Hello Matt,

your preference attribute is manually set higher which takes precedence over anything specified in BGP.

If you want LLGR to work, keep both sessions at the same preference and set only bgp_local_pref which is evaluated after LLGR. Yes, these are different attributes.

Maria

On Mon, Dec 01, 2025 at 12:13:14PM -0500, Matt Corallo wrote:

It appears bird (2.17.1) doesn’t implement the required LLGR de-preferencing logic, eg in a simple test environment with LLGR and one (otherwise-preferred) session down, bird shows it as still selected even though it has the stale flag (see below). Is there any way to do the required de-preferencing with filters or would a patch to implement this be simple?

Thanks.

bird> show route for 69.59.18.0 all Table master4: 69.59.18.0/24 unicast [localsyncb 17:06:58.262 from 10.242.243.12] * (101s) [AS397444i] Type: BGP univ BGP.origin: IGP BGP.as_path: 397444 BGP.next_hop: …. BGP.local_pref: 101 BGP.community: (65535,6) unicast [localsync 2025-11-30 from 10.242.242.12] (100) [AS397444i] Type: BGP univ BGP.origin: IGP BGP.as_path: 397444 BGP.next_hop: …. BGP.local_pref: 100

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Maria Matejka (she/her) | BIRD Team Leader | CZ.NIC, z.s.p.o.