed port, you would need another physical switch to connect to that port for multiple hosts to access the default gateway.
You can find out more information about SVIs, routed ports, and related issues, take a look at the following lesson:
You may also find the following NetworkLessons notes useful:
I hope this has been helpful!
Laz