# Title Reconfiguring `import keep filtered` from off to on does not preserve already rejected routes # Description Changing a channel from `import keep filtered off` to `import keep filtered on` does not cause existing rejected routes to be reprocessed. Two histories with the same final static route, import filter, and `import keep filtered on` setting end with different filtered-route state. When the route is present before `import keep filtered` is enabled, it has already been dropped and is not re-fed after reconfiguration. When BIRD starts directly with the final configuration, the same route is retained as filtered. # Version Reproduced with: ```text BIRD 2.18+branch.master.f0f859c26cf9 ``` # How to reproduce 1. Use a single BIRD instance. No external peers are required. ```text +-------------+ | r1 | | | | BIRD static | +-------------+ ``` 2. Configure a static protocol route: ```bird protocol static static_reject { ipv4 { import filter { if net = 198.51.80.0/24 then reject; accept; }; import keep filtered off; }; route 198.51.80.0/24 unreachable; } ``` 3. Start BIRD and confirm the rejected route is not retained as filtered: ```bash birdc show protocols all static_reject ``` 4. Reconfigure only the channel option from `import keep filtered off` to `import keep filtered on`, keeping the same static route and same import filter. 5. Check the protocol counters again: ```bash birdc show protocols all static_reject birdc show route filtered protocol static_reject all ``` 6. As a control, restart BIRD directly with the final configuration (`import keep filtered on`) and the same static route/filter, then compare the same outputs. # Expected behavior Because both histories end with the same route, the same import filter, and `import keep filtered on`, BIRD should retain the rejected route as filtered in both cases. The protocol route counters should report one filtered route. # Actual behavior History A reports no retained filtered route: ```text Routes: 0 imported, 0 filtered, 0 exported, 0 preferred ``` History B reports the expected filtered route: ```text Routes: 0 imported, 1 filtered, 0 exported, 0 preferred ``` # Additional context `import keep filtered` changes how rejected routes are represented in channel state. The suspected path is `nest/proto.c:channel_reconfigure()`, which handles several channel changes but does not appear to trigger a reload/refeed for `in_keep_filtered` changes. `nest/rt-table.c:rte_update2() ` decides whether rejected routes are dropped or retained as `REF_FILTERED` based on `c->in_keep_filtered`, so changing that flag without refeeding existing routes leaves history-dependent filtered state.