I have two sites with a Cisco 3825 each. Site B is connected to the service provider with a 100 mbps link. Site A is connected with a 400 mbps link as a trunk port because it is use to receive data from other sites. Each site with its own vlan ID. For Site B the vlan ID is 10 but it was defined only in router at site A, by defining a subinterface and using encapsulation dot1q. Site B have no reference to that vlan ID but I'm assuming that the vlan 10 should be defined at the service provider's network equipment. I think that they are using MPLS but that's completly transparent for me in terms that I have no control over their MPLS configuration. For my perspective it is like having all my sites connected to a switch.
I need to configure both routers in order to extend the internal native vlan1 from site A to site B to have both sites using the same IP address scheme. In other words a server at site A is 192.168.100.1 and another server at site B is 192.168.100.2 with the same netmask. I completely clear that it is not recommendable or advisable to this over the WAN but I have to do it anyways.
I tried using GRE/Tunnels but I couldn't pull it out. I also read about L2TP and VPLS but I don't understand the concept entirely. Encryption is not a concern for me, actually I don't want to use IPSec unless there is no other option.
Can you please help me?
Thanks for your attention!