The Problem of Router-on-a-Stick Configuration on Ethernet Interface

RT1 with router-on-a-stick configuration on an Ethernet interface was unable to communicate with PC1 resides in Native VLAN due to confusion of using the main interface and subinterface.
Note: This problem does not happen on Fast Ethernet interfaces.

Below shows the configuration on RT1 which experienced the above describe problem scenario:

!
interface Ethernet0/0
 no ip address
 full-duplex
!
interface Ethernet0/0.1
 encapsulation dot1Q 1 native
 ip address 192.168.1.1 255.255.255.0
!
interface Ethernet0/0.2
 encapsulation dot1Q 2
 ip address 192.168.2.1 255.255.255.0
!
interface Ethernet0/0.3
 encapsulation dot1Q 3
 ip address 192.168.3.1 255.255.255.0
!

Below shows the root cause of the problem – RT1 unable to communicate with PC1:

RT1#debug arp
ARP packet debugging is on
RT1#
RT1#ping 192.168.1.2 rep 1

Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to 192.168.1.2, timeout is 2 seconds:
.
Success rate is 0 percent (0/1)
RT1#
RT1#sh arp
Protocol  Address          Age (min)  Hardware Addr   Type   Interface
Internet  192.168.1.1             -   cc01.01c4.0000  ARPA   Ethernet0/0.1
Internet  192.168.1.2             0   Incomplete      ARPA
RT1#
RT1#sh log | in ARP
00:07:31: IP ARP: sent req src 192.168.1.1 cc01.01c4.0000,
00:07:31: IP ARP rep filtered src 192.168.1.2 cc02.01c4.0000, dst 192.168.1.1 cc01.01c4.0000 wrong cable, interface Ethernet0/0
RT1#

Below shows the output of the show arp command after implemented a workaround – configure the native VLAN IP address on the main interface instead of the subinterface:

RT1#sh arp
Protocol  Address          Age (min)  Hardware Addr   Type   Interface
Internet  192.168.1.1             -   cc01.01c4.0000  ARPA   Ethernet0/0
Internet  192.168.1.2             0   cc02.01c4.0000  ARPA   Ethernet0/0