test(lab): rtbh pipe-table split-horizon regression gates

vxfemboy commented

2026-08-04 02:35:57 +00:00

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Adds two permanent blackwall-lab regression tests from tonight's live production RTBH-propagation debugging on AS214806: rtbh-split-horizon-pipe-blocked.kdl asserts that piping an iBGP-learned route into a separate table does NOT defeat iBGP split-horizon. rtbh-split-horizon-pipe-with-rr.kdl is the control, proving rr client (real RFC 4456 route reflection) is what actually works. See deploy repo docs/BLACKWALL.md items 5-6 for the full writeup and production verification.

vxfemboy added 1 commit

2026-08-04 02:35:58 +00:00

test(lab): rtbh pipe-table split-horizon gates -- pipe alone doesn't defeat it, rr client does

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dcf8c66a80

Regression test for a hypothesis raised while chasing the still-open "RTBH
doesn't propagate past home" bug (docs/BLACKWALL.md, deploy repo): does
importing an iBGP-learned route into a separate table and piping it into
master4 defeat BIRD's iBGP split horizon, letting it re-export to a second
iBGP peer without `rr client`?

Tested against real BIRD 2.17.1 in a 3-node netns lab (a -[iBGP]-> home
-[pipe: rtbh4 -> master4]-> exported to c over a second plain iBGP session).
Answer: no. The route's internal-origin marker survives the table copy, so
`show route export to_c` still omits it -- confirmed on the receiving side
too (`show route ... all` -> Network not found), matching the real bug.
Adding `rr client;` to the outbound session (with or without the pipe) does
let it through, with the expected RFC 4456 originator-id/cluster-list
markers -- that's the real fix, not the pipe.

Adds two permanent lab gates:
- rtbh-split-horizon-pipe-blocked.kdl: the negative result, so nobody ships
  a pipe-only "fix" that doesn't actually work.
- rtbh-split-horizon-pipe-with-rr.kdl: the control, proving rr client is
  what's actually needed.

Both wired into CI alongside the existing rtbh-bird gate.

vxfemboy force-pushed test/rtbh-split-horizon-pipe-lab from dcf8c66a80

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2026-08-04 03:40:21 +00:00

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