We have a series of wireless antennas deployed in mesh with the babel protocol using bird. Two of those antennas advertise the route 10.0.0.0/8. The rest of the antennas choose one of the two outputs depending on the babel protocol. How can I force it to go out through one or the other exit?
You cannot force it, but you can strongly discourage one of the two nodes. Say something like this: filter babel_discourage { if babel_metric < 1024 then babel_metric = 1024; accept "ok"; }; protocol babel { ... ipv4 { export filter babel_discourage; }; ipv6 { export filter babel_discourage; }; }; You should not do the opposite: a node can safely increase the metric it announces, thus discouraging its use by other nodes, but it should not decrease its metric artificially, since that might defeat Babel's loop avoidance. -- Juliusz