[Babel-users] How to configure babeld?

[Juliusz Chroboczek]

> I find enormously few examples on the internet. Furthermore, I do not
> understand the difference between the filter in, out and redistribute.

Daniel summarised it quite well.  In my inimitable artistic style:

     in             out
   ------> babeld ------>
            | ^
            | |
    install | | redistribute
            | |
            v |
           kernel

In practice, I tend to stick to "in" and "redistribute", and leave
"install" and "out" at their default value, which is "allow".
         
> 1) Suppose I get a route from a babel neighbor and I redistribute it,
> which filters does this route go through? According to my logic `in ->
> redistribute -> out`.

"in", then "out", but the route will also be dropped if it's denied by
"install".  Don't use "install" unless you know what you're doing.

> 1) I want to send a local prefix /56 to all babel nodes. If the own /56
> prefix is received, it should be rejected.

   redistribute ip 2001:db8:dead:beef:2000::/56 le 56 allow
   in ip 2001:db8:dead:beef:2000::/56 deny

> 2) Only ULA routes with a prefix length between 44 and 64 should be
> propagated from the babel neighbors. These are to be installed also with
> one in the kernel.

  in ip fc00::/7 ge 44 le 64 allow
  in ip fc00::/7 deny

> out local ip fd5c:3e37:2666:6a00::/56 allow

Local doesn't make sense with "out", it's only for "redistribute".

> in ip fd::/8 ge 44 le 64
> in deny

That should probably read "fd00::/8".

> out ip fd::/8 ge 44 le 64
> out deny

"out" is allow by default, I suggest leaving it at its default value, and
doing all of your filtering at the "in" edge.

> redistribute ip fd::/8 ge 44 le 64
> redistribute deny

That should probably read "fd00::/8".

-- uliusz