Hello Bird team, Thank you for the great tool BIRD. I would like to open an issue (bird v2.0.7) about the local_pref. Today we hit an issue with one filter. if ! is_geo_region_local() then { bgp_local_pref = bgp_local_pref - 200; # If not defined, MED has a type of void instead of int if defined(bgp_med) then { bgp_med = bgp_med + 50; } else { bgp_med = 50; } } When some prefixes with the local_pref was below 200 (for example 100), the value overflow: localpref (unsigned integer 4^32) 100 - 200 = -100 = 4 ^ 32 - 100 = 4294967296 - 100 = 4294967196 We had the prefixes with this value 4294967196 X.X.X.X/32 unicast [ipv4_rr01 07:51:49.603 from 100.100.254.137] * (100/84285) [AS65030?] via 100.99.0.100 on eth1.666 Type: BGP univ BGP.origin: Incomplete BGP.as_path: 64619 65030 BGP.next_hop: y.y.y.y BGP.med: 50 BGP.local_pref: 4294967196 BGP.community: (35280,1040) (35280,2070) (35280,3110) BGP.originator_id: y.y.y.y BGP.cluster_list: 0.0.0.30 We had an exception to check the value of local_pref (on the filter) but can we have the something on the code, not to overflow the local_pref, for example SET to 0 if the value overflow? Our filter looks like this now if bgp_local_pref > 200 then bgp_local_pref = bgp_local_pref - 200; else { bgp_local_pref = 0; } Best Alexandre Corso alexandre@ac <mailto:alexandre@acorus.net>orso.fr