Hello *, TL;DR: Skip to last paragraph. during the migration to Bird 2.0.0, the combined linecount of my bird config files has increased by quite a bit. The bulk of the increase is an unfortunate consequence of the bird/bird6 merge which I'll describe in the following. With Bird 1.6.3 I could reuse protocol-agnostic filter code using the following scheme: $ cat bird.conf function foo() { # some v4-specific filter checks } include "common"; $ cat bird6.conf # same thing in green $ cat common function bar() { # protocol-agnostic boilerplate with calls to foo() all over it } This approach for code deduplication has become substantially more difficult with Bird 2.0.0. I do, however, have an suggestion on how to fix this: Could you please add a way to check the current channel's AFI/SAFI from within filter code? That way, I could keep my bar() function unmodified and merge the two foo() implementations using a 'if afi = "ipv4" then { } else { }' construction. Regards, Luis Ressel