VLAN 2: 10.10.2.0 /24 

VLAN 3: 10.10.3.0 /24 


The physical FE port on the router will not have an IP address. The use of router-on-a-stick
requires us to use or create logical subinterfaces. While we don't have to use the VLAN numbers 
for the subinterface numbers, 
it is good to help keep  the interfaces straight. 

One subinterface must be given an IP address in VLAN 2, and the other will have an IP address in VLAN 3. 

Now, we have sub-interfaces:

After creating subinterfaces Ge 0.2 and Ge0.3 and the config looks like this: 

interface GE 0/0 

   no ip address 

interface GE 0/0.2 

   ip address 10.10.2.1 255.255.255.0 

encapsulation isl 2 

interface Ge 0/0.3 

   ip address 10.10.3.1 255.255.255.0 

encapsulation isl 3

 

Both of the above interfaces can be created under a sibgle GE0/0 physical Interface.

also, now, hosts in VLAN2 can communicate withHOSTS in VLAN3 but we need to use the IP address under 
each sub-interfcae for hosts in the respective vlans.

here, we need to use two ports on the switch in the trunking mode and connect to the router's 
subinterfaces or physical interfaces and use ISl or 802q.1 IEEE protocol for VLAN.