Using location A subnet on a switch port at location B

Question

Not sure if this belongs here or under VPN. I have multiple locations that are all connected via red tunnels. Each location has its own subnet. Everything works as it is currently setup - Location A can ping / access services, etc. from location B. VLAN traffic is passed as it should be. 
 Now for the tricky part - in "Location B", I need to put one of the ports on the subnet for "Location A". In other words, I'd like to be able to plug something into a port on my switch in location B and have it think it is in Location A. 
 I thought maybe I could just add an interface on the physical interface in the remote location and tag it as a VLAN and give it a static IP address from the Location a subnet. When I do that, it does't work - in fact it basically shuts off all traffic to between location A and location B. (as soon as I disable the new interface everything returns to working as it should. 
 Any guidance would be appreciated. Thank you.

BAlfson · Answer

Here's the problem, you need to "transfer" an Ethernet connection to the other side. The way the original RED connection between the two sides is configured, that can't be done. The RED connection is like a loooong Ethernet cable, so we just make a second connection. 
 
 On the far side (let's assume it's the Client side), we assign redc1 to an Interface defined on VLAN2 and give it an IP from the subnet on VLAN2 on our (Server) side. 
 On our side, we bridge reds1 to the Interface defined as VLAN2. 
 
 Questions? 
 Cheers - Bob