PROBLEM: I created a VLAN on my router, but I cannot see it using ‘show vlan-switch’ or Vlan Status is UP but Protocol is DOWN.
SOLUTION: Create L2 SVI.

[?] What is SVI?
https://en.wikipedia.org/wiki/Switch_virtual_interface

//Create L2 SVI over the existing L3 VLAN

Router(config-v)# vlan 10
Router(config-vlan)# exit

OUTPUT

Router# show vlan-switch


VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa1/0, Fa1/2, Fa1/3, Fa1/4                                                
10   VLAN0010                         active    Fa1/1

Copy & Paste

conf t
vlan 10
end