Connecting two overlay meshes into a single mesh

[Ivan Vilata i Balaguer]

Hi everyone.  I'm wondering whether a setup like the one described below
would be possible with Tinc:


       nodeA1                                            nodeB3
         |                                                  |
    (Network A) --- [GWA] --- (Internet) --- [GWB] --- (Network B)
         |                                                  |
       nodeA2                                            nodeB4


nodeA1, nodeA2 and GWA (along with other hosts not depicted above) are
connected in a ig mesh Network A.  On top of it they define a private
mesh network using Tinc in a similar way as described [here][1].  Every
nodeAx in Network A connects to GWA and some nodeAx also connect between
themselves (that's why it's also a mesh).  Every nodeAx has a small
network behind it with addresses in the Tinc mesh.  Summarising, the
respective Tinc subnets are:

- nodeA1: X.Y.1.0/24
- nodeA2: X.Y.2.0/24
- GWA:    X.Y.0.0/16

The same happens in Network B with nodeBx and GWB, and they define the
same Tinc network (with subnets that don't clash with Network A's):

- nodeB3: X.Y.3.0/24
- nodeB4: X.Y.4.0/24
- GWB:    X.Y.0.0/16

I know that both separate Tinc meshes would work with a setup like the
one described in the link above (I checked!).

My doubt is: if GWA and GWB also connect to each other using Tinc via
the Internet, would traffic from nodeA2 be routed by GWA and GWB to
nodeB3 and back?  Is it ok for Tinc that both GWA and GWB define the
same subnet?  Would GWA forward traffic not addressed to nodeAx nodes to
GWB?

Thank you very much!

[1]: http://www.allsundry.com/2011/04/10/tinc-better-than-openvpn/
-- 
Ivan Vilata i Balaguer -- https://elvil.net/