Hello! This is currently not possible. There are some thoughts how to make it possible, yet never finished and implemented. Maria On January 22, 2021 9:26:59 PM GMT+01:00, David Johnson <dave@oort.io> wrote:
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?
-- Sent from my Android device with K-9 Mail. Please excuse my brevity.