I have set up a GRE tunnel between two 2811, one at the my main office and one at my chicago office. I am on a MPLS network. The only reason for the GRE tunnel is to get the ability to hold conference calls between users at both offices. Right now the Chicago office sits on a switch behind the router but the Main office is a little more complicated. I have a cisco 4507 layer 3 switch that acts as the core. So I have a connection coming in from the ISP MPLS into this switch, and then the main office router is also hooked to this switch. With everything being handeled with VLAN's on the 4507 core layer 3 switch. So I am going to attach not only the config's for the router but also the config for the switch.