Hi,
I'm trying to see if bird can accomplish the following and so far I can't
seem to find a way to do it.
Quick summary:
I want to be able to modify a route (the actual IP/mask) between 2
interfaces.
Setup is as follows:
table A: routes learned as normal
table B: I want to advertise a specific route into table B if there is
another specific route learned on table A. Note that the route in table B
is different than A but I want to link/convert them somehow.
Why would I want to do this? This Linux setup is performing NETMAP to
convert IPs when forwarded between 2 interfaces. I know the exact prefixes
so I can enter them in the config but I want to dynamically advertise those
into B but only if they are reachable via A.
My first attempt was to use a proto pipe between the two tables and simply
change the net variable:
protocol pipe a_b_pipe {
table b;
peer table a;
import filter { # a -> b
if net ~ A.B.C.D/E then { net = F.G.H.I/J; accept; };
reject;
};
export none; # b -> a
}
but that doesn't work:
bird: /etc/bird/bird.conf:24:56 This static attribute is read-only.
My second attempt was to setup filters/functions on the protos in table A
to set some variable if the specific route is seen, then reference that
variable via a static proto route in table B. This seems to be a no go as
there are global constants (define xxx;) but attributes are local and
function variables are also local scope.
My third thinking was to somehow use bfd to cross the bridge as it were..
setup a static route with the bfd option in table B and have it
communicate with a bfd in table A, but there doesn't seem to be any way to
start/stop bfd on the table B side based on learning a specific route in
table B.
Other suggestions appreciated, or is this just not possible?
