If we try to implement router on a stick (ROAS) for try interVLAN communication, we must to use one Phisical interfase and split it into several "logicals" interfaces. Until Now all right.
But let´s see the following diagram:
In this diagram the "correct way" to implement ROAS would be to make one Trunking Link between Switch_1 and Switch_2 and eliminate the ethernet wire in interface F0/1 on the router.
But what happen I trying to use the two interfaces of the router ?. I can´t put the same IP addresses in the subinterfaces Fastethernet0/0 and Fastethernet0/1 because I get this message:
% 192.168.0.0 overlaps with FastEthernet0/0.2
So to implement RoaS in everywhere, Is it mandatory just to use one interface of the router ?. Because I can´t see we could use more than 1 interface.