Tinc routing question

[Guus Sliepen]

On Wed, Jan 10, 2018 at 11:29:22AM +0100, cr0n wrote:

> Meta connection graph:
> 
> A – B – C – D
> │           │
> └─ E ───────┘
> 
> Node configuration:
> 
> • StrictSubnets = yes
> • AutoConnect = yes
> • B has Forwarding = internal, all other nodes have Forwarding = off
> 
> All nodes can reach each other directly with UDP *except* A and D.
> Packets from A to D and vice versa have to be forwarded.

Unfortunately, that is not going to work. The shortest path (in number
of hops) between A and D is via E. If E has Forwarding = off, then no
data will be forwarded and A and D will not be able to communicate with
each other. I am afraid this currently is a hard limitation in tinc.

> Now I'd like to transfer data from A to D. Since C and E only have small
> bandwidth, I'd like to have data from A to D being forwarded by B
> directly to D (and not via C or E). How can I get this done?

The best way is to have D ConnectTo B instead of E. This way, B will be
the best path.

> If I could somehow tell A to send packets for D always via B (and not
> via E): Would B try to directly connect to D in order to forward packets
> from A to D? Or would B forward A's packets for D to C (because of its
> meta connection to C)?

If B can make a direct UDP connection to D, then it will use that,
otherwise it will try to forward packets via C.

-- 
Met vriendelijke groet / with kind regards,
     Guus Sliepen <guus at tinc-vpn.org>
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