Routing Between VLANs

Question 1

What are the options for inter-VLAN routing?

Answer 1

1. Router with separate interfaces in each VLAN (old way, but still works).
2. Router on a stick - using trunk ports from Switch to Router with sub-interfaces.
3. Layer 3 switch - inter-VLAN connectivity is done at wire speed due to ASICs.

Question 2

What commands are needed to configure Router on a stick

Answer 2

The screenshot shows the router configurations needed.

On a switch that’s connected to that router port, the configuration would be:

Switch(config)# interface GigabitEthernet 0/1

Switch(config-if)# switchport mode trunk

Question 3

What is a SVI?

Answer 3

Switch Virtual Interface - created for VLANs when configuring inter-VLAN routing.

Question 4

How would you configure a L3 Switch to do inter-VLAN routing?

Answer 4

1. Enable routing on the switch at the global configuration level.
2. Configure the VLAN’s SVI with an IP address in the proper subnet that matches with the VLAN.
3. Enable the VLAN’s SVI.