Packet loss when using multiple subnet#weight entries

Armin Schindler
Sun, 15 Nov 2015 13:28:02 -0000

Hello,

I have two servers (A and B) in separate locations. Both are connected
together via two tinc switches to provide two subnets on both servers.
This works pretty good. I can start my VMs on any server connected
to one of those bridges without changing any routes.
The subnets hosted on both servers (each in a bridge) are
172.16.10.0/24 (mainly on A) and 172.16.11.0/24 (mainly on B)

Now I want to connect to those servers from a third location (C) via
tinc router. The idea was to connect to both and have a failover route
if one connection fails.
So I added on A:
 Subnet = 172.16.10.0/24#10
 Subnet = 172.16.11.0/24#20
And on B:
 Subnet = 172.16.11.0/24#10
 Subnet = 172.16.10.0/24#20

Basically it seems to route all correct. But I got packet loss when
both tinc routers on A and B are running.
If I shutdown the tinc router on B, it works.

>From C I try to ping B and got about 20% packet loss. A tcpdump shows
that tinc packets are going to B and back. I can see the port 655 packet
arriving at C, but the decrypted ping-reply does not appear.

What is happening to that packet? Is the tinc on C dropping it? Do I
miss a rule or something.

Two servers run tinc 1.0.24, the other 1.0.26.

Thanks.
Armin