Router-on-a-Stick VLAN Trunking Encapsulation and IP Address Configuration

Below shows the configuration sequence of VLAN trunking encapsulation and IP address on a router subinterface in Router-on-a-Stick setup. The VLAN trunking encapsulation must be configured prior to configuring an IP address.

RT1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
RT1(config)#int fa0/0.1
RT1(config-subif)#ip add 192.168.1.1 255.255.255.0

% Configuring IP routing on a LAN subinterface is only allowed if that
subinterface is already configured as part of an IEEE 802.10, IEEE 802.1Q,
or ISL VLAN.

RT1(config-subif)#
RT1(config-subif)#encapsulation ?
  dot1Q  IEEE 802.1Q Virtual LAN
  isl    Inter Switch Link - Virtual LAN encapsulation
  sde    IEEE 802.10 Virtual LAN - Secure Data Exchange

RT1(config-subif)#encapsulation dot1Q 1
RT1(config-subif)#ip add 192.168.1.1 255.255.255.0
RT1(config-subif)#^Z
RT1#
RT1#sh int fa0/0.1
FastEthernet0/0.1 is up, line protocol is up
  Hardware is AmdFE, address is cc01.0520.0000 (bia cc01.0520.0000)
  Internet address is 192.168.1.1/24
  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation 802.1Q Virtual LAN, Vlan ID  1.
  ARP type: ARPA, ARP Timeout 04:00:00
RT1#