Jeremy introduces the concept of a Switch Virtual Interface in this video. This is useful on a Layer 3 (Multilayer) Switch -- a switch that can also do layer 3 work (incluing routing).
First Jeremy removes VLAN config from router R1:
Remove the sub-interfaces:
R1(config)#no interface g0/0.10
R1(config)#no interface g0/0.20
R1(config)#no interface g0/0.30
This resets the interface to its defaults:
R1(config)#default interface g0/0
View the config of R1 interfaces:
R1(config)#do show ip interface brief
Now set an IP address on R1's g0/0 interface:
R1(config)#interface g0/0
R1(config-if)#ip address 192.168.1.194 255.255.255.252
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Now Jeremy reconfigures switch 2 (SW2) as a multi-layer switch and configures it to do VLAN routing.
Reset interface g0/1 to defaults
SW2(config)#default interface g0/1
SW2(config)#ip routing <-- Enables layer 3 routing on the multilayer switch
These next two commands change int g0/1 from a layer 2 switched port to a layer 3 routed port.
SW2(config)#interface g0/1
SW2(config-if)#no switchport
Since the interface is now a routed port, it needs a layer 3 IP address:
SW2(config-if)#ip address 192.168.1.193 255.255.255.252
These next two commands tell SW2 to use R1 as its default route.
The IP address 192.168.1.194 is SW2's "next hop" and that IP address matches the one assigned to R1's connected interface up above
SW2(config-if)#exit
SW2(config)#ip route 0.0.0.0 0.0.0.0 192.168.1.194
Now view the route config on SW2:
SW2(config)#do show ip route
We can also see how an interface is configured to route with the command below. Instead of showing a VLAN ID, the VLAN column will show "routed":
SW2#show interfaces status
Now we need to configure the SVIs (switch virtual interfaces) on SW2.
Create 3 SVIs and assign an IP address to each. These IP addresses act as the "default gateways" to the PCs in the corresponding VLANs:
SW2(config)#interface vlan10 <-- This creates an SVI called "vlan10"
SW2(config-if)#ip address 192.168.1.62 255.255.255.192
SW2(config-if)#no shutdown <-- SVIs are shut down by default
SW2(config-if)#interface vlan20
SW2(config-if)#ip address 192.168.1.126 255.255.255.192
SW2(config-if)#no shutdown
SW2(config-if)#interface vlan30
SW2(config-if)#ip address 192.168.1.190 255.255.255.192
SW2(config-if)#no shutdown
Recall that access or trunk ports on SW2 were already assigned to VLANs 10, 20, and 30. So the switch has already created VLANs 10, 20, and 30.
[These are my notes from Jeremy's excellent CCNA course which can be viewed here.]
