Just wanted to see if anyone could help me with an idea I wanted to try and implement. I currently have two Cisco Catalyst 6500's on our corporate network, each with their own corporate IP address. Behind each 6500, I have private networks set up that get NATted as they leave the 6500's. So, for example, I have 6500_A with IP address xxx.yyy.220.62/26 and 6500_B with IP address xxx.yyy.220.126/26. Behind 6500_A I have the private network 192.168.101.0/24 and behind6500_B I have the private network 192.168.201.0/24. I currently have a VPN tunnel set up between the external interfaces of 6500_A and 6500_B, and I am using ACL's to force traffic between the two private networks to not be NATted and to go through the tunnel. This is all working fine and dandy. What I would like to do is set up a tunnel configuration in such a way that I could have the private network 192.168.101.0/24 behind both 6500's such that it looks like one network for machines behind either 6500. Basically, I'd like to implement a VLAN-like configuration that can span layer-3. I heard this is possible using GRE tunnels, but haven't had any luck finding documentation on it.
Does anyone know if this is possible?! Thanks in advance!