R3a and R3b share area 1 and summarize. They run HSRP and R3a is active. So traffic via R3a goes to R1a over serial, then via R1b to R2b then R2a. The reverse goes from R2a then over vpn to R3b.

but I didn't want to threadjack. I have two separate subnets that need to stay in contact, but for various administrative reasons, they only communicate over IPv6 tunnels. Each of these tunnels is ...

A couple weeks ago I wrote a blog about how I can fix anything with a tunnel. In that blog I described a situation where using a campus LAN physical box design, instead of a triangle design, can lead ...